In what it calls an unprecedented effort to help protect children from toxic air pollution, the U.S. Environmental Protection Agency yesterday announced it will monitor air outside 62 schools in 22 states, including four in Allegheny County.

The announcement follows a USA Today investigation that examined the impact of industrial pollution on air outside schools nationwide, using the government's model for tracking toxic chemicals.

In findings published in December, the newspaper concluded that hundreds of schools have air pollution that might threaten students' health.

EPA officials said the agency is beginning with a "subset" of schools so that it can begin monitoring as quickly as possible. The list includes Clairton Education Center, South Allegheny Middle/High School and Sto-Rox Elementary and Middle schools.

Two other schools in Pennsylvania also are on the list, one in York County and another in Berks County.

The EPA is focusing first on schools near large industrial plants as well as some schools in urban areas where emissions come from large and small industries, cars, trucks, buses and other sources. The results will help to determine whether additional schools need to be monitored.

"EPA, state and local officials are mobilizing to determine where elevated levels of toxics pose a threat, so that we can take swift action to protect our children at their schools," said EPA Administrator Lisa P. Jackson.

Allegheny County Health Department spokesman Guillermo Cole said the EPA will provide the monitoring equipment and the county will take samples every six days for 60 days. The samples then will be sent to a lab for analysis.

The EPA is looking at toxic air pollutants, also known as hazardous air pollutants, which are known or suspected to cause cancer or other serious health problems. These typically come from nearby sources. The exact pollutants to be monitored vary by location.

The Allegheny County Health Department for years has had monitoring equipment at both the Clairton Education Center and the South Allegheny Middle/Senior High School. It also has a site in Stowe, about a mile east of Sto-Rox Elementary.

The EPA monitoring, however, will cover more air toxics than county monitoring does.

As a result of the USA Today report, the Allegheny County Health Department last month did some air monitoring inside in Sto-Rox Elementary School as well as at Highlands High School, which was among schools mentioned in the USA Today report.

Mr. Cole said the Sto-Rox monitoring showed that the air inside the school had higher benzene levels than the air outside. The school since then has increased the rate of fresh air flowing into the building and ordered charcoal filters.