The indoor environment & skin

With the colder months upon us, temperatures begin to plummet, and statistics show people are spending up to 90 percent of their time inside¹. With our doors and windows closed, we can trap indoor pollutants inside our homes, and activities like burning candles or log burners, or cooking and cleaning as we set up for the holiday season can release pollutants themselves. Combustion events often release ultrafine particles of soot and carbon as well as gases like NO₂. The scents in candles, air fresheners, diffusers and room sprays are likely to contain volatile organic compounds (VOCs), and the chemicals in cleaning products can also give off gases like benzene and formaldehyde. The pollutant level indoors can be up to 5 times worse than outdoors².

Air pollution isn’t the only element of air quality to be conscious of in the winter. Modern air conditioning and heating can potentially increase exposure to dry air. Low humidity is usually associated with heaters based on convection technologies; as indoor air is warmed, relative humidity usually decreases. As air heats, it expands and gains the ability to hold more moisture, which overall reduces the relative humidity, expressed as a percentage. When the air is too dry, it can trigger irritation and flare-ups in a range of skin issues³.

The structure of skin

Skin is constantly exposed to various environmental stimuli. The top of the epidermis - the stratum corneum - is the skin’s protective barrier. Its primary role is to prevent foreign matter from getting into the body while keeping water inside the skin cells from leaching out. The stratum corneum contains ceramides, which play an important role in skin health. This barrier is comparable to a brick wall, with the skin cells as the bricks and the ceramides as the mortar, forming a protective layer. If the stratum corneum is weak, ‘cracks’ begin to appear in the ceramides.

Impact of dry air on skin

The ‘cracks’ in the ceramides can be caused by dehydrated skin, and in turn this weakened layer means water can evaporate easily from the skin in a process called trans-epidermal water loss (TEWL). This natural process occurs when water makes its way from the dermis (the deepest layers of skin) and passes up to the epidermis where it evaporates from the stratum corneum into the atmosphere. However, cold dry air can increase the rate of trans-epidermal water loss. Excessive water loss results in dehydration and can lead to symptoms including dry, rough, flaky, itchy and inflamed skin. And it’s a vicious circle - when dry air takes moisture from our skin, its structure changes. Those changes make our skin less able to hold onto moisture.

There are some notable conclusions from large-scale cohort studies:

• Exposure to particle pollution over the long-term is an independent risk factor for developing atopic dermatitis (AD), even an increase of 1ug/m³ correlates to a 42% uptick in risk of development of AD⁴
• Pollution exposure including PM2.5 and PM10 independently increases risk of developing Psoriasis⁵
  • 1ug/m³ increase in the long-term average concentrations of PM2.5 or PM10 correlates to a 65% and 30% increase in risk of developing Psoriasis respectively⁶
• Accelerated aging has been correlated with particulate matter (PM) pollution exposure – manifesting in increased pigmentation spots, wrinkles in the upper lip & forehead⁶
• Cooking with solid fuels is associated with 5-8% more severe wrinkle appearance on face, 74% increased risk on fine wrinkles on hands⁷ - the inference in this research is that this was a result of the pollution generated by fuel combustion for cooking
• Another study suggests that air pollution is significantly correlated to signs of aging – including pigment spots and wrinkles. Any increase in exposure to soot and traffic particles has been linked to experiencing 20% more pigment spots on face⁸

Managing the indoor environment – humidity & air pollution

There are many management mechanisms for dry skin or other humidity-related skin issues, and increasingly, for pollution exposure – from creams and serums to increasing water intake to covering skin to reduce exposure to colder or polluted air. However, tackling the problem of indoor air quality – both pollution and humidity level – at the source can be one way to manage your environment through the winter months.

With humidifiers touted globally as a solution to dry air-related skin issues, Dyson set out to understand the science behind skin moisture level and explore whether humidification has a tangible positive impact on skin through robust, scientific testing

Researching the impact of humidifiers on skin moisture

Results from a study commissioned by Dyson demonstrate that humidifiers can help maintain the skin’s moisture level – part of Dyson’s commitment to understanding air quality in homes and the impact of Dyson technology on related issues.

As a first step in understanding the impact of Dyson humidification technology on skin over a set time-frame, our scientists undertook a scientific research⁹ comparing skin that had been exposed to air humidified by a Dyson Purifier Humidify+Cool machine (set to a relative humidity of 55 percent), with skin that had been exposed only to dry air (at 25 percent relative humidity). Each individual’s forearms were exposed to the different conditions for three hours, after which the forearm exposed to dry air was introduced into the humidified environment⁹.

Following this test, the researchers collected data on three different parameters:

-          Hydration level of stratum corneum (the outer most layer of the skin)

-          Skin barrier function (by measuring trans-epidermal water loss or TEWL)

-          Water content and the stratum corneum thickness

The research has shown that the Dyson Purifier Humidify+Cool machines resulted in higher skin hydration over a three-hour period compared to dry ambient air, particularly if the skin was previously exposed to dry ambient condition. The water content and stratum corneum thickness tended to increase over the 3 hours of humidifier use, demonstrating better moisturization of the top layer of the epidermis

Tips for choosing an air treatment device

-          Take room size into account

To ensure you benefit from a humidifier, consider the humidity of the whole room. Select a humidifier that has a fan function to project humidified air. It’s crucial to ensure an even humidity level across the room so that you benefit from the increased moisture wherever you are in that space.

-          Keep it clean!

All humidifiers must be kept clean to prevent the build-up of mineral residue that naturally forms over time after exposure to water. Water types vary globally – if you live in a hard water area, you may need to clean your machine more regularly. For some humidifiers, cleaning can be quite tricky, with lots of hard-to-reach parts to clean. Others have regular cleaning alerts or simple cleaning processes – so be sure to get familiar with the manufacturer’s guidance.

-          Think hygiene

It’s well known that standing water is a fertile ground for bacteria to breed. This is no different within the tank of a humidifier. Some machines don’t effectively treat the water within the tank, so look out for those that use technology such as UV to kill any bacteria in the water¹⁰, before it is projected into the room.

-          Maintaining a constant optimum air quality / humidity level

As technology has advanced, most humidifiers have an auto mode that helps maintain the right humidity for you, so you don’t have to worry about it. The auto mode reads the humidity of the room and controls the humidity level in accordance.

-          Air quality is key

Humidity isn’t the only aspect of air quality that can impact skin. A number of humidifiers combine air purification with humidification to manage moisture and pollutant levels simultaneously. Look for purifiers with HEPA-certified filtration, fully-sealed filters, and a high percentage of pollutant capture – both particle and gas, including Formaldehyde.

-          Choose fully sealed

Many purifiers have HEPA filters, it’s a very common filter standard to meet. This means that when tested alone, sealed into the test machine, the filter can capture 99.97% of particles as small as 0.3 microns¹¹. But the filter isn’t always properly sealed. Air follows the path of least resistance, which means dirty air can simply bypass the filter and be projected back into the room. Fully sealed filtration ensures that the whole product captures particles properly. At Dyson, we speak about full-machine HEPA, which means the whole product, not just the filter, is sealed and captures pollutants to the HEPA H-13 standard.