Web searches for 'dry skin' reflect regional changes in weather, demographics, and housing properties

Thanks to data available from Google Trends, we are able to show the relative importance of Internet searches for the term 'dry skin' across all of the 50 states. The map below ranks the relative importance of 'dry skin' searches. For example, the state of New York is often the top ranked state for these searches because it has the highest proportion of Internet searches devoted to the search term 'dry skin'.

The key factors influencing the seasonal and geographic changes in people's interest in searching for 'dry skin' on the Internet include

  • Changes in weather

  • Age distribution of a state's population, and

  • Building properties.

Weather/Climate

In a previous blog we showed the Internet search activity for 'dry skin' across the United States for the past few years. The variations in search activity mainly represented seasonal changes in weather patterns, with the winter months exhibiting the highest searches because the levels of water vapor in outdoor air (and indoor air) are typically the lowest at this time of the year. Nevertheless, the aggregation of search activity across all states masks variations between the states. 

Age of Population

For example, as people age, their susceptibility to dry skin formation increases, and thus states with the highest proportion of residents over the age of 65 years would be expected to have higher search activity regarding 'dry skin' than states with younger populations--other factors being equal. The 5 states with the highest percentages of citizens over 65 years are

  • Florida (19%),

  • Maine (18%),

  • West Virginia (18%),

  • Vermont (17%), and

  • Pennsylvania (17%)

and the bottom 5 are

  • Alaska (9%),

  • Utah (10%),

  • Texas (11%),

  • Georgia (12%), and

  • Colorado (13%).

Even though Florida's population has the largest fraction of seniors, search activity for 'dry skin' is rarely elevated because of the state's humid climate, which reduces the magnitude of indoor drying stresses on skin. In contrast, Colorado has a very dry atmosphere, but its population is among the youngest in the US and thus the search activity for 'dry skin' is depressed.

Housing Properties

As the average age of housing in a state increases, the air exchange rate with outdoor air also tends to increase (due to air leakage across the building shell), which means that indoor humidities are more sensitive to changes in outdoor water vapor levels. The states with the largest fractions of housing built prior to 1970 are

  • New York (69%),

  • Rhode Island (63%),

  • Massachusetts (62%),

  • Pennsylvania (59%), and

  • Connecticut (58%).

The state of New York not only has old housing stock, but also has a large inventory of apartment buildings in New York City that tend to have elevated drying stresses on skin in the winter months due to low humidity levels. Pennsylvania is notable because it is in the top five category for both the age of its residents and housing. These combined factors place the residents of this state at increased risk of exhibiting dry skin and hence a greater tendency to search the Internet for this condition. 

Internet search activity for "dry skin" during the month of October, 2017. Results are normalized to the highest search popularity.

Internet search activity for "dry skin" during the month of October, 2017. Results are normalized to the highest search popularity.

Wrap Ups

  • Seasonal trends in 'dry skin' Internet searches vary across the US as function of weather conditions, age distributions among the states, and housing properties.

  • If you do a lot of business or recreational travel, be aware that where you start and end your travel will impact the drying stresses on your skin!

  • Spending the winter in Florida will result in lower drying stresses on your skin--compared to staying in the colder parts of the Midwest and Northeast.

Trends in web searches for 'dry skin' and what they mean for you

Web searches for 'dry skin' and related terms like 'dry face' and 'skin moisturizer' demonstrate distinct variations by season of the year and location. The overall search pattern for 'dry skin' in the United States for the past four years is depicted in the chart below (data from Google Trends). The seasonal trends largely represent changes in indoor drying stresses on skin that reflect increases and decreases in outdoor water vapor levels. 

Another interesting aspect of the chart is the gradual increase in search activity involving 'dry skin', which could be a function of the growing portion of the aging US population susceptible to dry skin as well as an increase in Internet search activity among members of this population cohort. 

An important observation is that as the Fall months begin, the atmosphere begins to dry out, and consequently, there is a rise in people's concern about the occurrence of dry skin. So, as Fall begins, its probably helpful to inspect those areas of your skin that are prone to dryness, as evidenced by skin roughness and skin flakes, in order to establish a baseline condition.  Then, as winter approaches with even drier outdoor/indoor air, you'll be able to respond with moisturizing lotions and creams together with a bedroom humidifier when indoor relative humidities decline below 40%.

Seasonal Trends for Internet Searches for 'Dry Skin'

Climate and Dry Skin Potential: What You Need to Know

The water vapor content of outdoor air is the key driver causing seasonal changes in the humidity levels in your residence and hence the magnitude of drying stresses on skin. In fact, because climatic patterns differ across the US, skin-care practices will also vary. The adjacent chart shows the annual average water vapor levels (also known as absolute humidity) in selected cities located in climates ranging from dry to humid. Miami stands out with its elevated water vapor level, which means of course that if you live there your skin’s higher hydration will reduce the potential for dry skin formation. In contrast, living in the Denver metro area with its low water vapor levels would mean that a much greater effort is needed to maintain skin hydration.

The annual average water vapor levels for selected US cities reflect a wide range of climatic conditions that impact your skin care.

The annual average water vapor levels for selected US cities reflect a wide range of climatic conditions that impact your skin care.

Dry Skin Meteorology

Perhaps even more interesting than differences in the annual averages in water vapor levels are the climatologic events that can increase drying stresses on skin. As an illustration, the annual average absolute humidities for Los Angeles and Atlanta are comparable, but the seasonal trends in water vapor levels are quite different. The adjacent chart for Atlanta shows distinct seasonal trends in hourly water vapor concentrations that are punctuated with multiple drying pulses (and wet periods too), particularly in the Fall months. On the other hand, the seasonal changes for Los Angeles are not as distinct, yet there are pronounced drying trends that occur intermittently that drive down the water vapor levels. You can also compare the Google Trends search results for "Dry Skin" for these cities during 2016 with the water vapor levels. 

The seasonal variations in the absolute humidities for Atlanta reveal distinct meteorologic events that produce drier outdoor atmospheres and hence drier indoor air as well. Based on hourly temperature and humidity data from US NOAA.

The seasonal variations in the absolute humidities for Atlanta reveal distinct meteorologic events that produce drier outdoor atmospheres and hence drier indoor air as well. Based on hourly temperature and humidity data from US NOAA.

The average annual water vapor level for Los Angeles is similar to Atlanta's, but the seasonal changes in water vapor exhibit a totally different pattern. Distinct drying trends occur periodically that may increase the need for skin care practices for averting dry, flaky skin.

The average annual water vapor level for Los Angeles is similar to Atlanta's, but the seasonal changes in water vapor exhibit a totally different pattern. Distinct drying trends occur periodically that may increase the need for skin care practices for averting dry, flaky skin.

The combination of high elevation and the rain shadow effect of the Rocky Mountains combine to produce one of the driest cities in the US. Residents here who are prone to dry skin may have to use both room humidifiers as well as skin moisturizers in order to increase skin hydration and minimize dry skin formation.

The combination of high elevation and the rain shadow effect of the Rocky Mountains combine to produce one of the driest cities in the US. Residents here who are prone to dry skin may have to use both room humidifiers as well as skin moisturizers in order to increase skin hydration and minimize dry skin formation.

