Fine particulates — the tiny particles known as “PM2.5,” measuring 2.5 micrometers or less in diameter — are a worldwide killer. The micro-sized particles can avoid the body’s defenses and enter the bloodstream, and they carry an increase to the risk of asthma, heart attack, and stroke. In a multimedia story, The New York Times graphically displayed the concentration of PM2.5 in some of the world’s most polluted cities, along with a drop-down that lets you compare those extremely polluted locations to your own location (see: “See How the World’s Most Polluted Air Compares With Your City’s,” by Nadja Popovich, Blacki Migliozzi, Karthik Patanjali, Anjali Singhvi and Jon Huang).
“In the United States, which has some of the cleanest air in the world, fine particulate matter still contributed to 88,000 premature deaths in 2015 — making this pollution more deadly than both diabetes and the flu,” reports the Times. “And pollution in America has worsened since 2016, reversing years of decline.”
An airtight home can help protect occupants from polluted outdoor air. That’s according to a presentation by Brett Singer, a Staff Scientist and Principal Investigator in the Energy Technologies Area of Lawrence Berkeley National Laboratory. Singer heads up the Indoor Environment Group at LBNL and is co-leader of Indoor Air Quality research in the Residential Building Systems Group. One of Singer’s focus areas is the fine particulates generated by indoor activities such as cooking, burning candles, or smoking indoors. While those indoor sources fall well short of the outdoor concentrations in even a moderately polluted U.S. city, it’s important to realize that people spend most of their lives indoors — so indoor pollution can be a significant factor in their overall exposure.
In a presentation at the Building Science Summer Camp in Westbrook, Mass., Singer observed that homes are getting tighter — and that airtightness reduces indoor exposure to outdoor pollutants. Filtration of the incoming or indoor air also helps, but studies show that indoor filters are often turned off by occupants. Good labels on the filter controls are helpful, research indicates.
But indoor activities can also generate PM2.5 pollution. Singer and his colleagues at LBNL have taken a close look at the pollutants created by cooking (see: The Science of Kitchen Ventilation – JLC 2/15, by Ted Cushman). “In studying hundreds of California homes, Singer and his colleagues have learned that when people cook with gas ranges, quantities of indoor-generated pollutants often measure higher nowadays than pollution levels in the outdoor air,” says the report. The key to controlling occupant exposure to those cooking particles is effective ventilation, according to Singer.
