Regulators Shift Focus to Tiny Air Pollutants

It sounds like a recipe for some sort of noxious stew: Take soot from trucks and buses, add a bit of ammonia from dairy farms, mix in nitrates from car exhaust, a hefty dose of dust and dirt that blow off streets and construction sites, a sprinkling of ash from fires, some sulfur from factories and a final dash of sea salts.

Combined, this brew can clog the filters at an air-quality monitoring station in Rubidoux, on the outskirts of Riverside, within a span of hours, rendering them opaque with fine black particles that also can lodge in the lungs of people who live there.

Occasionally, most recently on a dismal day in January, the mass of airborne particles that shrouds the Rubidoux area reaches three to four times greater than a health standard set by state authorities. While the Inland Empire suffers the most severe and frequent bouts, unhealthful amounts of these particles occur year-round throughout the four-county Los Angeles Basin.

Beginning next year, the Southland’s air quality agency will embark on a new frontier as it launches a decade-long quest to control this pervasive and mysterious pollutant known as PM 10--particulate matter smaller than 10 microns, one-fifth the width of a human hair.

After decades of obsessing on ozone, the Los Angeles region’s most notorious air pollutant, the South Coast Air Quality Management District and the California Air Resources Board are shifting their focus toward designing a strategy by 1997 to clean up these microscopic particles.

“Over the next three or four years, I fully expect we’ll see a shift in emphasis in California,” said Mike Scheible, the state board’s deputy executive officer. “PM 10 will become the air pollution topic for the end of this century and the beginning of the next century. It is an especially dangerous air pollutant.”

Under federal law, the Los Angeles Basin--which is twice as polluted with particulates as most areas in the nation--has until Feb. 8, 1997, to detail how it intends to achieve national PM 10 health standards by 2006.

Health researchers have called the ultra-fine particles California’s deadliest air pollutant because they can escape the body’s defense mechanisms and penetrate deep into the lungs. PM 10 has been linked in recent scientific studies to chronic respiratory disease and premature deaths from heart attacks, pneumonia, asthma and other ailments. A gritty fog of PM 10 sometimes reduces visibility to a few blocks around Ontario and Riverside and to a mile in eastern Los Angeles and northern Orange counties.

“Particulates have taken a back seat to ozone control in a lot of areas,” said Ron White, environmental health director at the American Lung Assn. “But the health data that has emerged in the past two years has been a real wake-up call. Unfortunately, a lot of areas in the country--including the Los Angeles Basin, even though it is further ahead than most--are playing catch-up to develop a package of control programs.”

As they chart their new course, state and local air officials face some wrenching decisions on how to spread the cleanup burden, which will probably cost billions of dollars per year, among the various sources of PM 10.

Virtually every human activity that burns fuel, stirs up dirt or dust, builds a structure or tills soil creates a cloud of atmospheric particles. The PM 10 that obscures the region’s skies is a mystifying blend of man-made and natural substances, its contents shifting from city to city and season to season.

Because it is such a grab bag of pollutants, PM 10 poses one of the most profound challenges facing the two air agencies. The AQMD, as it tries to hash out an equitable cleanup plan, is admittedly reliant on imprecise and unsophisticated data on the degree of blame to assign each source.

“There are some tough questions ahead of us and so many unknowns about the composition of PM 10,” said Norton Younglove, who recently retired as a Riverside County supervisor and AQMD board member and will chair a PM 10 working group representing the various industries, municipalities and regulators. “Depending on how the data shakes out, we may have to kick at each other a bit.”

The planning process got off to a contentious start in August when Los Angeles Mayor Richard Riordan proposed a major change in the AQMD’s 20-year anti-smog plan that pitted the cities near the coast against the region’s more inland areas.

The mayor suggested that it may be more cost-effective for the air district to target particles from outlying dirt roads and dairy farms than to mandate alternative fuels for urban trucks, trains, ships and other diesel equipment. Citing possible economic disruption, he asked the AQMD to remove the proposals aimed at particulates from its plan.

Many Inland Empire officials reacted angrily, accusing Los Angeles of trying to shift the PM 10 burden to them.

Now the state and local air boards trying to solve the PM 10 problem are wrestling with the very question posed by Riordan and his staff: Should they assign the highest priority to “fugitive dust”--particles of earth from roads, construction sites and fields--or to exhaust from motor vehicles? That debate, in essence, pits Chino’s farms against Los Angeles’ trucks.

