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LOS ANGELES — The California Air Resources Board will consider amending the state’s air quality standards for microscopic pollutants to make them the world’s strictest. 

The revised health standards to be considered Thursday concern a class of pollutants made up of particles of soot and dust one-seventh the diameter of a human hair or smaller. 

The tiny particles have been linked to the deaths of thousands of Californians each year. 

The revised standards could exceed those set by the U.S. Environmental Protection Agency but would lack the penalties contained in federal law. 

“The state standards don’t have the teeth of the federal standards. But they are the state’s definition of what healthy air is, and as such we will work to attain them,” said Air Resources Board spokesman Jerry Martin. 

The proposed amendments would target the state’s annual ambient air quality standard for particles smaller than 10 microns in diameter, or so-called PM10s. A human hair is about 70 microns in width. 

The Air Resources Board estimates that 99 percent of Californians are exposed to air that on an average daily basis exceeds current health standards for PM10. 

Bonnie Holmes-Gen, a lobbyist for the American Lung Association of California, said those standards have not been reviewed for 20 years. 

“Since then, there have been hundreds of new studies on premature mortality, emergency room visits, school absences and other health impacts related to elevated particle levels in the air,” Holmes-Gen said. 

Last month, the Environmental Working Group, a Washington, D.C., advocacy organization, claimed particulate pollution kills 9,300 Californians a year. 

The Air Resources Board estimated that 2,431 tons of the dust and soot were emitted each day in California in 2001 from sources including farms, construction sites, wildfires and the tailpipes of cars, trucks and buses. Dust from roads is the largest single source of the particulate pollution. 

The board will consider dropping the annual average standard to 20 micrograms per cubic meter of air, from the current 30. Standards for daily averages would remain unchanged. 

Cass Andary, director of regulatory programs for the Alliance of Automobile Manufacturers, said the Southfield, Mich., group opposes the new standards.