As California's wine country burns, smoke from the wildfires have blanketed the Bay Area, drowning out the sun and taking the air quality down to unhealthy levels.
"We're seeing elevated levels of particulate matter (PM) that are higher than we've ever seen since we began measuring that in 2000," Lisa Fasano of the Bay Area Air Quality Management District said Wednesday.
On Thursday, levels of the particle pollution known as PM2.5 hovered at 160 micrograms per cubic meter — or 14 times higher than what federal standards deem safe — around the San Francisco area. In Napa, the air quality index was 174 by 1 p.m. PT and forecast to reach a "very unhealthy" level of 210.
These tiny particles are about 3 percent of the diameter of a human hair, which makes them even more dangerous because they can be inhaled into the lungs and bypass the body's filtration systems, slipping directly into the bloodstream.
"This is not the kind of thing that you want to have people out running and breathing in," Fasano said. "It's very hazardous."
Sean Raffuse, an air-quality analyst at the Crocker Nuclear Laboratory at University of California in Davis, told the Reno Gazette-Journal that early estimates project the fires have already produced about 10,000 tons of PM2.5. That is the same amount of pollutants that all of California's 35 million cars produce in a year.
Jim Roberts, a research chemist from the National Oceanic and Atmospheric Administration’s Earth System’s Research Laboratory, told NBC that Rafusse's calculations "sounds about right."
Air quality specialists said such high concentrations of PM2.5 are particularly unhealthy for sensitive groups such as people with asthma and other respiratory conditions, the elderly and kids.
Schools are keeping students indoors, even during recesses, and sports teams were canceling practices and games.
"We've got kids from ages 7 years old all the way up to 19, so we always try to keep the best interests of the children in mind," said Chris Pepe, general manager of Juventus Sport Club, a soccer team in Redwood City.
According to the Enviromental Protection Agency, both short- and long-term exposures to high levels of PM2.5 concentrations have been shown to lead to harmful health effects, including links to death. In addition, the agency says scientists have observed higher rates of hospitalizations, emergency room visits and doctor's visits for respiratory illnesses and heart disease during elevated PM2.5.
To reduce exposure to these fine particles, California's Air Resources Board advises residents to try to stay indoors and consider purchasing an air filter for your home. People in high risk groups are urged to avoid activities that make you breathe faster or more deeply.
The agency also warned against relying on dust masks for protection. Paper masks are designed to trap large particles, such as sawdust, and will not protect your lungs from small particles such as PM2.5. Scarves or bandanas won’t help either. Disposable respirators known as N-95 or P-100 respirators will help if you have to be outdoors for a period of time. It’s important that you wear the respirator correctly, however. For more information on N-95 or P-100 respirators and how to use one, click here.