S.D. Spared as Dense Smog Stifles L.A. : Weather: It’s been a scorcher in San Diego, too, but the county has escaped most of the smog that has choked residents of the Los Angeles Basin.

The Los Angeles area this week has been plunged into a merciless plague of heat and smog that has obliterated skylines, sending a few disgruntled tourists packing for home and leaving some residents literally gasping for clean air.

First-stage smog alerts have been posted in parts of the San Gabriel and San Fernando valleys for five of the past seven days. In downtown Los Angeles, visibility has been limited to a few miles, with the San Gabriel Mountains lost in a sea of brown haze.

The foul air was just as foul Wednesday, with “unhealthful” air in 12 of the 34 air-monitoring areas of the South Coast Air Quality Management District, including normally clear West Los Angeles.

San Diego County was at the center of the high-pressure system responsible for the Southern California heat wave, but the county largely was spared from the smog, officials said Wednesday.

The highest pollution reading all week was Alpine’s level of 125 on Wednesday, right in the middle of the standard pollution index range considered “unhealthful.”

By comparison, air pollution levels in the Los Angeles area have been above 200.

On Tuesday, El Cajon was the only area in San Diego County to reach 100 on the pollution scale, said Bob Goggin, public information spokesman for the San Diego County Air Pollution Control District. Between 51 and 100 is considered “moderate.”

Other readings Wednesday included 84 at Escondido, 75 at Kearney Mesa and 50 downtown.

The only other readings at the unhealthful level over the last week were at Alpine on Sept. 8, in El Cajon on Sept. 9.

But throughout the Los Angeles area, playground games have been canceled and pedestrians have protected themselves from the unrelenting sun and contaminated air with parasols and wet handkerchiefs. Those who could avoided the smog altogether by staying indoors.

The Los Angeles Civic Center posted a high of 94 degrees, the ninth consecutive day of plus-90 degree weather. The inland valleys fared even worse, with highs reaching 105 in Riverside and Ontario.

Jim Lewis’ work as a garbage-truck driver took him to what was arguably the most unpleasant place to be on a hot, smoggy day--high atop 500 feet of trash at the Sunshine Canyon Landfill.

As a light wind kicked up a cloud of dust amid the sea of disposable diapers and plastic trash bags, Lewis watched bulldozers cover his load of garbage with a layer of dirt.

“They keep the trash covered up pretty good, so you don’t have too much stench,” said Lewis, 56. “It’s the smog and the fumes from all these trucks that bothers me. . . . The heat isn’t that bad. It’s nothing like what the fellas are suffering in Saudi Arabia.”

What’s causing the hellish weather? Joe Cassmassi, a weatherman with the AQMD described the conditions in the atmosphere above Los Angeles as “worst-case meteorology.”

Normally, temperatures near the century mark break up the inversion layer that holds pollutants close to the ground. But this week, a high-pressure system centered over San Diego has kept the inversion layer intact, leading to the unusual combination of smog and near-100-degree heat.

Even the usually pleasant beach communities have been affected by the smog siege, Cassmassi said. “You have to get out of L.A. pretty much, and even out of Orange County to get away from the smog.”

For those out-of-towners visiting the Los Angeles area, Wednesday’s dirty air and heat seemed a far cry from the pleasant, post-card vistas they had seen in the travel agent’s office back home.

Karen Steven, a 21-year-old tourist from Scotland, sat in the shade of a kiosk at the front entrance to the Huntington Library in San Marino, resting after a midday walk that unexpectedly became a desert-like trek.

“It’s almost unbearable,” she said. “I expected brilliant sunshine and clear skies. It’s been kind of a surprise.”

Joe Prigatamo, a volunteer who collects donations for the library, offered the weary tourist a glass of water. It wasn’t the first time Prigatamo had rescued a pedestrian from the heat wave.

Earlier in the day, a woman and her child approached Prigatamo’s kiosk on foot. The woman said she was from Switzerland.

“I told her, ‘You walked all the way from Switzerland in this heat, that’s crazy,’ ” Prigatamo said, laughing. “But seriously,” he added, “another person walked from the Norton Simon Museum (in Pasadena). Now that’s a long way.”

Some Los Angelenos appeared to be taking it all in stride, greeting the the perennial summer-ending smog siege an heat wave with the same aplomb reserved for rush-hour traffic jams.

Daniel Urquisa, 29, spent Wednesday installing a sprinkler system at Cal Tech. After three days of working shirtless in the hot sun, his skin was burnt bright red. But he didn’t seem to mind.

“It’s like been to the beach,” he said in Spanish. “Sure you can feel the heat. But you get used to it.”

Times staff writer Linda Roach Monroe contributed to this report.