Remember those sunburnt summer days when the temperature hovered in the 90s?

	John Heller, Post-Gazette Swimmers at Sandcastle's Wave Pool in West Homestead beat the heat. Click photo for larger image. Check the forecast Get hour-by-hour and five-day forecasts on our weather page.

It hasn't been that hot here in nearly three years, but it could be today or later this weekend.

Temperatures of 90 or higher are a possibility today and tomorrow, said Wayne Rumburg, a meteorologist with the National Weather Service.

The Allegheny County Health Department issued an alert yesterday indicating that the expected high temperatures could pose serious problems for the elderly, young children, or people who have heart or respiratory problems, are overweight or who work or exercise outdoors.

The state Department of Environmental Protection also declared today as the area's first Air Quality Action Day this season for high ground-level ozone levels. The alert was issued for Allegheny, Armstrong, Beaver, Butler, Fayette, Washington and Westmoreland counties.

High ozone levels can trigger breathing problems, particularly among the elderly, young children or people with asthma.

Ozone levels are expected to remain high in the area tomorrow, and levels of unhealthy soot -- microscopic airborne particle pollution -- also will be elevated, DEP officials said.

They recommend limiting certain activities that contribute to ground-level ozone, the prime component of smog. Residents are asked to carpool or use public transportation and to refuel their vehicles or cut grass early in the morning or after 7 p.m.

A bit of cloud cover could make the temperatures a few degrees cooler Sunday and Monday, Rumburg said. But Tuesday also could be a 90-degree day.

Temperatures haven't been 90 or above 90 in Pittsburgh since Sept. 9, 2002, when the high was 91, Rumburg said.

Despite the three-year lapse in 90-degree weather, temperatures at that level, at least for a few summer days, are typical for this area. So a weekend of sweltering temperatures would reflect a "normal Pittsburgh summer," Rumburg said.

Even before summer officially began Tuesday, the area had a taste of warmer weather. In the first half of the month, highs were in the upper 80s on several days.

The humidity on some of those days reached 90 percent or more. Lower humidity is expected during the next few days, but the weather still will be uncomfortable, Rumburg said.

Older people are especially at risk from the high temperatures, in part, because they have less ability to sweat, which carries away body heat.

The Health Department recommended that people check on elderly or infirm family members or friends, particularly if they do not have air conditioning.

Allegheny County's Area Agency on Aging has directed personnel to check on elderly people who receive nursing care or other assistance in their homes, said Mary Kay Meanor, a spokeswoman for the county Department of Human Services.

The county Health Department also recommended these steps to minimize the risk of heat-related illness:

Stay indoors, preferably in air conditioning. Those who lack air conditioning are advised to visit places that are air-conditioned, such as a senior center, theater, mall or neighbor's house. If no air conditioning is available, a cool bath or shower is more effective than a fan for lowering body temperatures.

Drink plenty of fluids. Avoid alcoholic or caffeinated drinks, which actually cause fluid loss, and hot foods or heavy meals, which add heat to the body.

Wear lightweight, light-colored and loose-fitting clothes. A wide-brimmed hat provides shade and helps keep the head cool.