Two weeks after telling employers they "must consider" taking steps to protect outdoor workers from wildfire smoke, California’s Department of Industrial Relations Tuesday released a more strongly-worded new advisory telling employers that they must protect workers exposed to hazardous particulates from fires.

The tougher stance follows KPCC's report last week that a Dec. 6 advisory issued by Industrial Relations' Division of Occupational Safety and Health left it up to employers to decide which steps to take to protect workers exposed to smoke, such as limiting their time outdoors or issuing face masks. The advisory only said businesses "must consider taking appropriate measures."

KPCC also found that many farmworkers continued to work in smoky conditions during the Thomas fire, some without face masks.

The new Cal/OSHA advisory says explicitly that if workers are exposed to air that’s been designated as “unhealthy," "very unhealthy," or "hazardous," their employers "are required to provide filtering respirators such as masks labeled N95 and certified by the National Institute for Occupational Safety and Health."

The N95 masks, which are recommended by public health officials, filter at least 95 percent of airborne particles. The advisory lists locations where the public can find the masks.

Cal/OSHA spokesman Peter Melton insisted the agency’s safety guidelines haven’t changed.

“Employers are required at all times to identify and address hazards in every workplace,” he said in an email. “Cal/OSHA’s wildfire advisories concern which measures employers must consider in order to address the hazards associated with the wildfires at their particular workplace rather than a one-size-fits-all approach.”

Farmworker advocates cheered the new advisory. They had criticized the Dec. 6 guidance as too vague.

"Essentially what we had before was a requirement to think about it really hard," said Lucas Zucker, policy and communications director for Central Coast Alliance United for a Sustainable Economy, which sent volunteers to distribute protective masks to farmworkers in the Oxnard and Santa Maria areas.

Now, Zucker said, "it's not 'you must think about it,' it's, 'You must provide.'"

Oxnard farmworker Amadeo Sumano told KPCC that he showed up at the strawberry farm where he works the morning after the Thomas fire began and "we saw the hills full of smoke."

“Our eyes hurt," said Sumano, 38, an immigrant from the Mexican state of Oaxaca. "And breathing, too. We were starting to get runny noses ... and our throats, and also our heads."

He said his employer provided workers with protective face masks two or three hours later, but he said he knew of other workers on farms where growers were slower to act.

Farmworker advocates reported finding numerous farm workers in the Oxnard and Santa Maria farming areas without protective masks while the air quality was very poor.

This story was updated to add Peter Melton’s comment, and to clarify that a Dec. 6 advisory left it up to employers to decide which steps to take to protect workers, rather than leaving it up to employers to decide whether to take steps to protect workers. KPCC regrets the error.