Current Conditions

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.

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:

 

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.