Living With Smog

The familiar shade of beige that tinges the skies over the San Fernando Valley every summer may be paler than it was 20 years ago, but no less irritating on high- smog- level days. Watery eyes, scratchy throats and headaches are some of the symptoms attributed to the man- made chemical soup.

According to the South Coast Air Quality Management District, which monitors pollution levels, the air is getting cleaner, thanks to tougher controls on autos and industry. But in the coming decade, the AQMD plans to keep closer track of particulate pollutants, the tiny pieces of soot that can lodge deep inside the lungs.

Physicians are also paying attention to dangerous smog levels. They are seeing patients with preexisting respiratory ailments worsened by pollution, as well as healthy people with pollution- caused symptoms. Ozone is responsible for up to 10% of respiratory hospitalizations in Los Angeles, according to a study released last week. Dr. Henry Gong, a USC medical professor and chief of Environmental Health Services at Rancho Los Amigos Medical Center in Downey, has carried out a number of studies on urban air pollution. Gong calls smog’s ozone and carbon monoxide “silent killers” because they decrease breathing reserves and make people more susceptible to lung infections. The long- term effects of breathing pollutants have yet to be determined, but there is some evidence that long- term exposure can cause premature aging of the lungs.

Physical Effects

Pollutants in the air we breathe can cause physical symptoms in healthy people, as well as aggravate preexisting respiratory conditions.

1. Lungs: Difficulty breathing; lungs and airways can become swollen and restricted. Decreased breathing reserve and increased susceptibility to lung infections.

2. Throat: Fibers along the respiratory tract become irritated, causing sore throats and coughing.

3. Eyes: Irritation, causing stinging and tearing.

4. Head: Headaches.

5. Stomach: Nausea.

Carbon Monoxide’s Effects

This chemical works its way into lungs without irritation, but from there it enters the bloodstream and is reluctant to leave.

Once in the bloodstream, its binds tightly with hemoglobin in the blood, which normally carries oxygen. The more carbon monoxide carried by blood, the less oxygen is available to feed the body, resulting in reduced performance and endurance.

Smog Stew

The Los Angeles Basin, particularly the valleys, acts as an oven, cooking pollutants on hot, sunny days. Chemicals emitted from vehicles and industry react with sunlight, and still air holds the pollutants close to the ground. Surrounding mountains act as a barrier, concentrating smog close to valley floors.

* Ozone: Smog’s main ingredient, a potent invisible gas formed from hydrocarbons and nitrogen oxides from petroleum products such as emissions from vehicles and industrial plants, and solvents in paints.

* Particulates: Microscopic grains of diesel exhaust, smoke from aircraft, soot, dust and sea salt.

* Carbon monoxide: Emitted by idling vehicles. More of a problem in winter, when drivers warm up their cars in cool weather.

Pollution Levels

Southern California pollution levels are improving every year, according to the AQMD, Ozone- forming pollutants have dropped up to 30% since the mid- 1980s, due in part to new pollution controls on vehicles and industry.

*

Days over Federal Standard

In the last decade, the Valley has experienced a decline in the number of days over the federal ozone minimum standard of .12 parts per million. One reason for the large decline a few years ago, according to the AQMD, could be wind patterns caused by the Catalina eddy effect, which distributes pollution over a more widespread area.

*

Stage 1 Alerts

First- stage smog alerts in the Los Angeles basin declined 43% in 1995 from the previous year. During such an alert, the air is deemed unhealthful for everyone to breathe and even healthy adults and children are advised to avoid outdoor activity.

*

1985: 83

1986: 79

1987: 66

1988: 77

1989: 54

1990: 41

1991: 47

1992: 41

1993: 24

1994: 23

1995: 13

Sources: South Coast Air Quality Management District, Dr. Henry Gong; Researched by JULIE SHEER / Los Angeles Times