Dirty Air Getting Cleaner, Data Say
The murky brown cloud that masquerades as the sky over greater Los Angeles has a small, silver lining.
The air is getting cleaner, according to years of data from monitoring stations, including those in the San Fernando, Santa Clarita and Antelope valleys and eastern Ventura County.
Progress has slowed since the 1970s and early ‘80s, when auto emission controls and limits on industrial pollution brought immediate gains. Still, according to air quality officials, the air is improving and the trend will continue into the 1990s, thanks to controls on industrial and vehicle emissions that are already on the books.
But there’s a long way to go. Of about 80 urban areas that violate the federal health standard for ozone, the main ingredient of smog, Los Angeles has the highest levels of the lung-irritating gas, and Ventura County is near the top of the list.
Short of Standards
Existing controls will leave the area far short of meeting the ozone standard. Neither will they be enough to bring the South Coast air basin--which includes parts of Los Angeles, Orange, Riverside and San Bernardino counties--into compliance with federal carbon monoxide, particulate and nitrogen dioxide standards. Limits on these pollutants are being met in all areas of Ventura County.
There are also stronger state standards, which are academic in the South Coast basin, where the weaker federal limits are not met.
But more disturbing, unless present controls are toughened, the clean-air trend will bottom out by the mid-1990s in Ventura County and by the year 2000 in the South Coast basin, air quality officials say. After that, pollution levels will rise again and wipe out previous gains. The San Fernando and Santa Clarita valleys would not bear the brunt of this fouler air. Hardest hit would be the San Gabriel Valley and areas to the east, where prevailing winds deliver Los Angeles’ pollution and where most growth is predicted.
Air Quality Trends
As air quality trends in the San Fernando Valley and neighboring areas clearly show, present pollution control rules are approaching a point of diminishing returns, said Margaret Hoggan, head of the air quality evaluation section of the South Coast Air Quality Management District. Most older, dirtier cars have already been replaced by newer, cleaner ones. And most cuts in industrial emissions required by existing rules have already occurred.
Meanwhile, rapid population growth will continue, bringing more cars and other pollution sources. This growth “tends to subvert all the control measures that we adopt,” Hoggan said.
It’s the same in Ventura County, said Bill Mount, air quality planning manager for the Ventura County Air Pollution Control District. Ozone levels have continued to fall despite a 22% population increase over the past decade, Mount said, but “the improvements that we’re seeing are not as dramatic as in past years.”
“Obviously we have to do more” or “people are going to continue to breathe unhealthful air, and there will continue to be health effects from that,” Mount said.
Yet there “are no silver bullets out there anymore,” he said. “It’s going to be a tough, tough fight.”
Some help is on the way from Sacramento in the form of a strengthened vehicle smog check program. Moreover, the state Air Resources Board in June imposed tougher tailpipe emission standards on new cars and pickup trucks, beginning with the 1993 model year. The rules are expected to cut carbon monoxide emissions from new cars by 50% and ozone-forming hydrocarbons by 30% by 1997, although some air quality officials complained that the rules are too long in taking effect.
And the South Coast district in March adopted a sweeping plan to meet air quality standards within 20 years through 120 separate control measures expected to be passed in coming years. These include new curbs on power plants, oil refineries and other polluting industries, conversion of part of the area’s car and bus fleet to alternative fuels, and reformulation of various industrial and household products--including paints, solvents and deodorants--to reduce ozone-forming vapors.
While existing controls involve technological fixes, the new plan could impose costs and life-style changes on ordinary citizens. For example, special parking charges would be imposed on those who drive alone to work.
Under pressure from the U. S. Environmental Protection Agency and a lawsuit by Citizens to Preserve the Ojai, an environmental group, the Ventura County district is also formulating a strategy for meeting the ozone standard, the only one it does not now meet. South Coast officials are predicting attainment of the ozone standard in 2007; Ventura County hasn’t projected an attainment date.
Camarillo is best,
Santa Clarita worst
Except for Simi Valley, smog capital of Ventura County, the county’s ozone problem is considerably milder than that of the San Fernando Valley and the valleys north of it.
In 1988, a high smog year because of unfavorable weather, the federal ozone standard was violated on 52 days in Simi Valley. This means that on 52 days, ozone levels exceeded an hourly average of 0.12 parts per million and the air was deemed “unhealthful.”
