FRESNO -- Activists are criticizing a 2014 cleanup target for dangerous soot and chemical specks in the valley's air, saying it fits a pattern of delay from regional pollution officials.
"They're not doing everything they can to clean the air," said Liza Bolaños, Fresno-based coordinator of the nonprofit Coalition for Clean Air. Activists said tougher controls might hasten the cleanup by years.
The San Joaquin Valley Air Pollution Control District replied that its proposed plan for cleaning up the specks, called PM 2.5 (particulate matter 2.5 microns or smaller), is the most aggressive approach available. Officials said they pursued every reduction possible.
A similar disagreement took place last year when the valley's ozone cleanup plan was approved. The arguments are surfacing again because measures that control ozone also reduce PM 2.5.
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The tiny PM 2.5 particles -- 30 would fit along the width of a human hair -- can penetrate deep into the lungs, triggering lung and heart problems. The particles are linked with premature death and billions of dollars in health care costs annually.
PM 2.5 comes from fires, vehicles and even commercial charbroiling. It also forms in fall and winter when oxides of nitrogen from vehicles combine with ammonia from dairies. The specks are called ammonium nitrate.
The valley's level of PM 2.5 has been reduced in the past few years, but the problem still ranks among the worst in the state.
The cleanup plan is supposed to come before the district board for possible approval in late April, when activists are expected to again raise their objections.
The district's cleanup strategy for PM 2.5 includes tighter rules on many activities, including the use of fireplaces. But officials are relying heavily on several state Air Resources Board rules. One of them is a hotly debated measure to control diesel truck exhaust.
The state has authority over vehicles, which create about 80 percent of the problem for ozone and PM 2.5.
"We would like to see ARB accelerate the reductions, and we think that might happen," said district planning director Scott Nester.
Activists said the district should not wait for the state. They said technical advances could better control pollution from engines on farm pumps and small boilers, which generate steam, heat and power.
Engineer Alvin Valeriano, a former district employee who now works on alternative air quality solutions, added that the district should consider limits on older trucks, tractors and construction equipment during episodes of high pollution.
"There are very simple, practical steps and proven technologies that would help," he said.