New State Study Challenges Old Smog Theories

A new state study, with potentially far-reaching public health and economic ramifications, challenges a long-held assumption that has shaped Southern California’s air pollution battle for the past 20 years.

The study by the Air Resources Board suggests that regulators have been acting on flawed data and that smog can be further reduced by a broader strategy that would require tough new controls on motor vehicles and industrial emissions.

A year in the making, the study is emerging at a time when regulators in the next few years will face such volatile issues such as additional smog controls on new motor vehicles, tougher vehicle inspections under the state’s Smog Check program and new emission controls at oil refineries and electricity- generating plants.

Flaws in Data Seen

The study said the underlying assumptions that have guided the enactment of smog control measures have been based on information that was incomplete and unrepresentative of actual conditions, in part because smog chemistry was not fully understood.

Previous studies, the board said, were based on projections and flawed computer models, including an influential study that was based on only two days of smog readings. But the board’s new findings are based on an analysis of actual smog levels recorded in the South Coast Air Basin during the past 18 years.

The study by the Air Resources Board strongly suggests that regulators may have erred in focusing primarily on only one of the two ingredients that unite in sunlight to form ozone--commonly known as smog.

That strategy has been based on the assumption that controls on hydrocarbons--mostly vapors from solvents, paints and unburned fossil fuel such as gasoline--were sufficient to significantly reduce ozone.

There have been far fewer controls on the other ingredient, oxides of nitrogen (NOx)--which are almost entirely the byproducts of combustion, and are found in motor vehicle exhausts and in emissions from the stacks of power plants and oil refinery heaters and boilers.

It has long been known that nitric oxide, the major ingredient in NOx, breaks down ozone. But that beneficial effect of nitric oxide is far less pronounced than was previously believed, the board’s study said.

In addition, there is a growing awareness that NOx also causes acid rain and acid fog, poor visibility, and particulate nitrates that can cause respiratory health problems.

More Controversy Certain

This is of particular interest because the South Coast Air Basin is the only area in the United States that has not yet met the national Clean Air Act standard for nitrogen dioxide (NO2), another byproduct of oxides of nitrogen.

The ARB staff study is stirring widespread interest among researchers, air pollution regulators and industry, and it is certain to renew a longstanding controversy over the best way to reduce ozone because controls on NOx are far more costly and politically difficult.

“My feeling is that’s the most critical finding of the three years I’ve been on the South Coast Air Quality Management District board,” Larry L. Berg said.

The study comes at a time when similar conclusions about the merits of both NOx and hydrocarbon controls have been reached by a panel of experts who recently testified before an ad hoc committee of the South Coast Air Quality Management District board chaired by Berg.

Berg, long an advocate of more controls on NOx emissions, said that, based on the new findings, he will urge the district board next month to consider a series of new NOx control measures, including tougher vehicle inspections under the Smog Check program, support for more stringent NOx limits on new cars, and tighter restrictions on NOx emissions from stationary sources.

‘Some of the Top People’

AQMD assistant executive officer Jim Birakos said he believes that the Berg committee’s recommendations will have great significance. “He (Berg) has gathered some of the top people in the state dealing with NOx emissions. . . . It will make a difference, I think, in programs to be adopted by the board. You can’t ignore that kind of information,” Birakos said. But even with new information demonstrating the benefits of tighter NOx controls, he added, pollution control costs to industry cannot be ignored.

Already, representatives of automobile manufacturers, the oil industry and electrical utilities are gearing for a protracted fight to limit costly new NOx controls.

Edward J. Faeder, manager of environmental operations for Southern California Edison, said NOx controls would cost Edison more than $1 billion. “You’re not talking about a cheap, off-the-shelf technology.”

There is no doubt that the hydrocarbon control strategy has reduced ozone. Earlier this year, for example, the Air Resources Board announced that ozone in the Los Angeles Basin had hit the lowest point in a dozen years, although the basin is not expected to meet federal clean air standards for ozone concentrations until the year 2020.

At the same time, however, researchers increasingly are questioning the relative lack of emphasis on controlling NOx.

Holding the Line

While the South Coast Air Quality Management District has imposed more NOx controls than other air pollution control districts in the state, they have been essentially aimed at holding the line on NOx emissions to meet the federal clean air standard for nitrogen dioxide rather than reducing oxides of nitrogen overall to combat ozone. Additionally, some of those controls will not be fully effective for another two years.

What seemed to cinch the case for emphasizing the hydrocarbon strategy were previous studies which found that reducing NOx emissions--most of which are in the form of nitric oxide (NO)--would actually increase ozone in the most populated areas of the Los Angeles Basin.

That is because NO molecules at first react with existing ozone upon contact and, like little Pac-Men, eat up or “scavenge” the ozone. At some point, however, the NO is converted to nitrogen dioxide (NO2) which, like Dr. Jekyll and Mr. Hyde, then changes character so that it actually generates ozone.

This phenomenon is one reason that ozone levels are lower near the coast despite the high emissions of NO from oil refineries and power plants.

What the new board study suggests is that the geographical zone benefiting from the ozone scavenging by NO is far smaller than previously thought.

The data gathered by the study strongly indicates that when even relatively minimal NOx controls began to take effect, ozone levels were lowered, especially in those areas of the basin with the worst ozone concentrations, such as the San Gabriel Valley. While the NOx controls increased ozone levels along the coast, the elevated concentrations were not nearly as high as previous studies implied.

Indeed, the declines in ozone concentrations in the smoggiest areas were five times greater than the increases in ozone in coastal areas, according to Gary Honcoop, manager of the air board’s air quality analysis section.

The transition zone between more ozone and less ozone extends roughly from the Santa Monica Mountains to the Santa Ana Mountains.

The differences between the new board findings and those of a 1981 study are of special importance to future pollution control measures.

The previous policy, which emphasized controls on hydrocarbons, was in large part based on a study conducted by Systems Applications Inc. for the Western Oil and Gas Assn. That study found little or no reduction in ozone as a result of NOx controls.

“At the time, it was the most definitive study to date. It gave more than just a clue, but a lot of insight to decision makers on which way to go in the control efforts, where the best strategy was to reduce ozone,” said AQMD spokesman Birakos.

Unlike the board’s analysis, the Systems Applications study was based on only two days of smog readings. It also did not take into consideration a nighttime chemical reaction that reduced NO in the atmosphere.

That oversight would significantly change the conclusions, according to Terry McGuire, chief of the board’s technical support division. He added that SAI has since changed its model to take the night time factor into account.

Philip Roth, an independent consultant who at the time worked for SAI and was involved in the 1981 study, called the ARB study “intriguing” and “certainly worthy of discussion and some scientific inquiry.”

Others who have called for additional studies include Bob Harrison, assistant general manager of the Western Oil and Gas Assn.

‘Difference of Opinion’

“I think there’s a definite difference of opinion between the ARB and industry as to the degree that these pollutants interact upon one another and their results,” Harrison said.

Until those studies are complete, those in industry say, there should be no new and costly NOx controls, and some have again raised the specter that NOx controls would serve to increase ozone in the most populated areas of the basin.

“It’s a factor you have to consider,” Jon M. Heuss of General Motors told the ARB. “On balance,” he said, “we’re very concerned that NOx reductions will aggravate an already serious ozone problem.”

This view is shared by Faeder of Southern California Edison. “Their (ARB’s) overall position from what I understand is that, overall, there’s no great increase in ozone. . . . But when you magnify that by populations exposed you get rather dramatic shifts. Small (ozone increases) and very large populations produce fairly significant results.”

Still, the new Air Resources Board report has clearly put industry on the defensive.