SAN FRANCISCO — Air quality in parts of southern California near raging wildfires reached hazardous levels on Thursday, prompting local officials to close some schools and urge those with chronic diseases to stay indoors to protect their lungs.
Faced with smog and soot in the air, many people grab a mask to cover nose and mouth. But beware: the type of mask matters if you're trying to ward off dangerous levels of particles and toxins created by the multiple fires.
The flat, soft doctor-type masks worn in hospitals are designed to keep germs in, not keep pollution out, and don't do anything to protect against smoke.
"Those are worse than useless because they give you a false sense of security," said Catherine Forest, a physician and expert on environmental toxins at Stanford Health Care in Palo Alto, Calif.
In Goleta, to the northwest of Los Angeles, the official Air Quality Index at 11:00 am Thursday was 238. A real-time monitor near Santa Barbara showed a stunning 431. A safe level is between 0 and 50, according to the U.S. Environmental Protection Agency.
"These are astounding levels," said Michael Jerrett, chair of the University of California-Los Angeles Environmental Health Sciences department.
"They're now into what’s known as a Maroon Alert, so it’s above a Red Alert. The only other time I’ve ever experienced that was in Beijing in China when they were having a pollution event," said Jerrett, who studies pollution and wildfires.
The good news is that much of the greater Los Angeles area was not affected by the fires, and even areas where there was some smoke had better air quality on Thursday than the previous days due to shifting wind patterns. The area near UCLA was near normal on Thursday, said Yifang Zhu, a professor of environmental health sciences at UCLA.
For the right mask, hit the hardware store
To protect lungs by keeping particulate matter out, an OSHA-approved N95 particulate filtering mask is necessary. This can often be found in the painting or woodworking supplies section of hardware stores.
There are also tricks to making them as effective as possible. First is to get the right size. While hardware stores typically only sell the large size of the masks, they actually come in three sizes, small medium and large. Try medical supply stories for the smaller sizes that tend to work better for women and children, experts suggest.
Next, bend the flexible metal strip at the top of the mask so that it fits the curve of the nose, to get it the tightest possible fit.
"They have to seal around, like a snorkel mask," said John Balmes, a pulmonologist at the University of California-San Francisco who has studied the respiratory health effects of air pollutants for over 25 years.
Don't go out
The best advice for those in affected areas is to simply stay indoors with the windows shut and air conditioning or heaters set to recirculate air, said Stanford's Forest.
"Don't go out if you can avoid it, don't exercise if you can avoid it. Keep the elderly, small children and anyone with heart or lung disease inside," she said.
For those in their cars, keep windows rolled up and put the air system on recirculate rather than having fresh air come in from the outside.
"We've done tests and while it depends on the type of filter your car uses, you generally get somewhere between a 40% and 60% reduction in the particles getting into the car," said UCLA's Zhu.
Another option is to run a home air filter. As long as it’s got a HEPA (high efficiency particulate air) filter can catch most fine particles, defined as 2.5 microns in diameter or less, which can irritate lungs.
“They’re so small you can’t see them, but they’ll make you cough,” said UCSF's Balmes.
The trick with HEPA filters is to regularly clean or change the filters, said Stanford's Forest. You can’t just buy them and run them forever without putting in a new filter, "or they end up not doing anything at all."
Not a long-term threat
Overall, the poor air quality shouldn't pose a long term threat to healthy individuals as long as it doesn't last more than a few days, say the experts.
However such acute events do increase emergency room visit and hospital visits, particular for people who are susceptible. That includes children, pregnant women, people with preexisting lung or heart disease and people who are diabetic, said UCLA's Jerrett.
Most healthy adults will experience annoying but not dangerous symptoms. "People will have stinging eyes, trouble breathing, scratching throats and running noses," Stanford's Forest said.
The good news is that healthy lungs are remarkably self-cleaning, she said. They’re lined with mucus-coated, hair-like projections called cilia. The mucus catches the tiny particles that we breath in and then the waving, beating motion of the cillium moves them up and out of the lungs.
"It’s kind of like a little escalator. It carries it up out of your lungs and you either swallow or cough it out. Either is fine,” she said.