Things were a lot worse in Santa Clarita, where the standard was exceeded on 107 days. But even Santa Clarita’s air, though far from the best for ozone, is also not the worst. For example, Santa Clarita breathed easier last year than Glendora, where the ozone standard was exceeded on 148 days. That’s a huge number, considering that the high ozone season lasts only half the year, during the months of intense sunshine and weak winds.
In the stratosphere, ozone filters the sun’s harmful ultraviolet rays, but on Earth it is a colorless gas that at high levels can cause shortness of breath, reduced resistance to infection and impaired athletic performance.
Ozone is formed when hydrocarbon vapors from tailpipes, industrial operations, and paints and chemicals mix in strong sunlight with oxides of nitrogen, another type of pollutant emitted by vehicles and industry.
Ozone levels are regularly measured by the South Coast district at 37 monitoring stations, including those at Burbank, Reseda, Santa Clarita and Lancaster. The Ventura County district maintains six, including stations at Simi Valley, Thousand Oaks, Piru and El Rio near Camarillo.
Yearly variations in weather can mask long-term trends, as was shown last year when unusual weather conditions, rather than increased emissions, produced some of the worst ozone levels of the 1980s. But from data averaged over several years, long-term trends at the eight area stations emerge.
Data show that of these eight stations, El Rio has the lowest ozone levels, followed by Piru and Thousand Oaks. Santa Clarita tops the list of smog-bound areas, mainly because of pollutants drifting north from Los Angeles and cooking in the sun. Burbank and Reseda are close behind in the frequency of ozone violations. Simi Valley and Lancaster are somewhere in the middle.
But there’s been progress everywhere.
For example, Santa Clarita exceeded the federal ozone standard by an average of 124 days per year from 1976-78. But the average dropped to 88 days per year from 1983-85 and 87 days from 1986-88.
During the same period, ozone violations in Burbank fell 27% from an average of 105 days per year from 1976-78 to 85 days in 1983-85 and 78 days in 1986-88.
Ozone violations at Reseda dropped 35% from 105 days per year from 1976-78 to 73 days from 1983-85 and 68 days from 1986-88.
At two of the eight monitoring stations--Simi Valley and Lancaster--the trend was not so clear. At Simi Valley, ozone violations plunged from 76 days per year in 1976-78 to 39 days in 1983-85, but then rose to 41 in the last three years. At Lancaster, where there were 32 ozone violations per year from 1976-78, the number climbed to 50 per year in 1983-85 before dipping to 41.
By another measure, however--the frequency of the smoggiest days, when ozone is at alert or “episode” levels--the situation seemed markedly better. A stage-one episode occurs when ozone reaches an hourly average concentration of 0.20 p.p.m., and air is deemed “very unhealthful.”
Such ozone peaks fell sharply, from an average of 47 episode days per year in the Santa Clarita Valley from 1976-78, to 17 days from 1983-85 and 15 during the last three years.
Ozone episodes in Reseda fell from 29 per year from 1976-78 to nine and four, respectively, during the last two three-year periods.
In Simi Valley, there were four ozone episodes per year from 1976-78, but only one per year in 1983-85 and none from 1986-88.
And in Lancaster, stage-one episodes fell from two per year during the first three years to zero in the next two three-year periods.
Worst of the Rest
The South Coast air basin also fails to meet federal standards for nitrogen dioxide, carbon monoxide and particulates, with violations of the last two standards occurring in the San Fernando Valley.
Carbon monoxide, or CO--95% of it from vehicle exhaust--is a poison gas that interferes with the transport of oxygen through the body. Fetuses and infants may be particularly susceptible to high CO levels, along with people with heart problems or anemia.
In contrast to ozone, carbon monoxide levels are highest in winter, when temperature inversions trap auto exhaust near the ground.
Carbon monoxide levels have dropped dramatically in the South Coast basin, thanks to tailpipe emission standards. Whereas the federal CO standard of 9.4 p.p.m., averaged over eight hours, was exceeded at one or more monitoring stations 33% of the days from 1976-78, the rate dipped to 14% of the days from 1986-88. Still, the air district has predicted that the CO standard won’t be met throughout the basin until the end of ’97.
Burbank remains one of the areas of most frequent violations because of heavy freeway traffic and stagnant air.
Carbon monoxide violations have become less routine in Burbank over the last decade, although the rate of improvement has slowed considerably in the most recent years.
