County Registers Improvement in Cleaning Up Air

San Diego County met another state air quality standard by reducing its levels of nitrogen dioxide over the last three years, but the county is still a way off from reaching the same standard for smog, air pollution authorities announced Tuesday.

A reduction in automobile emissions contributed to the county’s ability to meet state nitrogen dioxide standards from 1989 through 1991, said Bob Goggin, spokesman for the county’s Air Pollution Control District.

Nitrogen dioxide is one of nine pollutants included in the state’s Regional Air Quality Strategy, which establishes air quality standards for the state’s counties, Goggin said.

So far, San Diego County has met six of the standards and is two years away from meeting a seventh standard for carbon monoxide, Goggin said. Carbon monoxide levels show a downward trend since they exceeded state standards only once in 1990, and not at all in 1991.

But acceptable levels of smog and particulates such as dust or diesel emissions will be more difficult to attain, Goggin said.

The county exceeded state smog standards 106 days last year. To meet the regional air quality requirements, the county would have to spend three consecutive years without exceeding the standard on any days.

But smog improved during the past decade. The county exceeded state standards an average of 166 days a year from 1979 to 1981, Goggin said, contrasted with an average 134 days a year from 1989 through 1991.

The intensity of smog also decreased since 1980, when eight smog alerts were issued. In 1990 there was only one smog alert, Goggin said.

Goggin said his agency will now ask the state to designate San Diego County as meeting state nitrogen dioxide standards and also acknowledge that the county is in the process of reaching carbon monoxide standards.