Mary Mullen said that phones at the Philadelphia Corporation for Aging have been ringing off the hook for the past couple of days. And with temperatures expected to rise, she said she expects more phone calls.

To accommodate demand, PCA has activated its call center, Heatline, and will extend the hot line's hours today and tomorrow - from 8:30 a.m. to midnight - an additional seven hours.

The service counsels callers about precautions to take in the heat and ways to detect signs of heat stress.

"There had been a burst of phone calls [Saturday]," said Mullen, a Heatline supervisor, who added that this is the first time in recent memory that the call center has been activated so early in the year.

"So you can imagine [what the phone calls will be like] in the next couple of days," she said.

The call center was activated on Saturday after the city issued an excessive heat warning, effective through tomorrow, said Jeff Moran, spokesman for the Medical Examiner's office.

He said that once temperatures rise to high levels, the PCA's Heatline and the Department of Health's summer heat programs start up.

Yesterday at PCA, Mullen said that she and other staff members fielded phone calls mostly from concerned neighbors of elderly people, who, along with children, are at risk of injury or death when subjected to excessive heat for extended periods.

Moran said that no heat-related deaths have occurred so far this year.

With any luck, there won't be any today or tomorrow as temperatures climb to the mid-to-upper '90s but will feel like 105 degrees because of an unbearable humid air mass, according to the National Weather Service.

At night, temperatures will not drop below 80 degrees in some locations, like Center City.

Here are tips provided by PCA to help beat the heat:

* Use air-conditioning during the hottest part of the day or go to an air-conditioned location.

* Make sure fans are not being used in a closed-up house.

* Take a bath or shower.

* Wear lightweight clothing.

* Reduce activity, eat light and drink lots of water.

* Avoid caffeine and alcohol.

For more information, call PCA's Heatline at 215-765-9040. *