L.A. Basin Hits Milestone in Cleaning Up Air

The South Coast Air Basin, long the nation’s smog capital, has reached a major milestone in the cleanup of its nagging air pollution problem, meeting the federal standard for nitrogen dioxide for the first time, air quality regulators said Friday.

The region--which includes Los Angeles, Orange and Riverside counties and the non-desert portions of San Bernardino County--has been the only area in the nation violating federal health standards for the brownish-orange gas, which is a major component of ozone, cuts visibility and worsens respiratory illnesses, particularly in children.

Although the area has come increasingly closer to meeting nitrogen dioxide standards for the past several years, stubborn pockets of the pollutant in Pomona knocked the basin out of compliance until 1992. Downtown Los Angeles, Burbank and Anaheim also have had elevated levels.

“While still preliminary, this appears to be another milestone on the path to clean air,” James M. Lents, executive officer of the South Coast Air Quality Management District said in a written statement. “Southland residents continue to enjoy reductions in virtually all types of air pollutants.”

The AQMD also said Friday that levels of carbon monoxide in the basin declined for the year, continuing a four-year trend. Carbon monoxide levels exceeded federal health standards on 33 days, compared to 41 days in 1991 and 1990. Carbon monoxide diminishes the bloodstream’s capacity to carry oxygen and can aggravate heart disease.

Although environmentalists applauded the strides made in nitrogen dioxide control, they were cautious Friday about just what the news means for the Los Angeles area’s long-term air quality problems.

“One year of meeting the standards doesn’t necessarily mean that we have air that’s free of nitrogen dioxide pollution,” said Veronica Kun, a Los Angeles-based staff scientist for the Natural Resources Defense Council, a private, nonprofit group. “However, we know nitrogen dioxide to be a prime contributor to ozone. This means that any reduction in nitrogen dioxide also helps to reduce the immense ozone problem.”

Kun noted that good weather and the recession could have contributed to the reduction in nitrogen dioxide, formed during combustion of fossil fuels. The recession, she said, has reduced the activity of the major culprits spewing out the pollutant: automobiles, utility companies, oil refineries and some manufacturers.

In addition, said Joel Schwartz, staff scientist at the Coalition for Clean Air, the area exceeds federal and state health standards for ozone and particulate pollution more than two out of every three days. Nitrogen dioxide contributes to both.

At ground level, ozone is a major component of smog and can cause breathing problems. Particulates are the only pollutant in which there is a direct correlation between elevated levels and elevated death rates.

“In order to achieve healthful levels of those pollutants, we need to reduce nitrogen dioxide by another 80%,” Schwartz said.

Claudia Keith, an AQMD spokeswoman, acknowledges that one year in compliance with federal health standards does not mean that the region has licked its nitrogen dioxide problem.

One reason is that the area with the greatest nitrogen dioxide problem--Pomona--still has high levels of the pollutant, although it does not exceed federal standards. The federal nitrogen dioxide standard is based on the annual average level and is recorded in the basin at 22 monitoring stations.

When the level at any of these stations exceeds 0.0534 parts per million, then the air is deemed unhealthful. Last year, Pomona recorded 0.0507 parts per million, or 95% of the standard.

“It’s a pretty big change,” Keith said. “We’ve been progressively better than (in) the ‘70s. It’s not a fluke. But it’s unknown whether it will happen again this year. We were almost to the federal standard . . . so it’s not a done deal that we’ll meet the federal standard again this year.”

Keith contends that tougher regulations by the AQMD and the California Air Resources Board resulted in the progress in the region’s air quality. The agencies have adopted numerous rules within the last decade to reduce nitrogen oxide--a precursor to nitrogen dioxide--emissions from fuel-burning stationary equipment and from motor vehicles. The tighter emission limits cover such things as autos, power plants and industrial boilers, furnaces, ovens, heaters and kilns.