If you’ve ever wondered why you experience drier skin during different times of the year, these charts indicate that meteorologic events (e.g., high pressure area with cold, dry air) can contribute to drier indoor air that in turn can increase the potential for dry skin formation. The magnitude of the associated drying stresses and your skin’s hydration level also depend on the properties of your residence (e.g., building materials, water vapor sources, etc.) and biochemical response(s) of your skin to dry air (which change with age). 

DSI Sense

To ensure that you are not caught off guard by drying trends or periodic meteorologic events that lead to increased drying stresses indoors, we are continuing the development of the DSI Sense sensor that measures the Dry Skin Index from indoor and temperature and humidity. Now that the beta testing is completed, we are working on the final design requirements. You can sign up to keep informed about the next steps for the sensor—we hope you’ll be surprised!

Wrap Up

  • Each climatic region of the US displays unique characteristics that will influence your skin care practices aimed at preventing the formation of dry, flaky skin. For example, a resident of Denver dealing with dry skin would want to use both moisturizers and a room humidifier because of the low levels of water vapor in air.
  • Periodic incursions of dry air into the urban atmosphere where you live will alter indoor humidities and hence drying stresses on your skin. However, since you can't sense these subtle changes, an indoor sensor that measures the Dry Skin Index would help inform your skin care practices.

Managing Your Exposure to Solar UV Radiation for Better Skin Health

With spring comes warmer weather and more opportunities to spend time outdoors exercising, recreating, gardening, etc. However, the intensity of solar radiation is also increasing, which means that precautions should be taken to reduce the likelihood of sunburns, and on the longer term, the risk of skin cancers and the photoaging of skin. Application of a sunscreen onto exposed skin surfaces is an important way of minimizing the potential for skin reddening. It should have a sun protection factor (SPF) value of 30 or higher and provide broad-spectrum protection against both ultraviolet A and B radiations. In addition, consider the use of a hat to cover your head and clothing to protect other exposed skin surfaces along with the use of sunglasses.

To enhance your skin care, though, there are additional considerations such as (1) the areas of your skin that you should focus on in reducing UV exposures and (2) whether you need to be concerned mainly about intermittent, high intensity UV exposures or long-term cumulative exposures to solar UV.

Exposure to Solar UV Radiation and the Risk of Skin Cancer

Epidemiological studies have shown that most skin cancers are concentrated on sun-exposed areas of the body, particularly the head and neck, followed by the body trunk (Narayanan et al. 2010). For example, Moan et al. (2015) reported that the relative tumor densities of squamous cell and basal cell carcinomas were much higher on the head than the body trunk for a Norwegian cohort. In contrast, they  found that the tumor densities for cutaneous melanoma were about the same on the head and torso.

These epidemiological findings suggest that the use of a hat while outdoors during periods of elevated solar UV would be an effective way of reducing UV exposures to the head and hence the risk of skin cancers. Wide-brimmed hats would provide additional protection to the neck area. Sunscreen applications to the face/neck are also beneficial for UV protection, however, Holman et al. (2015) showed that sunscreen use is fairly low for US adults--which limits its effectiveness in reducing skin cancers in the US population. Barriers to sunscreen use may be related to cost, knowledge of its benefits, inconvenience, forgetting, and a desire to tan (see Armstrong et al., 2009).

Another aspect of sun exposure that is very important to consider is that both intermittent and cumulative exposures are important risk factors in skin cancer formation! Squamous cell carcinomas are linked mainly to cumulative UV exposures, basal cell carcinomas are related to both intermittent and cumulative UV exposures, and cutaneous melanomas are primarily associated with intermittent (intense) exposures (Narayanan et al. 2010; Moan et al., 2015). 

Lifelong UV exposure-control practices should therefore be aimed at both intermittent and cumulative UV exposures in order to reduce the risks of skin cancer. Avoiding sunburns during adolescence and consciously limiting UV exposures via lifestyle choices such as wearing hats, protective clothing, applying sunscreen, etc. are all components of a healthy skin-care regimen.

Schedule Outdoor Activities to Times when the UV Index is Low

Sun-protection measures should be commensurate to the magnitude of UV solar radiation. And this means that you need to monitor UV radiation levels by time of day. For example, by limiting your time outdoors to the hours when UV radiation is low, you can dramatically cut down on exposures. Nevertheless, to ensure that UV levels are indeed low, it is imperative to monitor the expected UV Index (i.e., UVI), depicted in the next chart.

The UV Index for a given location can be simulated as a function of latitude, longitude, time of the year, surface elevation, and the level of ozone. Often the predicted values are referred to “blue sky” or “clear sky” results because the effects of cloud cover, airborne particulates, and reflected sunlight from snow, sand, etc. are not considered. Consequently, the predicted values are reasonable upper limits of the UVI for the given time and location.

The hourly UVI predicted for the location associated with the IP address of your computer or smartphone is shown in the chart below. Note the hours when the UVI is “Low” or “Moderate” in order to schedule activities outdoors for reduced exposures. If your planned outdoor activities will extend to the times when “High” to “Extreme” UVI levels are predicted to occur, then rely on sunscreen, hats, available shade, clothing, and sunglasses to control sun exposures.

Noontime UV Index Widget

Wrap Up

  • Given the elevated prevalence of skin cancers on the head and neck as well as the barriers to sunscreen use, consider wearing a hat (wide-brimmed preferred to baseball cap) as a lifestyle choice to reduce your skin cancer risk.
  • Epidemiological studies demonstrate that skin cancers are connected to both intermittent and cumulative, lifelong UV irradiation.
  • Parents should monitor their children's UV exposure to prevent sunburns, which are a risk factor for skin cancer later in life.
  • Monitoring the UV Index can help inform your daily activities and skin-care practices for avoiding UV stressors.

References

Armstrong, April W., Alice J. Watson, Maryanne Makredes, Jason E. Frangos, Alexandra B. Kimball, and Joseph C. Kvedar. 2009. “Text-Message Reminders to Improve Sunscreen Use: A Randomized, Controlled Trial Using Electronic Monitoring.” Archives of Dermatology 145: 1230–36.

Holman, Dawn M., Zahava Berkowitz, Gery P. Guy, Nikki A. Hawkins, Mona Saraiya, and Meg Watson. 2015. “Patterns of Sunscreen Use on the Face and Other Exposed Skin among US Adults.” Journal of the American Academy of Dermatology 73: 83–92.

Moan, Johan, Mantas Grigalavicius, Zivile Baturaite, Arne Dahlback, and Asta Juzeniene. 2015. “The Relationship between UV Exposure and Incidence of Skin Cancer.” Photodermatology, Photoimmunology & Photomedicine 31: 26–35.

Narayanan, Deevya L., Rao N. Saladi, and Joshua L. Fox. 2010. “Review: Ultraviolet Radiation and Skin Cancer.” International Journal of Dermatology 49: 978–86.

 

 

Monitor Indoor Air to Improve Your Dry Skin Care

Variations in the relative humidity and temperature of indoor air are directly linked to the temperature and water vapor content of outdoor air. Consequently, as the weather changes, the indoor drying stresses on skin also change—even though you can’t sense them. Adapting your skin care to the changing drying stresses requires two basic actions:

  • Monitoring the drying stresses on skin and
  • Managing the skin’s responses to those stressors.

