Particles added to daily air forecasts

Fine pollutants now part of calculations to determine air quality.

By Barbara Anderson
The Fresno Bee

(Updated Friday, January 3, 2003, 10:29 AM)

This winter San Joaquin Valley residents will wake up to more days of unhealthful air and warnings to not burn wood in fireplaces or to set piles of farm prunings afire.

The reason: Fine particles, known as PM2.5, became part of the daily air-quality forecast beginning Wednesday.

If the first three days of including PM2.5 in air-quality forecasts are an indication, the Valley could be in for a string of unhealthful air days.

Fine particles catapulted air quality into the unhealthful range Wednesday and Thursday. Today's air quality forecast -- 153 on the air-quality index -- means unhealthful air between Madera and Bakersfield. Farmers cannot burn agricultural waste today. An AQI above 150 constitutes unhealthful air.

"We knew this was going to happen," says Josette Merced Bello, spokeswoman at the San Joaquin Valley Air Pollution Control District. "PM2.5 constitutes a greater health risk at lower measured levels."

In other words: Fine particles trip the AQI sooner than larger particles known as PM10. Before Wednesday, only PM10 levels were used to calculate air quality. Measuring fine particles was added to comply with federal Environmental Protection Agency health standards.

The Valley air district collects fine particles at monitoring stations in Fresno, Visalia, Bakersfield, Corcoran and Modesto. These fine particles are smaller than 2.5 microns in width, or about 1/28th the diameter of a human hair, and can easily burrow deep inside the lungs. The particles are known to aggravate asthma attacks and bronchitis. Air-pollution researchers link the particles to heart attacks and in some cases, cancer.

Unlike PM10, which can come from dust, fine particles are the by-product of combustion of wood, vegetation or gasoline.

Fresno environmental activist Kevin Hall says it's a relief that fine particles are part of the mix of pollutants now being measured. "It's critically important to human health that people at risk of asthma attacks and heart attacks are made fully aware of the true levels of air pollution on a daily basis," he says.

For cotton farmer Paul Betancourt, extra no-burn days are not a surprise. "This is the time of year when we go out of compliance," he says.

Having more no-burn days will not adversely affect farmers, he says. "Fortunately, burning our prunings is not a time-sensitive issue."

Waiting a few days until the air clears to burn is acceptable. "We're willing to do our part, and if our part means we have to wait a little bit [to burn], that's fine."

As fog rolls into the Valley after recent rainstorms, residents can expect the air quality to deteriorate even further. Fog traps the particles close to the ground. "It makes an unhealthy fog, a dirty, sooty fog," Bello says.

Fresno respiratory therapist and clean-air advocate Kevin Hamilton cautions people about being outdoors in the early mornings on unhealthful air days in the winter. "When the AQI is over 100, people who are in the at-risk category should not be spending a lot of time outdoors," he says. The at-risk groups include children, the elderly and people with chronic heart or respiratory health problems.

"The particles are just as bad, if not worse than ozone, and we cannot let our guard down in the wintertime in the Valley. That's unfortunate, but that's the way it is."

The reporter can be reached at banderson@fresnobee.com or 441-6310.