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GASP Press Release: Air Quality Forecasts Don’t Always Warn of High Air Pollution Days

Updated: Feb 26



Rachel Filippini or Joseph Osborne 412-325-7382


Recently southwestern Pennsylvania has enjoyed a bout of unseasonably warm weather giving residents an excellent final opportunity to enjoy the outdoors before winter cold sets in. Unfortunately, this warm weather has been accompanied by unhealthy levels of air pollution that were not predicted by air quality forecasts and thus went largely unnoticed and unreported in local media.

On Sunday, Nov. 15, air pollution in the Liberty-Clairton area was higher than anywhere else in the country.

For most of the day the U.S. Environmental Protection Agency’s (EPA) Air Quality Index (available at categorized Liberty-Clairton’s air as orange or unhealthy for sensitive groups.

Under these conditions EPA discourages sensitive populations (i.e. children, the elderly, and individuals with cardiovascular or respiratory conditions) from engaging in prolonged or strenuous outdoor activities.

From approximately 4 a.m. – 10 a.m. Sunday the air quality worsened to red or the “unhealthy” category.

When air conditions are in the red category all individuals are discouraged from engaging in prolonged or strenuous outdoor activities.

The Air Quality Index is intended to protect individuals from short-term health effects of exposure to significantly elevated pollution levels such as asthma attacks, heart attacks, and stroke. Unlike chronic health effects that may result from long-term exposure to even modestly elevated pollution levels, it is crucial that the public receive notification when pollution conditions are severe enough to cause immediate health problems.

This weekend, although air pollution levels were dangerously elevated, few were aware of the poor air quality. Forecasts often fail to alert people to the potential high hourly readings. Recent forecasts did not warn residents in Liberty-Clairton of these air action levels. This was not an isolated event, on Monday, Nov. 9, Liberty-Clairton air was in the red category for much of the day, but local media outlets failed to report this.

“It is imperative that people have access to the most current and accurate air quality information possible, especially when there is an action alert that puts sensitive populations at risk for adverse health effects,” GASP Executive Director Rachel Filippini said. “Local news outlets should be reporting actual air quality index levels as opposed to simply relying on forecasts which may be prepared days in advance and may not be accurate.”

What are the potential health effects of these unhealthy air levels?

The pollutant of greatest concern in the Liberty-Clairton area is PM2.5 or fine particulate matter. Fine particulates include both solid particles and liquid droplets that commonly result from fossil fuel combustion.

Fine particulates are linked to such health problems as asthma attacks and possible asthma onset, coughing and difficulty breathing, chronic bronchitis, decreased lung function, heart attacks, stroke, cancer, and premature death.

Children, the elderly and people with existing respiratory or cardiovascular ailments are especially sensitive to particulate matter.

What caused the elevated air pollution concentrations over the weekend?

In addition to fossil fuel combustion, particulate matter levels are influenced by weather and topography. In the river valleys of southwestern Pennsylvania, the levels of fine particulates often increase dramatically at night due to a meteorological phenomenon known as an air inversion.

During an inversion, the normal vertical temperature gradient is reversed such that the air is colder near the surface of the Earth. This can occur when, for example, a warmer, less dense air mass moves over a cooler, denser air mass. During an inversion instead of rising high in the air pollutants become trapped close to the ground, increasing ground-level exposures.

The Group Against Smog and Pollution, Inc. (GASP) is a non-profit citizens’ group working for a healthy, sustainable environment. Founded in 1969, GASP has served as a watchdog, educator, litigator, and policymaker on many environmental issues, with a focus on air quality in southwestern Pennsylvania.


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