Where is this soot coming from? Combustion. Whether it is from poorly tuned motor-vehicle exhaust, power generation, industrial plants or residential fireplaces and power mowers, the uncontrolled release of this soot is dangerous. Recent research indicates that stronger national limits on soot pollution could prevent nearly 37,000 premature deaths nationwide every year — more than 1,500 of those in the Philadelphia metro area.
The EPA is required by law to update soot limits every five years based on the latest scientific and medical data, but the current annual standard hasn't been changed in 15 years. Public-health and environmental groups had to sue the agency for its foot-dragging. A federal court stepped in as a result of this legal action and directed the EPA to propose new limits this past June, with a final decision due by this December.
In one of only two national public hearings, parents, doctors, community members and clean-air advocates gathered in Philadelphia this week to tell the Environmental Protection Agency to strengthen national soot limits. The major polluters responsible for the soot that's in our air — car manufacturers, coal-fired power plants and oil refineries, for example — are flexing their political muscle for the weakest limits possible.
But as urban areas grow, things will only get worse. It is unreasonable to expect the public to walk around with masks and oxygen tanks, which is why national limits on fine-particulate matter must be updated. (The public can submit comments at Regulations.gov. Search "EPA-HQ-OAR-2007-0492-0456" and click "Comment Now!")
As a public-health physician, I endorse what many public-health and environmental groups are calling for: an annual limit of 11 micrograms of soot per cubic meter of air and a daily limit of 25 micrograms of soot per cubic meter of air. These concentrations — measures of the amount of soot that is allowable in a volume of air roughly the size of a box that a new computer comes in — are what's necessary to protect our health with an adequate margin of safety.
We will inevitably face the broken-record criticism that cleaning up air pollution stifles economic growth. Don't believe that lie — since the Clean Air Act was passed in 1970, gross domestic product has risen dramatically at the same time that air pollution levels have declined. But there's more work to be done, and the EPA should start with setting strong limits on soot pollution. Our lungs and our economy will benefit.
Dr. Tsou is an adjunct professor at the University of Pennsylvania Center for Public Health Studies and former Philadelphia health commissioner.