As depicted in the accompanying diagram, a proactive approach to dry-skin prevention and care requires the monitoring of indoor humidity as well as the Dry Skin Index (DSI), which is a function of both relative humidity and temperature.

Proactive skin care to prevent and manage the potential for dry skin depends on the routine monitoring of indoor air for humidity and the Dry Skin Index. 

Proactive skin care to prevent and manage the potential for dry skin depends on the routine monitoring of indoor air for humidity and the Dry Skin Index. 

Each monitoring activity corresponds to a specific management action. In the case of humidity, it is the operation of a humidifier that releases water vapor to indoor air. For example, when relative humidity in a bedroom consistently drops below 40%, operating a room humidifier while you sleep will help reduce drying stresses and enhance skin hydration. Monitoring the DSI on a daily basis will inform your skin-care choices regarding the application of moisturizing lotions and creams to areas of your body that are prone to dryness or flaky skin.

The DSI Sense, which is now under development, is the only sensor device that will measure both indoor humidity and the Dry Skin Index to inform your skin care practices. Check out our product page for more information and then sign up to be notified about its status.

Track the Dry Skin Index for Better Skin Care during the Winter

If you experience dry, flaky skin—especially during the colder months of the year—then it will probably be beneficial for you to monitor changes in the Dry Skin Index (DSI). As I explain in another blog entry, this proprietary index measures the external drying stresses on skin caused by indoor humidity and temperature. Both of these parameters of indoor air change on a seasonal basis as a function of the levels of water vapor in outdoor air, building properties, severity of the heating season, etc.

Responding to Seasonal Changes in the Dry Skin Index

The chart below shows the monthly average DSI values calculated for a sample of houses in the northeastern US (based on data from Arena et al., 2010). The drying stresses on skin increase by almost a factor of 2 from the low value in July to the high in January. These seasonal changes in the DSI values directly coincide with the frequency of Internet searches for information regarding “dry skin” as well as “winter dry skin”. Unfortunately, because you really can’t sense the magnitude of these drying stresses on skin, it’s difficult to adapt skin-care practices in a timely manner to compensate for the external stressors. Consequently, skin-care practices are often “after-the-fact”, that is, you only consider the use of a moisturizing lotion or cream until after flaky, dry or itchy skin develops.

Average monthly values of the Dry Skin Index for a sample of houses in the northeastern US.

Average monthly values of the Dry Skin Index for a sample of houses in the northeastern US.

October marks the transition from the warm, humid summer months to the start of the heating season accompanied by cooler, drier outdoor air. If you are susceptible to dry skin during the fall and winter months, this is a good time to stock up on moisturizing lotions and creams when sales occur at your favorite skin-care shopping place.

Adjusting Dry Skin Care for Winter Cold Spells

The occurrence of “cold spells” during the winter will produce elevated drying stresses on skin. For example, the cold, dry air associated with an arctic air mass will drive indoor humidities lower, resulting in DSI levels that are higher than the monthly average values depicted in the chart above. If you’re not able to monitor the increased drying stresses on your skin that occur during such cold spells, you won’t be able to adjust your skin-care practices in a timely manner to maintain proper hydration of the stratum corneum—or the outer most layer of skin.

Buildings, Climate, and the Dry Skin Index

Residential populations living in buildings that do not easily retain moisture and/or have high air exchange rates with outdoor air will be exposed to elevated drying stresses on skin and thus have an increased risk of having cosmetic (i.e., flaky) dry skin conditions. The next chart depicts the DSI levels calculated for a sample of apartments in New York City (NYC) monitored by Quinn and Shaman (2017). Note that the levels are considerably higher than the values associated with the detached residences shown in the prior chart even though the residences are in essentially the same climatic zone! The average wintertime DSI for the detached residences is 6.6, compared with 8.1 for the NYC apartments.

Monthly average values of the Dry Skin Index for a sample of apartment buildings in New York City.

At such elevated drying stresses, the likelihood of flaky dry skin increases dramatically. In this situation, the use of a room humidifier becomes an important tool for reducing the DSI by increasing indoor humidity. Nevertheless, Quinn and Shaman (2017) found that ownership of a humidifier among the apartment residents was not associated with a significant increase in humidity. Perhaps if those residents had been able to monitor the drying stresses in their apartments, humidifier use would have increased to improve skin hydration.

Wrap Up

  • Millions of people live in cold climates where wintertime dry skin is a challenge to deal with.
  • Drying stresses on skin in indoor environments can vary considerably—even in the same climatic zone.
  • Monitoring drying stresses on skin can inform skin-care decisions ranging from the application of over-the-counter moisturizing lotions to the operation of humidifiers for nighttime hydration of skin.

References

Arena, Lois and Mantha, Pallavi and Karagiozis, Achilles N., Monitoring of Internal Moisture Loads in Residential Buildings (December 1, 2010). Available at SSRN: https://ssrn.com/abstract=1761413.

Quinn, Ashlinn, and Jeffrey Shaman. 2017. “Indoor Temperature and Humidity in New York City Apartments during Winter.” Science of The Total Environment 583: 29–35.

 

DSI Sense Prototype is Ready for Beta Testing

We now have a functional prototype of the DSI Sense that is ready for beta-testing! This version of the sensor has updated software that is optimized for low-power consumption. The coin-cell battery should now last for more than a year, assuming daily checking of the sensor results—which is a lot more convenient than wearable devices that need constant recharging.

How the DSI Sense is used

A typical use case is to place the DSI Sense adjacent to your skin moisturizers so that you can check on the level of external drying stresses on your skin, as measured by the Dry Skin Index (DSI). This index is a function of the indoor humidity and temperature in the room where your sensor is placed. The DSI will change during the course of the year in response to the levels of water vapor in outdoor air. Now, for the first time, you can adjust your skin-care practices in response to external stressors monitored by the DSI Sense.

Features

The DSI Sense uses a high-accuracy humidity and temperature sensor that makes measurements every ten minutes and computes a 24-hour rolling average of the DSI. Thus when you press the “sense” button once, you get the current DSI value as well as the one-day average. Press the button twice in a row and you’ll get the current relative humidity (in %) and temperature. You can use the relative humidity measurement to decide when to use a room humidifier.

Next Steps in DSI Sense Development

As we get feedback from our beta testers, we will make necessary adjustments in the DSI-Sense, including a new form factor that improves how it looks and operates.

Warning: Winter Dry Skin Can Lead to Itchy Skin (Winter Itch)

Cold, dry air during the winter months is the principal source of low indoor humidities that exert drying stresses on skin, which in turn increase the likelihood of dry skin— often referred to as “Winter Dry Skin”.  Dry skin may be an aggravation to deal with, but when it also results in itchy skin, or “Winter Itch” as its called, the motivation for seeking relief grows dramatically.

Dry skin (i.e., xerosis) is recognized as a leading cause of itchy skin (i.e., pruritis) among the elderly (Garibyan et al., 2013), although there are also a variety of other causes, ranging from medications to comorbidities involving kidney and liver function (Cohen et al. 2012). Consequently, as wintertime drying stresses increase, the incidence of dry skin among seniors is expected to rise as well, along with complaints of itchy skin.

