These two pollution sources are worrying SLO County air quality officials

San Luis Obispo County has generally enjoyed clean air in recent months. However, one chronic problem and one new problem have county air quality officials concerned.

Air quality on the Nipomo Mesa continues to suffer from dust blowing from the Oceano Dunes State Vehicular Recreation Area. The monitoring station at a Cal Fire station immediately downwind from the riding area exceeded state particulate standards 62 times in 2015.

“It is a significant health concern,” county Air Pollution Control Officer Larry Allen told the San Luis Obispo County Air Pollution Control Board on Wednesday. “Health effects from particulates tend to be immediate and can cause hospitalization.”

Also, diesel fumes from idling Union Pacific Railroad locomotives in residential areas in San Luis Obispo south of Tank Farm Road have been an emerging air quality problem since November, Allen said.

“It’s a pretty nasty problem in that neighborhood,” he said.

At Wednesday’s meeting, the board unanimously approved spending as much as $50,000 to help purchase an electronic air compressor that would eliminate the need to idle the trains. The railroad and the city of San Luis Obispo will contribute equal amounts of money for the compressor, which is expected to cost up to $150,000.

Trains idle for hours on a siding in the Arbors and French Park neighborhoods to let passenger trains pass. At least one locomotive needs to idle to maintain air pressure in the train’s brake system. The electric compressor would eliminate this need.

San Luis Obispo Mayor Jan Marx said her office receives several emails each day from neighborhood residents complaining about the odors and noise from the idling locomotives.

“It really burns me up that UP is not going to pay all the cost for this,” she said. “I think it should be part of their cost of doing business.”

The locomotives idle for an average of four hours but can idle for 24 hours or more depending on rail traffic patterns.

At the Oceano Dunes, State Parks is preparing an environmental impact report that evaluates dust control measures used in the park. The agency has been using wind fences and vegetation planting to reduce blowing dust in recent years.

Nipomo Mesa resident Arlene Versaw told the board the state’s particulate monitoring standards are flawed because they average out dust levels over a 24-hour period.

A better standard would be between 10 a.m. and 4 p.m. when the blowing dust is at its worst, she said.

“That’s when residents have to live with it,” she said.

This story was originally published September 28, 2016 at 5:05 PM with the headline "These two pollution sources are worrying SLO County air quality officials."