THE SITE

AIRNOW (www.epa.gov/airnow), an Environmental Protection Agency (EPA) site offers year-round air quality data and forecasts for close to 300 U.S. cities and national parks. New features on the site include forecasts of particle (soot) pollution, to which many people are sensitive.

THE GAUGE

The index factors in several types of pollution including ozone and particle pollution. Air quality is displayed via color codes: good (green), moderate (yellow), unhealthy for sensitive groups (orange), unhealthy for everyone (red), very unhealthy -- could cause more serious health effects (purple), and hazardous (brown).

THE GOOD

For people with respiratory diseases that can be exacerbated by pollution, at-the-ready air quality info beats waiting for a TV weather report. For information on the Washington area, click on "forecasts" on the home page, then scroll to the yellow rectangle over the Mid-Atlantic states.

THE BAD

Next-day data aren't posted until after 2 p.m. or later for some cities, and other cities don't monitor pollution levels at all. In Colorado, for instance, data are available for Denver, but not Colorado Springs. The EPA said other cities will participate in the future.

THE COUNSEL

Neither the site nor its link to the American Lung Association is very specific about what to do when air quality is poor. Experts say that when ozone levels are high, people at risk should reduce their outdoor activity, breathe through the nose, wear a mask if needed and increase vitamin C intake.