Worst Pollutants Found Indoors, Scientists Say

People are exposed to more potentially harmful pollutants indoors--at home, in the office and in the car--than outdoors, scientists meeting in Anaheim said Wednesday.

Not all the sources of indoor pollution are known “but it seems probable that consumer products . . . and building materials” are major contributors, a five-year study by the Environmental Protection Agency said. “Common activities such as driving, showering, wearing dry-cleaned clothes, and passive smoking are also important sources of exposure.”

The study suggested that improving ventilation, replacing harmful chemicals in products, and developing new manufacturing techniques may be the most effective way to reduce potential health risks.

A Call for Research

“We need more resources devoted to research on indoor air pollution and, possibly, regulation,” said Lance A. Wallace, an environmental scientist for the EPA. Wallace made his comments at the American Chemical Society’s 192nd national meeting.

Although many of the chemicals involved in recent studies are known to be toxic or carcinogenic, the EPA research was not designed to evaluate the health risks caused by increased pollution indoors. Its goal, instead, was to develop and test methods to measure toxic chemical exposure.

The EPA study compared chemical levels in indoor and outdoor air samples, breath samples and drinking water samples from households in California, North Carolina, New Jersey and North Dakota.

Researchers found average indoor levels for 11 chemicals were two to five times higher than the average outdoor concentrations. For households with the highest exposure levels “the indoor values were 5, 10, or as much as 70 times the outdoor values,” according to a summary of findings.

Targeting the Sources

Researchers and regulators need to focus on indoor sources of harmful fumes--from paint cans and solvents to fabrics and cleaners--rather than the more visible “major polluters,” Wallace said.

The study found the greatest effect on toxic chemical concentration did not come from “living close to a chemical plant,” he said, “. . . but rather the building materials, consumer products and personal activities of the people” living inside the house.

Little difference in average chemical levels of homes was found in different parts of the country, from industrial centers such as Los Angeles to the small, agricultural town of Devils Lake, N.D.

The worst household dangers identified so far include smoking, living with a smoker, using air fresheners, moth crystals, aerosol sprays and storing paints and solvents, Wallace said.

A related study--also presented Wednesday--added bathing and doing the dishes to the EPA’s list of activities that can increase indoor pollution.

Danger in the Shower

Julian B. Andelman, professor of water chemistry at the University of Pittsburgh, found less chemical exposure from drinking contaminated water than in using it to wash the clothes or take a shower.

Experimenting with a model shower and common water pollutants, Andelman found that the toxic chemicals evaporated--or volatilized--into the surrounding air. Increased concentrations of the chemicals build up in the shower and spread through the home, he said.

The amount of the chemicals that vaporizes increases with longer and hotter showers, the scientists found.

“I tell my friends to take quick, cold showers,” Andelman said.

Another source of increased exposure to harmful substances is the daily commute, another study concluded.

Tests Inside Cars

Scientists from the South Coast Air Quality Management District put battery-operated air testers inside automobiles to determine the occupants’ exposure to eight organic chemicals and 34 metals.

Inside the cars, levels of airborne benzene, toluene, lead, nickel, chromium and manganese were three to five times higher than the average outdoor concentrations, the researchers found.

Concentrations of other substances--including chlorinated hydrocarbons--were not significantly different from the ambient levels.

The researchers concluded that “air toxic concentrations within commuting vehicles in the Los Angeles Basin may . . . constitute a significant portion of an individual’s total air toxics exposure.”

A stop at the self-serve pump does not help either, Wallace said. “That three minutes of exposure (to benzene, a suspected carcinogen) equals your exposure for the rest of the day, if you’re not a smoker,” he said.

Both driving and filling up were included on the EPA’s list of activities “strongly associated with increased breath levels or personal (household) air exposures to one or more toxic chemicals.”

The research presented Wednesday--and other similar findings--recently prompted the EPA to create “an indoor air group” to study regulatory options, Wallace said. Still, he said, spending for indoor pollution research is about a hundredth that for outdoor pollution.