Pittsburgh Post-Gazette

Complicate­d

Pittsburgh’s air quality is

- The writer is a visiting associate professor of economics at Carnegie Mellon University and the National Bureau of Economic Research.

Both John Graham, in a July 8 op-ed column “Pittsburgh, Still Polluted,” and Joe Duckett, in a July 17 letter “The Region’s Air Quality Has Vastly Improved,” make important arguments regarding air quality in the Pittsburgh region. However, both writers omit critical details in making their case.

First, Mr. Graham argues that Pittsburgh’s air remains stubbornly polluted. He substantia­tes his position by citing readings from the air pollution monitoring stations throughout Western Pennsylvan­ia. What Mr. Graham fails to recognize is that air quality monitors have historical­ly been located to detect, or catch, violations. That means, of all the places a regulator might place a monitor, they are more likely to put it where the air is dirty than where the air is consistent­ly clean. Because local, state and federal regulators often operate under the constraint­s of limited public budgets, this approach makes sense. However, the tendency to place monitors in areas likely to violate air quality standards significan­tly hampers our ability to infer air quality conditions in un-monitored neighborho­ods. There aren’t monitors “all over.” They are in particular spots and it is very difficult to draw conclusion­s about air quality elsewhere.

Second, Mr. Duckett correctly points out that air quality has improved in Allegheny County. However, Mr. Duckett’s stance, that the correct benchmark for gauging air quality is the National Ambient Air Quality Standards, is problemati­c. The NAAQS are set, using findings from scientific research, to protect human health and welfare.

However, the body of evidence from public health studies suggests that the air pollutants Mr. Duckett refers to do not have a safe level. This means that risks to health from inhalation exist at levels below NAAQS limits. Thus, although it is nice to not repeatedly violate the NAAQS, compliance doesn’t eliminate risk.

In summary, both writers make valid points in their respective commentari­es. However, both writers leave out crucial details in their characteri­zations of air quality and the risks to health associated with it. NICHOLAS Z. MULLER

Squirrel Hill

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