“It’s easier for those upwind to ignore this (PM 10) problem, but we can’t help but take it more personally here because we are impacted the most,” said Younglove, a longtime Riverside County resident. “Politically, it is unquestionably easier to pick on cows--which are phasing out anyway--and rural roads than ships, planes and trains, which are large, important parts of our economy.”

About 115 million people in the United States, including one-third of California’s population, live in areas where the air violates federal PM 10 health standards set in 1987, according to U.S. Environmental Protection Agency data. The record is far worse for a more stringent state health standard; just one area of California, Lake County, east of Mendocino, complies. However, only the severely polluted areas in California, those that violate the federal standard, face the 1997 deadline for devising a cleanup plan.

In the Los Angeles Basin, violations of the PM 10 health standards occur under an enormous variety of weather conditions, from stagnant summer days to gusty fall winds.

“Really, the only time of year that we are free of higher levels of PM 10 is during the rainy season--most of January, March and the beginning of April,” said AQMD senior meteorologist Joe Cassmassi.

As dismal as the record is, research over the past year indicates that the national standard may be too lax to protect public health. In a study of 8,000 people in six cities, the Harvard School of Public Health reported last year that PM 10 increases the risk of early death 26% and shortens lives one to two years in moderately polluted cities--such as Steubenville, Ohio--which already comply with the federal standard. Other research shows that respiratory deaths increase 3.4% and asthma attacks increase 3% for every small increase (10 micrograms) in PM 10.

Still, of all the major air pollutants, particulates remain the most poorly understood.

Even basic assumptions--what is it comprised of and which are the biggest sources--are based on imperfect and outdated databases and models. AQMD measurements that define its composition are almost a decade old.

To resolve some of these uncertainties, the AQMD board recently authorized $600,000 for a 1 1/2-year research project to decipher the chemical makeup of the smallest, most hazardous particles and the role of motor vehicles and ammonia. The agency also is seeking $1.5 million in research funds from other groups, including the city of Los Angeles and the oil, auto, construction and dairy industries.

PM 10 remains such an enigma because it is the only major pollutant that is not identified by its chemical contents. Instead, it is crudely defined purely by its size. An airborne particle of anything trapped in a 10-micron filter--mineral, metal, soot, soil or synthetic material--qualifies as the pollutant.

Unlike Palm Springs, which suffers major dust storms, the vast majority of PM 10 in the Los Angeles Basin comes from man-made sources, with only a slight fraction coming from minerals blowing from the land or ocean, said John Watson, a research professor at the University of Nevada-Reno’s Desert Research Institute who studies particulates throughout the West.

Each day in the basin, about 850 tons of particulates under 10 microns pollute the air from streets, farms, trucks, buses, cars, oil refineries, mines and other sources, according to an AQMD inventory. Also, about 1,000 tons per day of nitrogen oxides, mostly from motor vehicles, and 200 tons of sulfur from industrial plants can react in the atmosphere to indirectly create particulates.

About one-third of the basin’s PM 10 is ammonium nitrate, a blend of nitrogen from vehicles and ammonia released in the air largely from dairy farms.

“It is a very complex pollutant,” said White of the lung association. “Not only do you have to worry about direct emissions, but also the secondary sources (from) gases, typically from industrial sources and cars, that get transformed in the atmosphere into particles.”

One of the most challenging mysteries is the source and volume of dust that blows from roads and fields. On some nights in Riverside, calcium particles cause dramatic peaks in PM 10, but no one knows where they come from. Watson believes that some type of human activity is stirring up calcium-rich soils.

“The data on fugitive dust are very, very inaccurate and probably overestimated,” Watson said. “It’s very difficult to trace it back to their sources.”

By volume, the single largest culprit is dust and dirt stirred up on paved roads, which are responsible for 450 tons per day of PM 10. But the tinier the particle, the more serious the health threat, so the AQMD and state board are likely to focus their regulations on particles measuring under 2.5 microns, which come predominantly from trucks and cars, rather than the larger particles blowing off dirty roads.

None of the sources of PM 10 presents an easy or cheap solution.

Controlling dust from roads and fields could require more thorough and frequent street sweeping, enclosures for manure and other waste piles, wind screens, planting of vegetation and slowing of traffic through dusty areas. Eliminating substantial amounts of particles from trucks, buses and other diesel-powered vehicles means switching to alternative fuels such as natural gas and methanol.

“In Los Angeles, the easy stuff has already been done,” Watson said. “You can’t just nail some power plant. You’ve already cranked down as far as you can on many of these sources.”

Also, the state may have no choice but to focus on motor vehicles because the federal Environmental Protection Agency is leaning toward imposing a new standard for tinier particles. The agency is under court order to review its PM 10 standards by Jan. 31, 1997--eight days before local cleanup plans are due.

