Polyvinyl chloride (PVC) is a common synthetic material used extensively in plumbing, heating and cooling, particularly in new construction, remodeling and HVAC system replacement. PVC is also found in a host of other products, including vinyl siding and flooring, carpeting, wiring insulation, roofing materials, doors, windows and trim. If you have a high efficiency furnace, or plan to install one, chances are good that your heating and cooling contractor will use PVC piping on the furnace's fresh air intake and exhaust ports.

The abundant use of PVC, especially in heating and cooling applications, has given rise to a new environmental concern, known as "outgassing."

Over time, PVC releases volatile organic compounds (VOC) into the air. According to the Environmental Protection Agency, this release, or outgassing, is suspected as a cause of health problems ranging from eye, nose and throat irritations to nausea, fatigue, dizziness and memory impairments, among others. The EPA states says long-term exposure to low levels of VOCs in water and air have been linked to permanent neurological, liver and kidney damage, and may play a role in reproductive disorders.

At room temperatures, PVCs are stable, but the chemicals used to manufacture it have a low boiling point. When heated (as would happen with a PVC furnace exhaust port or during a house fire), the release of VOCs into the air increases significantly.

"Some of our customers are now requesting alternatives to PVC materials to reduce the potential of indoor air and water contamination from VOCs," says Joseph Wood, owner of Boston Standard Plumbing in Dorchester, Mass. "Outgassing is a concern, especially for high-efficiency furnaces, which exhaust air to the outside. Homeowners need to be sure that the fresh air intake and exhaust ports are sufficiently separated, so potentially contaminated exhausted gases are not drawn back into the fresh air intake."

Wood says that other materials can substitute for PVC in residential heating, cooling and plumbing applications, but there could be a significant cost differential. "PVC is abundant and inexpensive, which is why it's used frequently," says Wood. "We offer stainless steel options for intake and exhaust ports, and while they're more expensive to purchase and install, they're incredibly durable and don't react to heat the way PVC can.

Wood points out that PVC is also used extensively in plumbing applications. "PVC can leach phthalates, lead and cadmium into fresh water systems," says Wood. "Even when PVC is used on the wastewater side, VOCs and contaminants can still be returned to the municipal water treatment facility, which isn't set up to remove VOCs completely from treated water.

According to Wood, "In older homes, plumbing systems are typically made from copper or cast iron. Both of these materials have some potential to react negatively with the water, but contamination usually occurs only when the system or its components begin to deteriorate." High acidity levels in water can also speed the deterioration of copper plumbing and fixtures, but water treatment plants are required to control for the acidity of their treated water to minimize the potential for plumbing damage.

"Copper, galvanized and cast iron plumbing components offer good alternatives to PVC for consumers who are concerned about the harmful effects of outgassing on their home's water quality." Wood points out that galvanized components will deteriorate faster, can cause rust stains on fixtures and are more susceptible to mineralization. He says that while copper is more expensive, it is likely to be a more satisfactory replacement plumbing material.