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August/September 2014

Data-Driven: Regulators Monitor Air Quality Near Roadways

By Alec MacDonald

A seemingly endless network of asphalt offers drivers the mobility to roam all across the Bay Area. But that freedom comes at the expense of others — residents stuck choking on the noxious fumes spewed out by so many passing vehicles.

Living alongside a steady stream of traffic exposes people to a variety of hazardous substances, such as particulate matter, carbon monoxide, nitrogen dioxide, benzene, and formaldehyde. Epidemiological studies connect this exposure to asthma exacerbation, impaired lung function, and cardiovascular morbidity, among other alarming ailments. In a comprehensive survey of relevant scientific research, the nonprofit Health Effects Institute determined that these circumstances “are likely to be of public health concern and deserve public attention,” especially given that, in large North American cities, 30 to 45 percent of the population dwells within a potentially hazardous 300 to 500 meter proximity of major roads.

For decades, the Environmental Protection Agency has attempted to ameliorate the problem by enacting stricter vehicle emission standards and cleaner fuel requirements. More recently, the agency has also sought to better quantify the situation, instructing state and local authorities to begin monitoring air quality close to certain traffic hot spots. This effort will fill a critical need, because for all the epidemiological evidence proving that living alongside congested corridors carries negative health implications, “there’s no long-term air monitoring data on a wide-scale basis for policy makers to determine what might be the cause,” according to Eric Stevenson, director of technical services for the Bay Area Air Quality Management District.

As the region’s air pollution control agency, the Air District already collects copious monitoring data at 31 stations around the Bay Area, but none of those stations stand by any thoroughfares. “We specifically try not to monitor near roadways, because the near-roadway concentrations tend to be very localized,” Stevenson explained. However, after receiving the EPA’s directive, the Air District initiated plans to erect three new monitoring stations adjacent to Bay Area highways. Taking into consideration factors such as traffic volume, vehicle types, congestion patterns, infrastructure design, topography, meteorology, and demographics, the Air District selected sites next to Interstate 80 in Berkeley, Interstate 280 in San Jose, and Interstate 880 in Oakland.

The Berkeley and San Jose stations should go live soon, while the Oakland one has been up and running since February. Housed within a trailer at the edge of a Laney College parking lot, it looks unremarkable and dormant, but its sophisticated instrumentation remains ever busy, taking continuous measurements of ambient air coming off the lanes just 20 meters away. The station collects data on soot, carbon monoxide, nitric oxide, nitrogen dioxide, fine particulate matter, and various toxic hydrocarbons. After a little number-crunching to generate hourly readings in almost all of these categories, the Air District publishes the results on its website for anyone to see.

Although the station has gathered reams of information thus far, Stevenson contended it’s still too early to declare anything definitive about the findings, noting that “usually we like to collect a year’s worth of data before we start drawing conclusions.” When that time approaches, air quality experts everywhere may want to take heed, since the Oakland station and its two counterparts stand as frontrunners for yielding insights in the broader EPA roadway monitoring investigation.

“A lot of these stations haven’t been deployed yet, so there’s only a few throughout the nation that have come online,” Stevenson said. “We’re actually kind of ahead of the game.”

Alec MacDonald is the editor of the Bay Area Monitor.