In the South Bay, we're smug about smog. While much of the Los Angeles Basin breathes an unhealthful brew of auto exhausts, industrial fumes and other irritants, the South Bay enjoys air that's as clean as any in the country, officials say, thanks to ocean breezes that push our pollution inland.
Most of the time, that is.
On some winter days when conditions are right--or wrong--the same oxides and particulates that we send to Riverside and San Bernardino head westward for a change, pushed by those Santa Ana winds you hear so much about this time of year.
The Santa Anas--strong, hot winds out of the Mojave Desert that occur erratically between September and March--"clean out the eastern part of the basin and push pollutants toward the ocean," said Ron Ketcham, a spokesman for the South Coast Air Quality Management District. Breezes off the ocean can trap that bad air along the coast, he said.
The result is a layer of brownish air that blankets the South Bay and nearby coastal areas, causing respiratory problems and eye irritations in some people, Ketcham and other officials said.
This winter, in fact, the South Bay experienced its "worst wintertime stagnant air condition since at least 1980," Ketcham said. For 5 of the 8 days between Dec. 18 and 25, the South Bay's air was considered unhealthful, he said.
"You had a weak Santa Ana, but along the coast you also had a stagnant air condition with little wind movement," Ketcham said. In addition, a strong high-pressure system over Southern California created an inversion of warm air over cold air that kept the pollutants from rising and dispersing.
The result on those five days were readings on the Pollutant Standards Index of more than 200 for either carbon monoxide or nitrogen dioxide, Ketcham said. A reading above 200 is considered unhealthful for everyone and above 300 is considered hazardous. The worst days were Dec. 24 (PSI of 240 for carbon monoxide) and Dec. 25 (227 PSI for nitrogen dioxide). It was "a murky Christmas," Ketcham said.
(By comparison, he said, the South Bay can expect readings below 40 on a typical day. Last Sunday, for example, the PSI for carbon monoxide was only 11.)
Several other areas near the coast had higher-than-normal pollution readings during that late December period, Ketcham said, but they extended no farther east than the South San Gabriel Valley.
Luckily, the strong high-pressure systems that cause such protracted problems occur only about once every four years, Ketcham said.
"Usually the coastline has the best air in the basin because of the ocean breezes, but with Santa Anas, Riverside and San Bernardino are clear and you get it."
The bad air at such times extends from Huntington Beach to Malibu for about 10 miles inland, Ketcham said. In a reverse of the usual trend, the severity of the pollution decreases as one moves away from the coast.
The main winter pollutants are nitrogen dioxide, which comes from cars and industrial boilers, and carbon monoxide, also produced by cars. In the summertime, the yellowish-brown nitrogen dioxide interacts with sunlight to become ozone, which can irritate the lungs but is invisible. In winter, however, the sun is too weak to make the conversion, leaving a layer of visibly brown air.
"There's definitely a change" when the Santa Anas blow, said Nan Evans, assistant executive director of the American Lung Assn.'s Long Beach office. Normally, she said, "when you look east in the morning, you see a brown haze. On Santa Ana days, you see the haze in the west. It's very visible from Long Beach."
"I think people in Torrance and your area--because your air is so good most of the time--are more affected," she said, although the lung association has not received any complaints about bad air from the South Bay lately.
The fog that is common to coastal areas this time of year only aggravates respiratory problems, said Gladys Meade, environmental health director for the American Lung Assn. of California and a former Air Quality Management District board member.
"People who have a sensitivity to air pollution or have lung problems or heart problems will find breathing more difficult when the air is saturated with moisture," Meade said. Fog and pollution combined make for an "awful time breathing," she said.
Fog and pollution also make for "acid fog," a corrosive mist that occurs when air is stagnant and laden with nitrogen oxide. Again, coastal areas are most affected by acid fog, which irritates mucous membranes and lungs and can even damage car finishes.
Meade, who lives near the ocean in the Hollywood Riviera section of Torrance, recommends that people who are sensitive to pollution stay inside on bad days and run air conditioners if their units are equipped with charcoal filters. Joggers and other athletes are advised to check on current air conditions by calling the district's 24-hour phone line, 1-800-242-4022.
This occasional wintertime pollution should not cloud the larger picture, Ketcham said.
"For 300 to 320 days of the year you have good air quality," he said, "in terms of anywhere in the country, not just this area." In a typical year, he said, the South Bay has no more than 10 days when the air is considered unhealthful for everyone.
Of course, he said, the quality of the air you breathe "depends on where you are living." People who live near a refinery or power plant or other industrial complexes usually have more polluted air than people who don't, he said. The air next to freeways and other arteries is generally more polluted than the air only a block away.
Time of day is also a factor. Carbon dioxide levels are usually highest in the morning and late evening during the winter. Ozone, the main summer pollutant, is usually highest in the afternoon, but it's not a serious problem in the South Bay.
Most of the time, that is.