Michael Stepaniak has at least three good reasons why families should drop off hazardous household chemicals at the Butler County Fairgrounds on Aug. 26.

Mr. Stepaniak works for the Pennsylvania Resources Council, which administers the annual collection program with a host of cosponsors. For $2 per gallon, residents can safely get rid of items ranging from out-dated pool chemicals and pesticides to half-empty paint cans and acid-filled car batteries.

"There are a lot of dangers associated with improper disposal of these materials," Mr. Stepaniak said. "They can pollute supplies of groundwater. If they are poured down storm drains, they can end up in waste water treatment plants."

"If you dispose of containers with the regular trash, they can endanger sanitation workers," he added. Mixed in the back of a garbage truck, the materials can ignite or give off deadly gases.

"They can be a danger to pets or children. If there is a fire, fumes can injure first responders."

Aug. 26 will mark the third year for the collection effort in Butler County, which, so far, has brought in more than 33 tons of hazardous waste for safe disposal. That number is part of the more than 425 tons of material collected since 2003 at 15 collection sites across Southwestern Pennsylvania.

Materials are recycled, incinerated or buried in special landfills.

Kitchens, bathrooms, basements, garages and garden sheds are the most likely places to find substances requiring safe disposal, organizers say.

The fairgrounds drop-off site is on the north side of Route 422 in Prospect and Franklin. Hours are 9 a.m. to 1 p.m. The $2 per gallon fee, which Mr. Stepaniak said covers only a fraction of the disposal cost, must be paid in cash.

While the site is most easily accessible to people living in Butler, Lawrence and northern Allegheny counties, the disposal service can be used by all Pennsylvania families.

The full name of the group sponsoring the program and others around the region is the Southwestern Pennsylvania Household Hazardous Waste Task Force. Most of the program expenses are covered by corporate and foundation contributions and grants from the state Department of Environmental Resources.

The task force needs volunteers to assist with the Butler effort.

Volunteers can work either a full or a half day, directing traffic, serving refreshments and collecting surveys, according to Sheryl Kelly, coordinator of Butler County Recycling and Waste Management, one of the agencies participating in the task force. "They will get fed and get a free T-shirt," she said. "They will not be handling hazardous waste."

People interested in volunteering can call the Resources Council at 412-488-7452 or visit its Web site at www.swpahhw.org.

The Web site also has information on what materials will or will not be accepted.

While hazardous waste collection days provide one important way to handle dangerous materials, families can follow other environment-friendly practices, Ms. Kelly said.

Many garages will accept used motor oil, she said. The material then can be used as heating fuel in waste-oil burners.

While they charge a recycling fee for the services, tire dealers and garages will accept old tires.

The amount of material collected has grown each year, Ms. Kelly said. About 400 families brought items to the fairgrounds last year. "We hope to see more households taking part this year."

Mr. Stepaniak had several suggestions for those planning to bring in materials for disposal:

Don't mix chemicals.

Check containers to make sure they are not leaking before transporting them.

Pad glass containers to avoid breaking them.

If you are not sure about the contents of a can or bottle, mark it "unknown."

"Finally, don't smoke in the car while you are carrying hazardous materials," he said.