Very Poor Air Quality Expected In Montco Again Tuesday, Officials Say

An air quality alert has been issued again on Tuesday in Montgomery County as temperatures soar into the mid-90s and ozone levels rise.

The "code orange" alert, which also covers Philadelphia, Bucks, Chester, and Delaware counties, indicates that outdoor activity is unhealthy for sensitive groups.

"High ozone levels are most common during summer months when there are long days with plentiful sunshine and high levels of ozone precursors combine," the Pennsylvania Department of Environmental Protection said.

That usually means July or August, not May.

Ozone is formed when chemicals common in pollution, like nitrogen oxides and other volatile organic compounds, react with sunlight.

Car exhaust and industrial air emissions are the most common causes of ozone, which explains why the Philadelphia area, filled with factories and dense highways, is the most impacted in the state.

You can help reduce ozone levels by taking the following measures, the state says:

• Driving less by carpooling or using public transportation

• Combining errands to reduce vehicle trips
• Limiting engine idling
• Refueling cars and trucks after dusk
• Conserving electricity by setting air conditioning to a higher temperature and turning off lights that are not in use

Similar alerts were issued along several of the eastern seaboard's major cities and suburban areas as the heat wave continues.