Academic journal article Asia - Pacific Issues

Looking for Pollution Where the People Are

Academic journal article Asia - Pacific Issues

Looking for Pollution Where the People Are

Article excerpt

When we think about air pollution, we visualize the smog that envelops our cities or industrial smokestacks belching noxious fumes. Concern about these kinds of obvious pollutants has generated widespread support for controlling air pollution.

But if the principal goal of pollution control is to protect public health, this focus on outdoor air pollution, and on the largest outdoor sources of emissions, fails to do the job. For to affect health, we must reduce people's exposure to healthdamaging pollutants in the air they actually breathe. These pollutants come, to a great extent, from relatively small localized sources that are, literally, right under our noses: cigarettes, spray cans and dry-cleaned clothes, for example. And, most often, these are indoors.

In fact, most of our exposure to pollutants occurs indoors-inside homes, vehicles and workplaces. The growing awareness of the importance of small indoor sources reveals both another set of important pollutants and a new ordering of priorities for protecting public health. Indeed, acknowledging that health-damaging pollutants should be measured where the people are promises a revolution in the way air pollution sources, victims and control measures are evaluated.

Monitoring the Safety of the Air We Don't Breathe

In the United States, seven so-called "criteria" pollutants are widely monitored and regulated by the Clean Air Act. Included are particulates (solid or liquid particles suspended in the air that cause or worsen respiratory illness), carbon monoxide (a gas that damages the heart), and nitrogen dioxide (a gas associated with respiratory illnesses). A large national network of several thousand outdoor monitors measures compliance with the standards.

The United States has served as a model for other nations where similar standards have been established. But the current pattern of monitoring and regulation may not directly address the locations and types of pollutants with the most damaging health impact.

Current standards apply to outdoor levels of pollution where measurements are most easily made-typically the rooftops of public buildings. These locations are chosen for convenience, security, geographical spread and general congruence with population distribution. Most people, however, do not spend much time outdoors, particularly in temperate developed countries. In the United States, for example, less than 10 percent of the population's time is spent outdoors. Even in developing countries, 70 percent or more of the population's time is spent indoors.

How closely do the monitored outdoor concentrations of pollutants match the actual concentrations encountered by people in the indoor environments where they spend 70 to 90 percent of their time? Studies in developed and developing countries have shown that indoor and outdoor concentrations of most pollutants are often significantly different. Moreover, the local concentrations-both indoor and out-do not correlate well with concentrations measured at the nearest outdoor monitoring site. Thus, to understand the pollutant concentrations to which most people are exposed most of the time, it is necessary to monitor typical indoor environments.

Air Pollutants and Haalth

A pound of pollution released outdoors or in places where people do not spend much time is substantially less damaging to health than the same amount released near people.

For example, the major sources of benzene emissions (a known carcinogen) in the United States are automobiles and industrial plants, now under tightening controls through the Clean Air Act. The major sources of benzene exposure, however, are found indoors in household products and environmental tobacco smoke. Carbon monoxide, long controlled outdoors where it comes mainly from cars, reaches people primarily from gas stoves and by leaking directly into the passenger compartments of cars. Emissions of p-dichlorobenzene, a probable cause of human cancer, come mainly from chemical manufacturing plants. …

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