Tackling smog ozone: tougher than thought.

Tackling smog ozone: Tougher than thought

When president Bush proposed his clean air legislation last month, he focused on pollution-control methods that use currently available technology (SN: 6/17/89, p.375). But a new analysis indicates smog ozone may be more difficult to produce than he and others realized.

This week, the conressional Office of Technology Assessment released a report stating that with existing methods, only half the cities now exceeding the Environmental Protection Agency's ozone standards can achieve a safe smog level by the year 2000. Controlling ozone "will be a real tough job, so we need to start [developing innovative ozone-reduction approaches] today," says Robert M. Friedman, the report's project leader.

Taking a deep breath can prove stressful for many an urbanite on a smoggy afternoon. Ozone-laden air can trigger at least a tinge of chest pain or a cough, especially in people wh are exercising. About half the U.S. population lives in areas where smog ozone exceeds the EPA's safety ceiling of 0.12 parts per million on at least one day of the year (SN: 6/17/89, p. 375).

The need for better smog-control strategies is underscored by new evidence of ozone's lung-damaging potential, presented last month at a meeting of the Air and Waste Management Association in Anaheim, Calif. Researchers from the University of Arizona in Tucson reported that the higher the ozone concentration (which varied between 0.021 and 0.1 parts per million in the Tucson study), the more it depresses a person's respiration rate over a one-day period.

The observed human effects appear reversible, says study leader Michal Krzyzanowski. But another research team at the conference described potentially permanent damage in rats, whose lung membranes thickened after 18 months' exposure to daily smog-ozone levels similar to those a person would breathe in a high-ozone city. The rat's lungs did not return to normal after a four-month recovery period, although a longer breath of fresh air might prove the changes reversible, says study author Gary E. Hatch of the EPA in Research Triangle Park, N.C.

Ozone forms when volatile organic compounds and nitrogen oxides meet in sunlight. Automobile exhaust and evaporated solvents, as well as natural vegetation and other sources, can release the volatile organic compounds. Nitrogen oxides come mainly from fossil-fuel combustion. Past control efforts have focused on human-produced organic hydrocarbons, in part because restricting their production appeared less expensive than controlling nitrogen oxides. But recent scientific evidence indicates that limiting nitrogen oxides may be a more effective approach to reducing smog ozone (SN: 9/17/88, p.180).

The new government report suggests several target areas for smog-ozone strategies:

* Stricter regulatory controls on nitrogen oxide emissions from motor vehicles and electrical and industrial boilers could reduce these pollutants by more than 20 percent in some areas, especially rural ones (SN: 7/8/89, p.22).

* Regulators need to encourage development of new products and processes to reduce the need for ozone-contributing solvents, about half of which can't be controlled with existing methods.

* Alternative motor vehicle fuels such as methanol and compressed natural gas, though costly, might contribute as much as 90 percent less ozone than gas-powered vehicles.

* Cutting automobile use through mandated staggered work hours, incentives for carpools and more efficient public transportation could also substantially lower smog levels.