Air district explains ‘Spare the Air’ process

On a winter with record-breaking stretches of rainless days, the Bay Area Air Quality Management District has declared a record-breaking number of Spare the Air alerts. And that in turn seems to have led to more than the usual number of complaints and criticisms.

“We hear them every day, all the time,” said Ralph Borrmann, the district’s public information officer, referring to criticisms made directly to BAAQMD officials. “So we’re well aware of them and we’re happy to speak to them, because our work is based in science.”

Many of the criticisms question the effectiveness of the district’s Spare the Air policy, which prohibits the burning of wood, pellets or other solid fuels on specified days. (First-time violators can receive a fine of $100, and the cost goes up from there.) But some say the district’s method for declaring Spare the Air days in the first place is flawed, self-serving or even conspiratorial.

So how does the Bay Area Air Quality Management District determine which days are OK for burning, and which aren’t?

To begin with: data. According to Kurt Malone, BAAQMD’s supervising air quality meteorologist, weather information is “provided to us twice daily at three hourly increments extending out 72 hours.” This isn’t just National Weather Service data, but highly detailed information from various sources on Bay Area conditions.

Then there are the district’s ambient-air sensors. These are located throughout the Bay Area, and different sensors are designed for different purposes. The ones of interest during the winter season – which for BAAQMD’s purposes extends from November to the end of February – are 12 or 13 sensors detecting “PM 2.5,” meaning particulate matter of 2.5 microns or smaller.

A particle 2.5 microns across is very small, perhaps one-60th the width of a human hair. “It’s so small that it can penetrate the blood-lung barrier,” Borrmann said, resulting in serious health problems – which is what the district is trying to guard against. And in the Bay Area, an estimated 40 percent of these tiny particles come from residents burning wood, Borrmann said.

“People make the observation that we’ve been burning wood since the Stone Age and what’s the big deal all of a sudden,” Borrmann said. The answer, he said, is that modern science makes clear what we didn’t always know: In high enough quantity, tiny particulate matter can be deadly, especially to young children and the elderly.

In the recent past, “We were not meeting federal air quality standards for particulates,” Borrmann said. “And as you, know standards get more protective over time.” Because the district’s voluntary program wasn’t working, officials started mandatory compliance in 2008 – resulting, they say, in overall cleaner air.

With this in mind, every day the district’s three meteorologists pore over – and sometimes argue over – the data in an attempt to accurately predict tomorrow’s pollution levels. They’ve been analyzing Bay Area data for more than 12 years, Malone said, looking at patterns in the way certain conditions lead to certain particulate levels.

“We have professional fights, it always stays cordial, and then we kind of chide each other the next day,” Malone said.

Although “sometimes we’ll bet a pizza or something,” the meteorologists usually come to a consensus, he said.

Their conclusions, this winter, have been difficult for fire-lovers to take: 11 no-burn days in a row from Dec. 8 to 18, then again from Dec. 23 to 29. One day off, on Dec. 30, was followed by five more Spare the Air days from Dec. 31 to Jan. 4. But the weather-watchers say that’s what this dry, static and very long-lasting weather system has called for.

As for Dec. 30, “The one day that we didn’t put the restrictions in, we exceeded the national standard,” Malone said. (The nine-county region has exceeded the national standard for air pollution, set by the Environmental Protection Agency, 14 times this winter, according to district officials.)

Of course, total certainty is elusive when it comes to predicting tomorrow’s pollution levels, not only because weather is dynamic but because human behavior is even harder to predict. How many people will decide to have wood fires tomorrow? And if a Spare the Air day is called, how many of them will burn anyway?

Furthermore, “It’s very true that air quality varies by region,” Malone said. But the district is a Bay Area-wide entity, and is tasked with managing air pollution per federal standards throughout all nine counties – so data from its sensors are taken altogether, and a decision made with everyone in mind.

The closest BAAQMD sensor to Sonoma is located on Jefferson Street in Napa. Others are located in Fairfield, Vallejo, Crocket, Rodeo and Martinez. A new district sensor was scheduled to come online this week in Sebastopol.

Recently, an anonymous Napa resident said in an online blog that the district’s sensor in that city gives incorrect data due to its location atop a Mexican bakery. He also accused the district of purposely using this sensor to manipulate its results in order to declare more no-burn days.

Glen Colwell, the district’s air monitoring section manager, said the district audits its 32 sensors on a yearly basis, looking for changes in the environment around each sensor that might alter its results.

For example, a tree growing too close to a sensor can act as a “scrubber,” making the air too clean for accurate readings. When that happens, “We have to cut the tree down, which is what we did in Napa,” Colwell said.

“Of course if an auto body shop or a charbroiler moves in next door, we’re going to have a lot of concerns,” he said. However, “In the case of the Mexican bakery, that business utilizes a natural gas-fired oven,” meaning particulates are not being released too close to the sensor.

Overall, Colwell said, “Restaurants are a part of the ambient air emission mix, if you will.”