Dry Skin and Itchy Skin

Long and Marks (1992) reported that the severity of itchy skin in a sample of elderly patients was directly correlated to the degree of observed skin dryness. To further examine the relationship between dry skin and pruritus, I used Google Trends to examine search trends for the terms "winter dry skin" and "winter itch" in the United States. As the graph below shows, both search terms track each other over a five-year period and their linear correlation coefficient is 0.94, where 1 equals perfect correlation or tracking. 

Winter Itch Relief

Based on the link between skin dryness and itchiness, it is reasonable to assume that increasing skin hydration (e.g., via application of a moisturizer) will reduce both skin dryness and itchy skin. Indeed, Cristaudo et al. (2015) found that the topical application of a moisturizing cream to fifty elderly patients with varying degrees of xerosis for 28 days substantially reduced their dry skin as well as itching.  But even though this particular dry-skin treatment approach for itchy skin was successful, it is important to seek personalized care from a dermatologist regarding treatment of pruritus because there are other causes for this condition.

Key Points

  • Winter dry skin and winter itch track each other as indoor drying stresses on skin change during the winter months.
  • The primary population at risk for "winter itch" consists of senior citizens due to their increased susceptibility to skin drying stressors caused by changes in skin composition with age.
  • Maintaining healthy skin hydration is an essential goal in reducing the occurrence of dry skin as well as related skin itchiness.

References

Cristaudo, A, Francesconi L, Ambrifi M, Frasca M, Cavallotti C, and Sperduti E. 2015. “Efficacy of an Emollient Dermoprotective Cream in the Treatment of Elderly Skin Affected by Xerosis.” Giornale Italiano Di Dermatologia E Venereologia : Organo Ufficiale, Societa Italiana Di Dermatologia E Sifilografia 150: 297–302.

Cohen, Kenneth R., Jerry Frank, Rebecca L. Salbu, and Igor Israel. 2012. “Pruritus in the Elderly.” Pharmacy and Therapeutics 37: 227–39.

Garibyan, Lilit, Albert S. Chiou, and Sarina B. Elmariah. 2013. “Advanced Aging Skin and Itch: Addressing an Unmet Need.” Dermatologic Therapy 26: 92–103.

Long, C. C., and R. Marks. 1992. “Stratum Corneum Changes in Patients with Senile Pruritus.” Journal of the American Academy of Dermatology 27 (4): 560–64.

 

Dry Skin Alert for Residents of the Midwest

A blast of cold, dry air is hitting the Midwest in early December, 2016, which means that indoor humidity levels will also fall as the dry air enters residences with the normal air exchange that occurs between indoor and outdoor air. Drying stresses on skin will definitely increase during the cold spell, moderated only by the building properties and indoor temperatures associated with individual houses. This is the time to be proactive about your skin care in order to control the occurrence of dry, flaky skin.

Key Tips for dealing with Winter Dry Skin

Here are the basic tips to keep your skin hydrated so that it looks and feels great during periods in the winter months when external drying stressors are elevated:

 

Your skin is aging--now what?

Biochemical changes occurring in the outer layer of your skin (i.e., the stratum corneum, or SC) as you grow older degrade the skin’s barrier function as well as its ability to retain water. Consequently, you’re more apt to experience dry skin in response to decreases in relative humidity and temperature—especially during the winter months (winter dry skin). In fact, studies have shown that a significant fraction of older adults have to deal with dry skin (or even itchy dry skin).

Background

So, what are these biochemical changes that increase the risk of dry skin with age? First of all, there is a gradual reduction in skin lipids (fats) that serve as the “cement” in the spaces between the corneocytes, or the flattened, nonviable skin cells in the stratum corneum that serve as the “bricks” in the skin barrier. Lipids inhibit the transport of water from deeper skin layers to the skin surface, and hence a reduction in lipids can adversely impact skin water losses. The primary lipids in the SC are ceramides, cholesterol, and free fatty acids. Second, the corneocytes contain a mixture of water-soluble compounds referred to as the Natural Moisturizing Factor (NMF), which are very effective in binding water and are critical to the hydration of the stratum corneum. Major components of NMF include free amino acids, pyrrolidone carboxylic acid (PCA), lactates, and urea.

In healthy, hydrated skin, enzymes are able to break down the corneodesmosomes that serve as “rivets” holding the corneocytes in place. As these rivets or connectors are degraded, the corneocytes are continually lost or shed from the skin surface (a process called desquamation). Normally the skin cells that are shed from the skin’s surface are not really visible. However, when the enzymatic processes are impaired by low water content or reduced NMF levels, the corneocytes tend to clump together and become visible as flakes or what is termed “cosmetic” dry skin.

Moisturizers for dry skin that contain natural lipids and NMF

The increased risk of dry skin as you get older is attributable in part to decreases in the lipid and the Natural Moisturizing Factor content of the stratum corneum. Not surprisingly, there are over-the-counter lotions and creams that are specifically formulated to contain one or more of the organic compounds in these natural moisturizing mixtures. 

CeraVe has both a moisturizing cream and lotion that incorporate ceramide lipids for enhancing the skin’s barrier function as well as occlusive agents that reduce water loss and humectants that help hydrate skin.  

Amlactin contains lactic acid for absorbing and retaining moisture plus enhancing the exfoliation or shedding of skin cells.

Skin Saver Tips

  • Dry indoor air caused by low water vapor levels in outdoor air increases the risk of dry skin as you get older. Use the Skin Saver Alert Tool to check if the levels merit remedial measures such as moisturizing lotions and a room humidifier.

  • Use lotions and creams that contain ceramides, urea, and/or lactate that can compensate for losses in skin lipids and natural moisturizers as you age.

  • Whatever skin-care product(s) you end up using, be sure to use them on a regular basis, as this has been shown to be a crucial aspect of their effectiveness.

References

Harding, C. R., A. Watkinson, A. V. Rawlings, and I. R. Scott. 2000. “Dry Skin, Moisturization and Corneodesmolysis.” International Journal of Cosmetic Science 22: 21–52.

Lodén, Marie. 2012. “Effect of Moisturizers on Epidermal Barrier Function.” Clinics in Dermatology, Epidermal Barrier Function: Clinical Implications and Therapeutic Relevance, 30: 286–96.

 

Hardware testing of the new DSI Sensor starts!

Work continues on the development of a sensor for monitoring the Dry Skin Index (DSI). A previous blog described the initial design work on the sensor and now I’m happy to report that we have actually received 30 prototype printed circuit boards for testing. Don Wyman of Electronic Design Solutions designed the board’s circuitry, and he is now implementing the software that runs the sensor. Once the sensor units are operational, we’ll have beta testers use them in order to get feedback that will help us improve them.

In other news, I worked with Lexi Steele of Hearthfire Creative to come up with a name for the new sensor as well as an appropriate logo design. Based on that effort, we are announcing with this blog the official launch of the DSI SENSE (see photo below).  Its primary purpose will be to help people easily monitor the drying stresses on skin due to changes in indoor humidity and temperature so that they can proactively implement the appropriate skin care solutions.

