Opening your windows doesn’t help reduce indoor air pollution

Airing out our homes might not be as effective as we think. Chemicals released by cleaning or cooking can stick to walls, furnishings and other surfaces instead of wafting out when we open a window.

“It’s quite a surprise,” says Chen Wang at the University of Toronto, Canada. “We thought that when we diluted the volume of the air in the house [these] may just get removed and mix with the outside air.”

She and her colleagues studied the persistence of 18 common indoor chemicals inside a mock house. Some of these, such as carboxylic acids, appear to be released by cooking. We don’t know yet if they are harmful to human health when they accumulate in the home.

These chemicals are all volatile, meaning they can evaporate into air, but the researchers wanted to see if they can linger on surfaces too. The team asked volunteers to mimic real-life activities in the house, such as cooking and cleaning, and then measured the levels of these 18 chemicals in the air.

The researchers then ventilated the home by opening its windows and doors and then measured the airborne levels of the 18 chemicals again after they were closed. The team found that ventilation for 15 or even 30 minutes made little difference – the chemicals soon reached similar levels in the air as before.

Wang says the airborne levels of these chemicals in our homes aren’t high enough to be concerning, but that they are likely to be higher after cooking or cleaning.

“Modern houses are becoming more air-tight as we try to conserve energy,” says Frank Kelly at King’s College London. This may be bad for our air quality unless homes are built with mechanical ventilation systems, he says.

Journal reference: Science Advances, DOI: 10.1126/sciadv.aay8973

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