Code orange smog alert for Tuesday

In addition to sweating through temperatures in the 90s on Tuesday, Philadelphians may find it tough to breathe.

Forecasters are predicting a "code orange" air-quality day based on levels of ground-level ozone, which is a chief component of smog.

That means people with asthma and the elderly should take it easy and restrict outdoor activity. Even healthy children and adults may wish to avoid heavy exertion outdoors.

The forecast, publicized by the American Lung Association, is based on data from the Pennsylvania Department of Environmental Protection.

"Orange" days are those with ozone measurements above 75 parts per billion over an eight-hour period. In the Philadelphia area, such days typically occur about 10 times a year - far less than in the past. - Inquirer staff