Testing has begun with the first printed circuit board for the DSI sensor prototype.

Testing has begun with the first printed circuit board for the DSI sensor prototype.

Let October Be Your Skin Care Preparedness Month!

The month of October for most of the United States marks the transition between the warm, humid, part of the year and the cooler months that coincide with higher indoor drying stresses on skin due to lower indoor humidities and temperatures. As the map below shows, in early October, 2016, much of the western US had outdoor water vapor levels below 10 g/m3, while the levels in the Midwest and East were gradually trending toward that level.

Regional climatic conditions across the USA drive changes in outdoor water vapor levels, which in turn directly impact indoor humidities and associated drying stresses on skin.

Regional climatic conditions across the USA drive changes in outdoor water vapor levels, which in turn directly impact indoor humidities and associated drying stresses on skin.

During the next several months indoor drying stresses on skin will increase even more due to reduced humidities and temperatures as the heating season begins in earnest. So, in anticipation of those greater environmental stressors, it’s a good time to prepare for the associated skin-care requirements.  

Shop for Moisturizing Lotions and Creams

If your skin moisturizer needs replacement (time to check?), consider shopping for good deals now so that you avoid the higher costs of last minute shopping.  For your convenience, we have links to popular moisturizers at Amazon. Regardless of the moisturizer you select, remember that it’s the regular use of a moisturizer rather than its ingredients that is the real secret to dry skin care.

Check Out Room Humidifiers

If you have never used a room humidifier to deal with the low indoor humidities associated with the winter months, consider evaluating different brands that may suit your needs. One strategy is to use a humidifier in your bedroom while you sleep, which will help hydrate your skin as well as your nasal passages.

Skin cancers, UV sunlight exposures, and Proactive Skin Care

Two key challenges in year-round skin care involve (1) dealing with dry skin caused by changes in indoor humidity and temperature (i.e., external drying stressors) and (2) managing exposures to ultraviolet (UV) radiation from the sun to reduce the risk of skin cancer as well as photoaged skin. The benefits of improved skin hydration derived from the application of moisturizing lotions and/or the operation of room humidifiers can be observed within days. In contrast, control of UV exposures includes both short-term benefits (i.e., prevention of sunburned skin) and long-term benefits (i.e., reduced skin cancer risk).

But while the motivation to avoid sunburns can be quite high, depending in part on your susceptibility to skin reddening, the motivation to prevent skin cancer years into the future may not be as strong because the benefits are uncertain. But the good news is that skin cancer prevention can be incorporated into your daily skin care practices so that you enjoy both the immediate benefits of healthy skin now as well as a reduced risk of skin cancer in the future.

Before I outline the features of an integrated skin care strategy, let’s review some background information on skin cancer.

Types of Skin Cancers

  • Basal cell carcinoma (BCC) originates in the basal cells of the epidermis, primarily in areas that are exposed to sun such as the head and neck. Although it is the most common type of skin cancer, it doesn’t usually metastasize or spread to other organs and is rarely fatal if properly treated.
  • Squamous cell carcinoma (SCC) is a skin cancer that starts in squamous cells or the flattened cells present in the outer layer of skin. This cancer is less common than BCC, but it can be more invasive if untreated and in some cases can be fatal. Skin lesions from SCC are normally found on sun-exposed areas of the body. Basal and squamous cell carcinomas are often referred to as Nonmelanoma Skin Cancers (NMSC), and they typically occur in people older than 50 years. In 2006 there were over 2 million medical treatments for these NMSCs among the US Medicare population (Rogers et al. 2010).
  • Cutaneous melanoma (CM) is the rarest of the three primary types of skin cancer, but it is the most dangerous if untreated. This cancer forms in melanocytes located in the basal layer of the epidermis.  Unlike BCC and SCC, which are concentrated on the head and neck, cutaneous melanoma is capable of developing anywhere on the body, such as on the trunk of the body and legs.

UV radiation and skin cancer

Ultraviolet radiation (UVR) reaching the earth’s surface from the sun consists of UVA (wavelengths of 315 to 400 nm) and UVB (280-315 nm) electromagnetic radiations. Ultraviolet B radiation is more energetic that UVA, but UVA penetrates deeper into the skin. Both UVA and UVB radiation have been shown to damage dermal DNA (although by different mechanisms) and can also impact the skin’s immune system (Narayanan, Saladi, and Fox 2010). Cumulative exposure to solar UVB radiation is the primary determinant of SCC, whereas BCC is a function of both cumulative and intermittent UVR exposures (e.g., sunburns)—particularly during childhood.  Cutaneous melanoma is related mainly to intermittent UVR exposures, but the relative roles of UVA and UVB are still debated (Moan et al. 2015).

Ultraviolet radiation (UVR) from the sun is grouped into two categories based on wavelength: UVA (315 to 400 nm) and UVB (280-315 nm). The biological effects of each UVR are not identical because the mechanisms of how they interact with skin tissue differ.

Ultraviolet radiation (UVR) from the sun is grouped into two categories based on wavelength: UVA (315 to 400 nm) and UVB (280-315 nm). The biological effects of each UVR are not identical because the mechanisms of how they interact with skin tissue differ.

                    

Susceptibility (Modifying Factors) to Skin Cancer

Skin pigmentation is perhaps the most important physiological factor that controls skin cancer. The melanin pigment absorbs UV radiation irradiating skin and thus serves as a natural photoprotective agent (Brenner and Hearing 2008). Epidemiological studies have consistently shown that people with light skin have a greater risk of skin cancer than those with dark skin, which is consistent with the photoprotective properties of melanin.

Skin Cancer Prevention

Research conducted in Australia has demonstrated that regular sunscreen use reduces the risk of SCC and CM, but not BCC (Iannacone, Hughes, and Green 2014).  Failure to observe a protective effect for BCC may be due to the mechanism(s) by which basal cell carcinomas are induced. For example, if UV exposures during adolescence are an important determinant of BCC risk, then UV protection later in life may be less effective, even though BCC is related to cumulative UV exposures. Nevertheless, since BCC, SCC, and CM risks are moderated by UVR exposure, on-going UVR protection is important for the maintenance of healthy skin.

Integrated Skin Care Strategy for Addressing Dry Skin and Skin Cancer Risks

The approaches for managing the risks of dry skin and skin cancers are similar because they both rely on three concepts: LEARN, MONITOR, and MANAGE. For example, as we improve our understanding of the relationships between external skin stressors together with other risk factors and skin endpoints of concern, we are better able to devise successful strategies for mitigating effects. In this regard, an essential activity is to routinely MONITOR the external stressors that impact skin and then to implement the appropriate remedial measures (i.e., MANAGE).  The two relevant measures of external skin stressors are the Dry Skin Index (DSI) and the Ultraviolet Index (UVI). The DSI represents the drying stress of indoor relative humidity and temperature on skin, whereas the UVI is a measure of the biologically-weighted exposure to UVA and UVB radiation from the sun.

