Nice piece by Nicola Twilley, co-host of Gastropod:

“So there is a big question here,” Marina Vance pointed out. “If all these studies have found an association between outdoor air pollution and a decrease in life quality and life expectancy, but we’re not outside, how does that relationship still hold?”

One possibility is that the brief moments we spend outdoors have an outsized impact on our health. Another consideration is that outdoor pollutants can and do come inside. But one homechem researcher, Allen Goldstein, recently co-authored a paper that suggests a fascinating inversion. The dominant source of VOCs in Los Angeles is now emissions from consumer products, including toiletries and cleaning fluids. In other words, vehicle emissions have been controlled to such an extent that, even in the most car-clogged city in America, indoor air that has leaked outdoors may create more smog than transportation does.

It’s true — some surveys done in the last couple of decades show that people in North America spend, on average, 90% of their time indoors. It’s unlikely that our air pollution exposures — measured as ambient concentrations at central sites, far from where we live and spend time — capture what’s really going on.

One point of contention with this article — despite some nice historical thinking on the relationships between indoor and outdoor air, there was no mention of the very large exposures that continue in the developing world, where solid fuels like wood, grass, dung, and coal are used indoors. A substantial oversight.

Update: Nicola Twilley wrote on twitter that mention of the developing world didn’t make the final version.