Dead skin flakes in dust help remove ozone from indoor air.
An upside to dust. I'm Bob Hirshon and this is Science Update.
Apparently, household dust has a positive side. This according to chemist Charles Weschler of the UMDNJ Robert Wood Johnson Medical School in New Jersey.
Dust is partly made up of dead skin cells, and skin oils contain squalene—a chemical that scrubs ozone out of the air. Previously, Weschler's team found that airline passengers' skin oil helps reduce ozone levels in the cabin. This time, they studied dust from children's bedrooms.
And there's enough squalene in the dust in these bedrooms to be responsible for about 2 to 15 percent of the ozone that's typically removed in indoor environments.
Unfortunately, Weschler says you still need to vacuum, since the negative effects of dust outweigh this small benefit. But the findings will help scientists understand the complex chemistry of indoor air. I'm Bob Hirshon, for AAAS, the science society.
Making Sense of the Research
First of all, you heard correctly: dead skin cells are a significant component of household dust. Even though it's rarely noticeable to us, we shed dead skin all the time—roughly our entire outer layer of skin cells every two to four weeks. Indoors, those skin flakes fall on the floor and accumulate, along with all sorts of other particles, into what we call dust.
As for ozone, or O3—an unstable oxygen isotope—you might have heard about it in the context of the ozone layer, an ozone-rich part of the upper atmosphere that protects us from the sun's harmful ultraviolet radiation. But down at ground level, ozone is a pollutant, formed by the reaction between sunlight and particles from burning fossil fuels. Ozone is removed from the atmosphere in different chemical reactions, some involving sunlight, and others involving molecules like squalene, found in skin oils.
Before conducting this experiment, Weschler's team found that passengers' live skin removed ozone from simulated airline cabins. In this study, they looked at the effects of dead skin in household dust. They collected dust samples from 500 children's bedrooms and 151 day care centers in Denmark, and analyzed the samples for their squalene content.
They found squalene and cholesterol (another skin oil compound) in 97 percent of the samples. The bedroom dust's proportion of skin oil compounds was three times higher than that of day care center dust; the researchers speculate that this is because day care centers are cleaned more often and use more vinyl, dust-resistant surfaces. Overall, the researchers estimate that the squalene in dust could account for 2 to 15 percent of the ozone that's removed from the indoor air. Although cholesterol was also present from skin cells, the researchers say that cooking puts much more cholesterol in indoor environments than skin shedding.
So why should we keep dusting? Aside from keeping the house tidy, dust can trigger allergies, asthma, and lung inflammation. Dust also includes other particles that are toxic to humans. However, the study will be useful in the future, since it provides insight into what drives the ozone levels in indoor air environments.
Now try and answer these questions:
- What is squalene? How does it end up in dust?
- What did the study in the simulated airplane cabin show? Why was that important to this study?
- How does dust affect the levels of indoor ozone?
- Why is it useful to know how dust affects ozone indoors?
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