For the past 11 days, the air has been so dirty that the Bay Area’s air-monitoring body has issued warnings to the public. That’s the longest stretch of consecutive Spare the Air days.
“It is unprecedented to have 10 in a row like this,” said Aaron Richardson, spokesman for the Bay Area Air Quality Management District, on Tuesday before the 11th day of Spare the Air alerts was declared. “It actually doubled the previous record for consecutive days.”
Those warnings — which were first issued in 1991 — are announced whenever the amount of small particles in the air reaches a threshold the federal government has deemed unhealthy.
While pollution from industry, wood smoke, automobiles and other sources is never good for human health, these elevated levels can be especially bad for people with breathing problems.
The alert — which warns healthy people to refrain from exercising and people with respiratory illnesses to stay indoors — also restricts the use of wood-burning stoves.
The air, Richardson said, is as bad this week as in past years when forest fires brought unhealthy levels of soot to the area.
“We’ve just had this really long, gross and dirty and stagnant stretch where there’s been an inversion layer trapping the air near the surface like a smoky room,” he said.
So far this winter season, which runs from Nov. 1 through Feb. 28, there have been 14 Spare the Air days. Last year, there were only 10, while in winter 2006, for instance, there were 30.
San Francisco usually has better air quality than the rest of the Bay Area because of the prevailing onshore winds from the Pacific, but there has been little of that wind in the past week.
As for the fire at a San Mateo County recycling plant early Tuesday, it has mostly just made the already bad air in the South Bay worse.
While several hospitals contacted by The San Francisco Examiner did not say they were seeing an increased number of patients with respiratory illnesses, air pollution impacts people with lung illnesses as well as cardiovascular issues.
A weather system is forecast to move into the area later this week and is expected to clear out the stagnant air over San Francisco.
• 1.4 million: Wood-burning stoves in the Bay Area
• 30 percent: Amount of air pollution created by those stoves
• P.M. 2.5: Particulate matter size, which has a particular impact on public health; 35 micrograms per cubic meter in a 24-hour period triggers a Spare the Air day