Air Quality Nearly Hits Stage 1

Although it was hard to tell by looking at the clear skies, air quality in the South Bay came close to the Stage 1 smog alert level on Thursday and officials predict more unhealthful air for today.

The peak level of carbon monoxide Thursday was about 14 parts per million, exceeding the federal safe standard of 9.5 parts per million. Officials predict 13 parts per million for today. A Stage 1 alert is declared at 15 parts per million.

During Stage 1 alerts, elderly people and those with respiratory or heart problems are urged to refrain from physical activity.

“This is considered unhealthful air,” said Bill Kelly, a spokesman for at the South Coast Air Quality Management District, which tests the South Bay’s air at a station in Hawthorne.

Carbon monoxide, which is colorless and odorless, is absorbed in the blood and blocks it from getting oxygen, Kelly said. “It basically strangles people,” he said, noting that 90% of carbon monoxide in the air comes from automobiles.

In the winter, high amounts of carbon monoxide are trapped close to the ground by an “inversion layer”--a layer of cold air held down by warmer air.

In addition, car engines take longer to warm up and run efficiently in cold air, resulting in the creation of more carbon monoxide.

“It tends to be worse during late fall and early winter,” he said. “This time of year is when we get it.”

In the summer, the most common pollutant is ozone, which is produced in a chemical reaction with sunlight, he said. Since there is more sunlight in the summer, there is more ozone.