Both indexes follow distinct seasonal trends, with the UVI following sunlight intensity and the DSI changes in outdoor water vapor levels. By routinely tracking these indexes and then adapting skin care responses appropriately, you will have established a lifestyle that helps ensure year-round healthy skin and decreases the risks of skin cancer as you age. Your skin-care tools will consist of (1) moisturizing lotions/creams and a room humidifier to enhance skin hydration for dealing with dry skin and (2) broad-spectrum sunscreens, protective clothing, hats, and sunglasses to reduce UVR exposures for reducing risk of skin cancer. In addition to these skin care practices, you’ll have to incorporate lifestyle changes that mean limiting time in the sun during the peak hours of 10 am to 4 pm. If you are a parent, then an added benefit of your routine skin care practices should be an increased awareness of the need for sun protection for children under your care.

Summary

  • Exposure to ultraviolet radiation from the sun is a leading cause of skin cancers, including basal cell carcinoma, squamous cell carcinoma, and cutaneous melanoma—particularly in people with light colored skin.
  • Managing the risks of skin cancers and dry skin caused by environmental skin stressors involves the same core practices, namely, monitoring the stressors and then adopting the appropriate skin-care responses.
  • Routine monitoring of the Dry Skin Index and the Ultraviolet Index represents a core practice for maintaining healthy skin throughout the year!

References

Brenner, Michaela, and Vincent J. Hearing. 2008. “The Protective Role of Melanin Against UV Damage in Human Skin.” Photochemistry and Photobiology 84: 539–49. doi:10.1111/j.1751-1097.2007.00226.x.

Iannacone, Michelle R., Maria Celia B. Hughes, and Adèle C. Green. 2014. “Effects of Sunscreen on Skin Cancer and Photoaging.” Photodermatology, Photoimmunology & Photomedicine 30: 55–61. doi:10.1111/phpp.12109.

Moan, Johan, Mantas Grigalavicius, Zivile Baturaite, Arne Dahlback, and Asta Juzeniene. 2015. “The Relationship between UV Exposure and Incidence of Skin Cancer.” Photodermatology, Photoimmunology & Photomedicine 31: 26–35. doi:10.1111/phpp.12139.

Narayanan, Deevya L., Rao N. Saladi, and Joshua L. Fox. 2010. “Review: Ultraviolet Radiation and Skin Cancer.” International Journal of Dermatology 49: 978–86. doi:10.1111/j.1365-4632.2010.04474.x.

Rogers HW, Weinstock MA, Harris AR, and et al. 2010. “Incidence Estimate of Nonmelanoma Skin Cancer in the United States, 2006.” Archives of Dermatology 146: 283–87. doi:10.1001/archdermatol.2010.19.

The Water Vapor Content of Outdoor Air Really Matters to Your Skin!

We know that water vapor in outdoor air continually enters a residence and changes the level of indoor relative humidity.

Consequently, there should be a direct connection between local weather conditions, for example how dry or humid the air is, and people’s tendency to have dry skin caused by exposures to indoor humidity and temperature stressors. Moreover, it’s probably safe to assume that as dry skin forms due to such drying stresses, people will be more inclined to conduct Internet searches to learn about their dry skin and how to treat it. To examine the relationship between outdoor water vapor levels and Internet searches referring to dry skin (as a proxy for actual dry skin formation), I collected concurrent data on “dry skin” web searches (from Google Trends) and ambient water vapor levels for two major cities that reflect different demographics, building properties, and climates:  Chicago, USA, and Tokyo, Japan.

“Dry Skin” Internet Searches versus Water Vapor Levels in Outdoor Air

Let’s begin by looking at the relevant data for Tokyo, as shown on the adjacent chart. The y-axis represents the frequency of web searches for the term “dry skin” (translated to Kanji characters). Search results are normalized so that the highest response rate is assigned a value of 100. The x-axis shows the monthly values of absolute humidity (i.e., the concentration of water vapor in air, expressed in g/m3). One interesting feature of the plot is the divergent responses that occur at an absolute humidity of around 5 g/m3. To simulate this response pattern, I created a statistical model that categorized water vapor data into either [1] a special cold season, defined by the months of November through January, or [2] all other months of the year. The resulting two-season model predicts “dry skin” searches (depicted by green squares) from absolute humidity and captures the Internet search responses occurring at low absolute humidities.

Predicted and observed changes in Internet searches for “dry skin” among residents of Tokyo, Japan .

Predicted and observed changes in Internet searches for “dry skin” among residents of Tokyo, Japan.

I used the same analytical approach with the Chicago data and the results for the observed and predicted search term activity for “dry skin” also showed that a two-season model can be used to represent Internet search patterns for “dry skin”.

Predicted and observed changes in Internet searches for “dry skin” among residents of Chicago, USA.

Predicted and observed changes in Internet searches for “dry skin” among residents of Chicago, USA.

What the results mean

The elevated web search results during the “cold season” correspond to the heating seasons in both Chicago and Tokyo, which means that indoor temperatures are reduced compared to the rest of the year. In addition, the absolute humidities of outdoor air during the winter months are typically the lowest of the year in temperate climates because the colder air holds less water vapor. Cooler indoor temperatures along with lower humidities in turn produce higher values of the Dry Skin Index since it increases as relative humidity and temperature decrease. Therefore, we would indeed expect elevated Internet search activity regarding “dry skin” as a result of the higher drying stresses during those months.

Internet search activity for the term “dry skin” among the residents of both cities gradually diminishes as outdoor water vapor levels rise—even to levels as high as 20 g/m3. This suggests that dry skin care for these populations extends year round, but is less urgent during the summer months when humidities are highest.

Despite the similarities between the Chicago and Tokyo data, the unique combinations of climate, building properties, and demographics for these cities make it difficult to generalize to other locations. For example, wood-frame residences absorb/desorb water vapor differently than buildings of masonry construction and older residential populations are more susceptible to drying stressors on skin. Consequently, variations in these and other parameters will directly influence the nature and magnitude of drying stressors on skin. The best solution to the challenge of monitoring drying stresses unique to your location is to track the Dry Skin Index with a sensor that can be placed in your home or carried with you in a purse/backpack or simply placed next to your moisturizing lotions.

Wrap Up

  • Internet search activity on Google Trends for the term “dry skin” among residents of Chicago and Tokyo vary in response to changes in outdoor water vapor levels

  • The cold season months of November through January produce the highest search activity due in part to low indoor humidities and temperatures that exert higher drying stresses on skin.

  • Dry skin care in both cities is essentially a year-round activity, but is less important during the warmer, more humid months of the year.

Design work begins on a device to help people monitor humidity and temperature stressors causing dry skin

We are happy to announce that work has begun on a sensor device that is specifically designed to track the drying stresses on skin caused by changes in relative humidity and temperature. As you probably know, you really can’t sense these drying stresses, and so it’s hard to optimize your skin care to avoid dry, flaky, and even itchy skin.

The new device employs a high accuracy humidity and temperature sensor to compute the Dry Skin Index (DSI), which we developed as an easy-to-use measure of drying stresses. Although a lot remains to be done, our initial design is based on a small form factor (powered by a coin-size battery and uses an LED display) so that it can easily be put in a purse or backpack or placed next to your moisturizing lotions at home.