Burbank violated the CO standard an average of 76 days a year from 1976-78, 16 times per year from 1983-85 and 13 times from 1986-88.
Carbon monoxide violations in Reseda over the same periods dropped from 47 days per year to 11 and then five.
Lancaster averaged slightly more than one CO violation per year from 1976-78 but had zero violations during the last two three-year periods.
After Santa Clarita recorded only two CO violations from 1976-78, South Coast officials stopped monitoring CO there. Their modeling showed that CO levels would stay below the standard as new cars with emission controls replaced old ones.
But Santa Clarita officials, seeking reassurance, persuaded the air district to resume CO monitoring this year. With a mobile monitoring station also posted in the area by the state Air Resources Board, Santa Clarita will be awash in air-quality data.
Because of rapid growth in the Santa Clarita Valley and Lancaster-Palmdale to the north, “we’ve got traffic sitting on” the Antelope Valley Freeway, said Santa Clarita Mayor Jan Heidt. “We never really knew what our air quality was here, and yet we had people here who suffered,” she said.
Attainment of the federal particulate standard will not occur until 2007, the same year the ozone standard will be met, South Coast officials predict.
These airborne particles, mainly road dust and soot from vehicle exhaust, are called “PM 10" because the rule applies to particles less than 10 microns in size, which are small enough to be drawn deep into the lungs. PM 10 can impair breathing. And since PM 10 includes carcinogenic soot from vehicle exhaust, experts say it may cause some of the lung cancers not attributable to smoking.
Although the murky haze of Los Angeles’ skies is sometimes assumed to be because of ozone, the main ingredient of smog, it is really particulate matter, tinged with brownish nitrogen dioxide, that cuts visibility.
Worst PM 10
The worst PM 10 levels, measured at Rubidoux in Riverside County, are nearly twice the federal standard of 50 micrograms per cubic meter, averaged over a year. PM 10 monitoring began only in 1985 and has not been done at most of the district’s monitoring stations. For example, the first PM 10 data for Santa Clarita and Lancaster are being gathered this year.
But of stations that have measured PM 10, Burbank has had some of the higher levels. Burbank’s PM 10 average last year of 62 micrograms exceeded the federal standard by 24%.
The South Coast basin has the dubious distinction of being the only area in the country violating the federal standard for nitrogen dioxide. A lung irritant emitted by vehicles and fuel-burning equipment such as industrial boilers, power plants and home water heaters, nitrogen dioxide is one of the oxides of nitrogen that blends with hydrocarbons to form ozone.
The federal nitrogen dioxide limit, 0.0534 p.p.m. as an annual average, is exceeded mainly in central Los Angeles. But Burbank comes close, with an average concentration in 1988 of 0.0528 p.p.m. In 1988, average nitrogen dioxide concentrations in Reseda and Lancaster were 0.0378 p.p.m. and 0.0162 p.p.m., respectively.
South Coast air district officials predict that the nitrogen dioxide standard will be attained throughout the district by the end of 1996.
First number is average number of days per year when ozone levels exceeded federal health standard of 0.12 parts per million, based on an hourly average. Air is considered “unhealthful"on such days. Second number in bold is average number of days per year of “Stage 1" ozone episodes. A Stage 1 episode occurs when ozone concentrations reach 0.20 p.p.m., air deemed “very unhealthful.”
Monitoring Station 1976-'78 1983-'85 1986-'88 Burbank 105/28 85/19 78/8 Reseda 105/29 73/9 68/4 Santa Clarita 124/47 88/17 87/15 Lancaster 32/2 50/0 41/0 Simi Valley 76/4 39/1 41/0 Thousand Oaks 38*/1 9/0 8/0 Piru N.D./1 9/0 7/0 Camarillo/El Rio 13*/1 4/0 4/0
* Figure is average for 1976-77. Data for 1978 incomplete.
N.D: No Data
Figures are average number of days per year when the carbon monoxide levels exceeded federal standard of 9.4 p.p.m. averaged over an eight-hour period. All Ventura County sites are in compliance with the federal standard, according to Ventura County Air Pollution Control District. Therefore, no regular monitoring is done.
Monitoring Station 1976-'78 1983-'85 1986-'88 Burbank 76 16 13 Reseda 47 11 5 Santa Clarita 0.7 * * Lancaster 1.3 0 0
* Not measured
Sources: South Coast Air Quality Management District, Ventura County Air Pollution Control District