Which mask is best for bad air?

SAN FRANCISCO (KGO) -- With so many fires burning, we need to be careful. Experts say that wildfire smoke is dangerous because it contains fine particulates that can lodge deep into the lungs. That can cause or worsen respiratory issues, such as asthma. Some groups are especially vulnerable, including children and older people. Healthy people are vulnerable as well. High levels of particulates in the air can trigger acute symptoms like difficulty breathing and headaches.

RELATED: Check current Bay Area air quality levels

Health experts agree that the best defense is to stay indoors. But if that's not an option for you, it is best to wear the right kind of mask.

The California Governor's Office of Emergency Services and the California Department of Public Health recommend "N95" respirators or "P100" masks, both of which are approved by the National Institute for Occupational Safety and Health for health care workers and firefighters.

Those masks are intended to block at least 95 percent of the hazardous and tiny particulate matter (known as PM2.5). That is what most commonly spews from wildfire smoke. At 2.5 microns or less in diameter, the particles of PM2.5 can't even be seen by the naked eye. For comparison, a human hair can measure as little as 16 microns in diameter.

Once you find the right kind of mask, it's also important to wear it correctly.

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The mask should have two straps. One strap should be placed below the ears and one above. And the mask should seal tightly to your face.

But if you have difficulty breathing or become dizzy, remove the mask.

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When a disposable mask gets dirty inside or you have trouble breathing, throw it out.

The N95 masks aren't small enough for most children. Experts warn that while you may use adult masks on children, there is no guarantee they will be effective. They say, it is better to keep children indoors until air levels have returned to a safe level.

The masks don't block all the toxins in the air. Some chemical gases that are released in a wildfire from burning construction materials, cars, paint and other consumer goods may still get impact people.

See more stories, photos and videos on the Camp Fire in Butte County here.