Trucking companies vehemently oppose standards that would end use of diesel--which is a cheap and efficient, but dirty, fuel.

Today’s diesel trucks contain particulate-trapping filters mandated by state emission standards. Compared to trucks manufactured in 1970, 1994 trucks are 80% to 90% cleaner in particulates and 65% to 70% cleaner in nitrogen oxides.

“Diesel technology has already come a long ways,” said John Fischer of Detroit Diesel, a major manufacturer of truck and bus engines.

In its ozone cleanup plan adopted last month, the state ARB proposed a standard that by 2002 would cut in half nitrogen oxides from new California-based heavy-duty trucks. The state plan also lists a future option of halving the limit again after 2004--which would require new catalytic technology or switching to an alternative fuel.

Stephanie Williams, a California Trucking Assn. vice president, said fuels such as natural gas might be an option for short hauls within the region, but not trips longer than 250 miles, in which heavy-duty trucks must climb mountain passes.

“Unfortunately,” Fischer said, “with any alternative fuel, you lose one of the major advantages you have with diesel--its fuel efficiency.”

Ammonia is also a mystery, although most fingers point to piles of cow manure at Chino’s dairy farms. Dairy farmers, struggling with water quality regulations and dropping profits, worry that tough new PM 10 rules will target them.

Jack Broadbent, the AQMD’s planning director, said the lack of understanding about the role of each type of particle poses a “significant impediment” as his agency plans its attack on the pollution.

“There needs to be a great deal of work in reducing the great number of uncertainties,” he said. “We have a very open mind (about control techniques) at this point.”

Yet air quality officials do not have much time to seek the answers before the 1997 deadline.

“The big question of concern,” Younglove said, “is whether we can collect this data quick enough to meet federal deadlines.”

In the face of politically influential opposition, White said the AQMD and state air board need political will if the Los Angeles region is to meet its mandate.

“If the promises are kept, I think 2006 is achievable,” he said. “But it’s a question of whether those commitments will be met and maintained.”

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Where It Comes From

On an average day, more than 800 tons of PM 10--particles less than 10 microns in size--are emitted into the air of the four-county Los Angeles Basin. The following list shows the amounts from direct sources of particles; abundant gases such as nitrogen, ammonia and sulfur which indirectly form particles in the atmosphere are not included. Source: Amount per day Paved road dust: 449 tons Unpaved road dust: 137 tons Construction: 103 tons Industrial: 47 tons Trucks: 36 tons Cars: 24 tons Other mobile sources: 23 tons Farms: 22 tons Dust and fires: 11 tons ***

SHIFTING THE BLAME

The source of PM 10 varies from place to place, prompting a battle among cities and industries over what should be regulated.

In the Riverside County area of Rubidoux, which suffers the most severe PM 10 pollution, a large percentage comes from road dust and dairy farms.

Downtown Los Angeles, however, gets more from motor vehicles. The smallest and most dangerous particles, under 2.5 microns in size, nearly all come from trucks, cars and industries that burn fuel.

RUBIDOUX IN RIVERSIDE COUNTY * Fugitive dust (From roads and fields): 42.1% * Ammonium nitrate (Ammonia from dairy farms and sewage, and nitrates from cars): 25.4% * Limestone: 7.9% * Motor vehicles: 7.7% * Secondary carbon (Carbon-based particles that form from petroleum vapors): 7.0% * Ammonium sulfate (Mix of ammonia from dairy farms and sewage and sulfur from industrial plants): 6.9% * Marine (Sea salts): 2.2% * Residual oil (Power plants that burn fuel oil): 0.8% *** DOWNTOWN LOS ANGELES * Fugutive dust: 38.6% * Ammonium nitrate: 18.8% * Secondary carbon: 13.1% * Motor vehicles: 11.5% * Ammonium sulfate: 11.3% * Marine: 4.5% * Residual oil: 2.2% Sources: South Coast Air Quality Management District: 1994 Projected Emission Inventory in the Draft Air Quality Management Plan, 1994 Particulate Air Quality Technical Report

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Areas at Risk

Microscopic particles in the sky that obscure visibility and lodge in the lungs are the newest focus of air pollution authorities. The map below shows the average concentration of PM 10 particles--so named because they are less than 10 microns in size--in areas of the South Coast air basin for 1992. Areas with an annual average of more than 50 micrograms of PM 10 per cubic meter of air violate federal standards. The state deems more than 30 micrograms unhealthful.

Source: South Coast Air Quality Management District