The easy to view LED screen quickly gives you the current DSI as well as the trailing 3-day average value. No more dry-skin surprises that are caused by exposure to dry indoor air!

The new sensor device for monitoring drying stresses on skin includes a high accuracy humidity and temperature sensor, coin cell battery, microprocessor, LED display, and tactile switch in a compact design. 

The new sensor device for monitoring drying stresses on skin includes a high accuracy humidity and temperature sensor, coin cell battery, microprocessor, LED display, and tactile switch in a compact design. 

If you would like periodic updates on this break-through product, please sign up here!

The Secret Behind the Effective Use of Skin Moisturizers

Does this situation sound familiar...

You observe some flaky dry skin on your face, arms or legs and so then you decide to buy a moisturizing lotion or cream. But unless you already know what product you are going to purchase, it’s somewhat daunting to select a moisturizer because of the multiple brands available as well as the wide variety of different formulations and ingredients. Moreover, there can be significant differences in prices. Which moisturizer will be most effective for you? Is it important to buy a specific type of face lotion? How do you evaluate the various claims on the products? Should you choose an organic body lotion or perhaps a natural face moisturizer? What's all the buzz with coconut oil for skin?

There are bewildering arrays of ingredients in moisturizing lotions and creams, but take courage; dry skin care doesn’t fully depend on your choice of moisturizer!

There are bewildering arrays of ingredients in moisturizing lotions and creams, but take courage; dry skin care doesn’t fully depend on your choice of moisturizer!

But what if there is another factor, other than the moisturizing formulation or brand, that is actually more important in alleviating dry skin caused by exposure to indoor drying stresses? Well, the answer may come as surprise, but a recent study by Shim et al. (2016) of 80 people found that is was the consistent use of a moisturizer over a period of 4 weeks rather than its formulation that was the key is restoring the barrier function of dry skin.

The study participants (20 to 70 years of age) were randomly assigned to one of 5 treatment groups, and they each applied a preselected moisturizer (one of six formulations) to their left shin and a different one to their right shin. Baseline observations included clinical evaluations of skin dryness and instrumental measurements of skin hydration and the transepidermal water loss rate. At the end of the study period, there were no statistically significant differences in either clinical or instrumental measures between the moisturizers! The only commonality was the regular daily use of the lotions by the study participants over the course of 4 weeks.

These results are not an outlier, as other studies have also demonstrated the value of regular use of moisturizers for restoring impaired barrier function of skin (e.g., Carville et al. 2014; Kucharekova et al. 2003). So, the “secret” for maintaining healthy skin depends largely on your personal care practices, not on your skill in selecting the “best” moisturizer!

Take homes

  • The regular use of a moisturizing lotion or cream is undoubtedly the most important factor in restoring the barrier function of the stratum corneum and thus controlling dry skin caused by external drying stressors.
  • If you’re in a rush to deal with dry skin, then simply purchase any popular moisturizer (lotion or cream) and then moisturize regularly.
  • You may ultimately prefer one particular moisturizing brand after personal use and evaluation, however, the consistent application of that product to impacted skin will largely determine how effectively it supports your dry skin care.

References

Carville, Keryln, Gavin Leslie, Rebecca Osseiran-Moisson, Nelly Newall, and Gill Lewin. “The Effectiveness of a Twice-Daily Skin-Moisturising Regimen for Reducing the Incidence of Skin Tears.” International Wound Journal 11, (2014): 446–53. doi:10.1111/iwj.12326.

Kucharekova, M., P. C. M. Van De Kerkhof, and P. G. M. Van Der Valk. “A Randomized Comparison of an Emollient Containing Skin-Related Lipids with a Petrolatum-Based Emollient as Adjunct in the Treatment of Chronic Hand Dermatitis.” Contact Dermatitis 48, (2003): 293–99. doi:10.1034/j.1600-0536.2003.00119.x.

Shim, J.H., J.H. Park, J.H. Lee, D.Y. Lee, J.H. Lee, and J.M. Yang. “Moisturizers Are Effective in the Treatment of Xerosis Irrespectively from Their Particular Formulation: Results from a Prospective, Randomized, Double-Blind Controlled Trial.” Journal of the European Academy of Dermatology and Venereology 30, no. 2 (2016): 276–81. doi:10.1111/jdv.13472.

The Stratum Corneum: Protector of Your Internal Organs

Layers of skin, click to expand.

Curious to learn more about the layers of skin?

Want to know what the epidermis function – the epidermis is the outermost layer of the skin – is all about? Scientist, David Layton, takes a look at one of the integumentary system’s most important components: the stratum corneum.

The outer or top layer of skin, known as the stratum corneum, provides an essential physical barrier between external environmental agents such as harmful chemicals and microbes and our internal organs. It also controls the loss of body water through the epidermis to ambient air. The barrier function of the stratum corneum (SC for short) depends on a complex combination of skin structure plus biomechanical and biochemical processes. Key components of the SC are corneocytes, which are flat, non-viable cells with protein and lipid envelopes. The extracellular matrix between the corneocytes contains lipids (fats) arranged in lamellar, sheet-like structures or bilayers. In simple terms, the corneocyte and lipid matrix is often described as a “brick and mortar” construct, with the corneocytes representing the bricks and the lipids the mortar. Each strata, or layer, works together to form the stratum corneum. Cohesion of the corneocytes is facilitated by protein structures called corneodesmosomes that connect adjacent corneocytes.

Normal Functioning for Healthy Skin

New skin cells are constantly being produced, while at the same time corneocytes are simultaneously released from the skin surface to create a healthy, homeostatic balance. An important aspect of the normal shedding of corneocytes is the gradual degradation of near-surface corneodesmosomes via enzymatic processes. Weakened corneodesmosomes, which hold corneocytes together, facilitate their release to the exterior environment. Because corneocytes are very small, their discharge from the skin surface is not even noticeable. Nevertheless, it may come as surprise to know that shed skin cells are an important component of the organic matter content of indoor dust!

Proper functioning of the stratum corneum is maintained by the hydration properties of the SC, which primarily involve (1) the transport of water from within the deeper layers of the skin to the surface and (2) retention of water. The corneocytes contain a mixture of hydroscopic (water loving) compounds collectively referred to as the Natural Moisturizing Factor (or NMF) that absorb free or unbound water to maintain skin hydration. The lipid matrix in turn serves as a semipermeable membrane that helps control the transport of water from the hydrated inner skin layers to the exterior environment. The major lipids include ceramides, fatty acids, and cholesterol.

Dry Skin Formation (Xerosis)

The proximate cause of “cosmetic” dry skin that is manifested as visible flakes on the skin surface is the reduced action of hydrolytic enzymes in degrading the corneodesmosomes. As a result, corneocytes are released in visible clumps rather than single cells due to the continuing adherence to corneodesmosomes. A trigger event for the dry-skin process is typically low environmental humidity and temperature. Drying stresses in turn can disrupt the micro organization of the lipid matrix, which contributes to its dehydration. Changes in the level of the NMF in corneocytes can also exacerbate dry skin formation.

