Heat wave brings more smog

Chantel Streeter and her son, Omar, try to keep cool while waiting for a bus in west Baltimore on June 21, a day when smog hit levels deemed unhealthy for everyone.

With temperatures predicted to top 100 degrees today and stay in the high 90s into next week, air-quality forecasters are warning that smog across much of Maryland likely will reach unhealthful levels for children, older adults and anyone with breathing or heart problems.

Smog, or ground-level ozone pollution, is expected to hit "Code Orange" levels through Sunday in the Baltimore metropolitan area, according to Clean Air Partners, which publishes air-quality forecasts prepared for the Maryland Department of the Environment and the Metropolitan Washington Council of Governments.

Ozone is formed when motor vehicle exhaust and emissions from power plants, factories and other sources, including lawnmowers, boats and some household products, "cook" under strong sunlight on hot, relatively wind-less days.  Inhaling ozone-laden air can cause shortness of breath, coughing, wheezing, fatigue, headaches, nausea, chest pain, and eye and throat irritation. Five to 20 percent of the population is especially sensitive to ozone, according to the Environmental Protection Agency.

(Code Orange is used when ozone levels in the air are expected to be tolerable for most healthy people but high enough to cause breathing problems for those sensitive groups, and they are urged to limit outdoor activities.)

TheWashington, D.C.area and the Eastern Shore also have Code Orange forecast through the weekend. 

Anyone looking for cleaner air to breathe over the weekend while enjoying the outdoors might want to try western Maryland, where Code Orange is called for on Friday but smog is expected to abate to moderate levels on Saturday and Sunday.

We're entering the peak smog season for much of Maryland.  After a mild May, there've been four days in June when ozone pollution in the Baltimore area reached unhealthful levels for sensitive groups of people, and one - June 21 - when air quality was bad enough (Code Red) to warn everyone to limit outdoor activity.  Last year this time, there'd five bad air days, two polluted enough to be unhealthy for everyone.

July is typically the worst smog month.  Last year, ozone hit levels unhealthful for at least sensitive individuals on 16 out of 31 days.  Maybe a good time to head for the mountains, or at least stay cool and airway-free in someplace air conditioned.

To get hourly updates on air-quality readings near you, go to Clean Air Partners' web site and click on the "Current" tab over the map of Maryland.  Check out how murky the air is around the state by clicking on the "Haze Cams" tab.

And for those who'd like to do their part, however small, to make the air healthier to breathe, experts advise limiting driving, refueling and cutting the grass with gas-powered mowers.  For a longer list of tips, go here.