If you want to measure how much air pollution exists on streets and freeways, there’s no substitute for sticking a pipe out a car window and sucking air in.
In simple terms, this is the work of a gray RAV4 that has been traveling Sacramento area roadways recently measuring pollution from vehicles.
The electric car is operated by the California Air Resources Board – the agency charged with reducing greenhouse gas emissions and implementing air pollution regulations.
The instruments that peek out of the vehicle often lead curious onlookers to mistake it for the Google car, said Kathleen Kozawa, an atmospheric scientist with the Air Resources Board.
Dubbed a “mobile measurement platform”, the RAV4 feeds data to agency scientists, such as Kozawa, who seek an accurate accounting of such pollutants as nitrogen oxides, black carbon and ultrafine particulates.
The Toyota is crammed from trunk to front seat with more than $300,000 of scientific measurement equipment. It’s one of two such air monitoring cars in the state; the other measures pollution on roadways, freeways and ports in the Los Angeles region.
The roadway measurements are meant to supplement the more than 250 stationary air monitoring sites located throughout the state. There are 12 in the Sacramento region. These measure a wide range of pollutants, some by the hour, with monitoring done 24 hours a day.
“We have a whole spectrum of tools to measure air emissions,” said Michael Benjamin, chief of air monitoring. In its labs, the Air Resources Board measures emissions from tailpipes of cars, trucks and off-road equipment. But it does not get an adequate picture about roadway conditions without using its vehicle.
“It’s kind of like connect-the-dots. The 12 stations in the Sacramento area are like dots, and we infer what the air quality is between those dots. What the mobile platform allows us to do is verify that and fill that in with additional measurements. It paints a thorough picture about what air quality is in any given community.”
On Tuesday morning, with noon approaching, the RAV4 made a stop on 34th Street in Oak Park in front of Sacramento Charter High School to take measurements. The school is located three blocks from the busy freeway intersection of Highway 99 and Highway 50.
Logic would suggest that pollution readings would be high at the school. Not so, said Kozawa, who typically pilots the vehicle while a colleague sits in the jump seat and tracks measurements on a laptop. The readings were low and stable, with few spikes in pollutants.
On Tuesday, the highest and most wildly fluctuating pollution levels were recorded not while the RAV4 traveled the freeway, but on Marconi Avenue near the intersection with busy Watt Avenue.
“If we came here every day and did a few hours of measurement every day over a period of time, a picture would emerge,” Kozawa said.
One picture is beginning to emerge from such monitoring: Over time, the air is getting cleaner at many locations. Agency officials attribute this improvement to the state’s new rules mandating cleaner diesel trucks and buses.
“Pollution is getting better in Southern California, especially emissions from diesel trucks on freeways,” Kozawa said.
Some of the findings gleaned from the RAV4 air monitoring vehicle may be as surprising as they are elemental – like the fact that freeway pollution can spread widest during the early morning hours, before rush hour begins. At that time, the air is generally calm.
“When it’s really calm outside – with no wind – that’s when you can see impacts as much as a mile and half away from a freeway,” Kozawa said. “It’s then that the plume goes up and meanders all the way into a neighborhood.”
Call The Bee’s Edward Ortiz, (916) 321-1071. Follow him on Twitter @edwardortiz.