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Indoor air can be deadlier than outdoor air, research shows

Indoor air pollution may be as much or more of a problem as pollution outdoors, according to new research.

Smoking indoors, lighting cigar
Bill O'Leary | The Washington Post | Getty Images

Smoke, fungal spores, and chemicals used in certain paints, varnishes and cleaners have been shown to be harmful to human health, and yet indoor air quality is not as well understood as pollution outdoors, according to a study published in the journal Science of the Total Environment.

"When we think of the term 'air pollution,' we tend to think of car exhausts or factory fumes expelling gray smoke," said study co-author Prashant Kumar of the University of Surrey. "However, there are actually various sources of pollution that have a negative effect on air quality, many of which are found inside our homes and offices. From cooking residue to paints, varnishes and fungal spores, the air we breathe indoors is often more polluted than that outside."

Of course, as the study notes, communities can take action to tackle the problem.

The team of scientists from Australia and Europe that wrote the paper is calling for greater efforts to monitor indoor air pollutants in real time, saying that doing so could bring serious health benefits.

Environmental sensors have become relatively cheap and don't require much energy. It would not be difficult to begin placing them inside buildings to monitor air quality, the researchers noted in their study.

Those who live in cities spend up to 90 percent of their time indoors — most of the air they are breathing is "indoor air."

Sometimes that air is similar to outdoor air, especially in well-ventilated buildings. But additional pollutants are killing significant numbers of people worldwide.

For example, the World Health Organization has said that household cooking with coal or biomass-burning stoves led to 4.3 million deaths in 2012, compared with 3.7 million deaths from outdoor air pollution.

Spores from mold are a common problem — particularly in old buildings or humid environments.

Kumar's previous research in the field showed that buildings near traffic intersections had substantially higher levels of pollutants indoors.

There is even a phenomenon known as "sick-building syndrome," where simply spending time in a polluted structure can cause symptoms of sickness.

In the study published Wednesday, the researchers said that a wide deployment of sensors could provide critical information. They acknowledge technical challenges — monitoring devices may not be sensitive enough to detect low but harmful concentrations of chemicals, and there are questions about how to handle the massive amounts of data that sensors could collect.