Dry Skin Management

Moisturizing lotions and creams on the market today contain a large variety of ingredients that can serve to inhibit the movement of epidermal water to air by forming an occlusive barrier (e.g., petrolatum) and/or absorb water (e.g., a humectant substance such as glycerin) to increase skin hydration. Diligence in monitoring the occurrence of dry skin and then proactively applying moisturizing lotions to both prevent and control skin dehydration can go a long way to restoring the healthy functioning of the stratum corneum.

Takeaways

  • A dehydrated stratum corneum can lead to dry skin formation and reduced barrier function, which can subsequently increase the risk of harmful exposures to environmental agents and negatively affect your overall skin anatomy.
  • Proactive management in detecting dry skin conditions and then actively treating the impacted areas with moisturizing lotions and creams is the key to restoring a healthy stratum corneum. 

References

Harding, C. R., A. Watkinson, A. V. Rawlings, and I. R. Scott. “Dry Skin, Moisturization and Corneodesmolysis.” International Journal of Cosmetic Science 22, no. 1 (February 2000): 21–52. doi:10.1046/j.1467-2494.2000.00001.x.

Proksch, Ehrhardt, Johanna M. Brandner, and Jens-Michael Jensen. “The Skin: An Indispensable Barrier.” Experimental Dermatology 17, no. 12 (December 1, 2008): 1063–72. doi:10.1111/j.1600-0625.2008.00786.x.

Dry Skin Care in the Desert Southwest: A Year Long View from Tucson, AZ

DSI and Skin Hydration in Tuscon, Arizona

I recently calculated values of the Dry Skin Index (DSI) and the water content of skin from 365 days of relative humidity and temperature measurements taken in my residence in Tucson, Arizona. As shown in the adjacent chart, the DSI and skin hydration levels follow distinct seasonal patterns. These patterns are controlled primarily by water vapor levels in outdoor air and the building properties of my residence (e.g., air exchange rates, water absorption/desorption from building materials, and indoor temperatures).

Changes in the Dry Skin Index and the skin hydration level over an entire year for a residence in Tucson, Arizona.

Changes in the Dry Skin Index and the skin hydration level over an entire year for a residence in Tucson, Arizona.

The most striking feature of the chart is the 7-month period from November to June when dry-skin stressors are the greatest. During this timeframe the DSI exceeds a value of 5 (indicative of moderate drying stresses) and the estimated water content of the outer layer of the stratum corneum (expressed in grams of water per mL of skin) drops well below a target level of 0.10 g/mL, which corresponds to a relative humidity level of 60% in ambient air (see the blog "The Target Hydration Level for Skin"). The highest levels of ambient water vapor occur during Tucson’s summer monsoon season, which begins in June or July when atmospheric conditions promote the transport of moisture from Mexico that subsequently increase humidity levels and trigger thunderstorms in southeast Arizona. Consequently both the DSI and skin hydration levels change rapidly, reducing skin drying stresses—but only until the monsoons end in September and drying trends begin again (as shown in the plots).

The climate of where you live has a direct impact on the drying stresses on your skin--and the Desert Southwest in the USA is no exception.

The climate of where you live has a direct impact on the drying stresses on your skin--and the Desert Southwest in the USA is no exception.

By monitoring the seasonal changes in skin stressors, I’m better able to prevent the occurrence of dry skin by proactively applying moisturizing lotions/creams and by operating a bedroom humidifier when indoor humidities are low. Historically though, my dry skin care was only initiated in response to dry skin—mainly because I was unaware of the impact of drying stresses on my skin. In fact, one of the surprises for me in studying the DSI plot was the long duration of the environmental stresses, which means that my personal skin care requires an ongoing commitment to moisturizer applications that correspond to the magnitude of external skin stressors.

Wrap Up

  • The unique, dry desert climate of Tucson, Arizona, produces a distinct seasonal variation in drying stressors on skin.
  • By monitoring those stressors, dry skin care can be adjusted to compensate for those stressors, helping to prevent undesirable conditions such as itchy dry skin and dandruff.
  • Although the focus of this Skin Care Blog is on Tucson, the climate of where you live as well as the building properties of your residence will produce a different set of seasonal dry skin stresses—and thus the need to monitor and adapt your personal skin care as appropriate.

Sunscreens on Amazon.com: What Dermatologists discovered

The summer months allow us to get outdoors and enjoy the sunshine!

However, we also know that it is important to reduce the associated exposures to ultraviolent (UV) radiation from the sun in order to prevent sunburns and on the long term, reduce skin cancer risks. Sunscreen application onto exposed skin is one of the primary methods for controlling UV exposures, but selecting a sunscreen is somewhat problematic because there are literally thousands to choose from. Moreover, what sunscreen characteristics would you use to compare brands?

Fortunately, a team of dermatologists (Xu et al., 2016) has systematically reviewed the top ranked sunscreens on Amazon.com and devised a set of 6 helpful screening categories that are based on both positive and negative consumer reviews (in order of importance):

  • Cosmetic elegance (ease of application, not greasy, moisturizing, etc.)
  • Product performance (how well it protects against sunburn, even with sweating)
  • Skin compatibility (e.g., does not affect sensitive skin)
  • Product ingredients (both organic UV absorbers and titanium dioxide)
  • Separate ratings (recommendations or reviews from other sources)
  • Affordability (expressed as price per ounce)

An additional consideration was whether a sunscreen adhered to recommendations published by the American Academy of Dermatology (AAD), which specify that a sunscreen should [1] provide broad spectrum protection against both ultraviolet A (UVA) and B (UVB) radiations, [2] have a sun protection factor (SPF) of 30 or higher, and [3] ensure water or sweat resistance for 40 to 80 minutes. The team reviewed the top 65 sunscreens out of the 6,500 listed on Amazon.com and surprisingly, 40% of the top tier products did not meet the AAD guidelines.

A sunscreen without water or sweat resistance is not an issue in situations where you’re not going to be swimming or sweating heavily. However, if your child is playing soccer on a hot, humid day, then you should definitely use a water-resistant sunscreen that will hold up for the entire game! Similarly, you don’t necessarily require a sunscreen with a moisturizer in it if you are encountering hot and humid conditions.

The affordability of sunscreens was not a major consideration in consumer reviews, but there can be major differences in the prices of sunscreens with similar consumer reviews/ratings. For cost-conscious consumers, Xu et al. (2016) list several low-cost, highly rated sunscreens on Amazon.com that provide up to 80 minutes of water resistance—their top five are:

  1. NO-AD Sunscreen Lotion SPF 45
  2. NO-AD Sport Sunscreen Lotion SPF 50
  3. Banana Boat Sunscreen Sport Family Size, SPF 50
  4. Australian Gold SPF 30 Spray Gel
  5. Banana Boat Sunscreen Spray SPF 30

Reference

Xu S, Kwa M, Agarwal A, Rademaker A, and Kundu RV. (2016). Sunscreen product performance and other determinants of consumer preferences. JAMA Dermatology. http://doi.org/10.1001/jamadermatol.2016.2344

 

What is the Dry Skin Index (DSI)?

Until recently no index has been available to monitor or gauge the magnitude of indoor humidity and temperature stressors related to the formation of dry skin.  In contrast, the UV Index, which represents the magnitude of ultraviolent radiation exposure from the sun, has been used to provide guidance to people regarding the need for sun protection for years.