American Scientist

A recent visit to the lab of an chemical physicist prompted a combination of wonder, awe, and shock.

The research Solomon Bililign is conducting in his lab at North Carolina A&T State University in Greensboro is in atmospheric chemistry, which requires expertise in an array of scientific disciplines, including physics, chemistry, computer programming, and electronics. Knowing also what can go wrong with all the scientific instruments—each one a potential source of error—and then accounting for them takes additional expertise and a long time, too.

“We spent a whole year, actually, trying to calculate all the sources of error in this instrument,” Bililign told me, and that was just for one instrument. (n.b. concurrent error analysis for the entire system also took a year.)

All that effort isn’t to figure out the underlying science behind our worsening air quality and what that is doing to our health and life expectancy. That’s actually pretty well understood. Rather, the effort is to understand the underlying mechanisms that lead to that poor air quality, and researchers around the world are doing similar work to Bililign: using indoor smog chambers to recreate the atmospheric conditions of their locales of interest and then exposing that smog to ultraviolet light to mimic the exposure to sunlight. That's in order to study how the smog ages—changes over time—compared to how the particles were emitted, for example, from a vehicle's tailpipe (for a look inside an indoor smog chamber, see the image at the top of this post).

“So it’s not lack of understanding” of the underlying science regarding the health effects of air pollution, Bililign told me, “it’s a lack of the willpower to reverse the situation.”

The current situation is that the average life expectancy lost due to air pollution is about 1.8 years. Certainly it matters where you live as to how polluted the air is, and the latest research about life expectancy lost from air pollution in the United States is between 6 to 8 weeks.

Of course, there are plenty of caveats to these estimates, as there is with most any data-intensive research. Researchers themselves are quick to point out that human activities account for less than a third of the total amount of the finest particulate matter in our atmosphere, called PM2.5 for particulate matter that is equal to or smaller than 2.5 micrometers (or about 30 times smaller than the diameter of a human hair). That size makes those particles small enough to pass through our body’s natural filters and enter into our bloodstream. The presence of these tiny particles in our bodies has been linked to various life-threatening health conditions, including respiratory diseases, strokes, and heart attacks.

The natural sources of PM2.5 include wildfires, dust, and sea spray. Although we evolved around those natural sources, it’s not just the source but the amounts of these tiny particles that matter to our health. Global warming is associated with an increase in wildfires, contributing to greater amounts of PM2.5. Driving and road construction stir up a lot of dust, contributing to greater amounts of PM2.5. 

Even after decades of improvement in air quality here in the United States, each year we Americans emit millions of tons of fine particulate matter into the atmosphere by purposefully burning things, driving vehicles, and polluting. Recent reports, however, suggest that U.S. air quality is now slipping, with The Associated Press reporting their understanding that the Trump Administration has been lax in enforcing current regulations and will soon loosen regulations on emissions from vehicles and coal-fired electricity plants, which would put even more PM2.5 into the air.

“It’s a tradeoff,” Bililign says flatly, “when you think of good air quality, you are giving up certain economic benefits.”

We're also losing months—some of us years—of life.

Listen to a podcast based on a visit to Bililign’s lab.

Editor's Note: The original version of this post was updated with the n.b. above to clarify that concurrent error analysis for the whole system also took a year, and to include a link to the paper of that error analysis.