When BART strikes, commuters who rely on BART drive to work or take other means of transit, creating more air pollution.

This year, there were two strikes, totaling eight days, putting the regional transportation service out of use to tens of thousands of commuters. So how much did pollution increase?

It’s hard to tell.

In 2001, the Bay Area Air Quality Management District projected that a seemingly-imminent BART strike would increase air pollution by 35 to 70 tons a day. BART’s daily ridership was 324,000 at the time. Since then, ridership has grown by 19 percent to 400,000. That means daily air pollutant output from BART riders using alternate means of transportation would  increase by roughly 42 to 84 tons a day.

However, much has changed in the past 12 years. There are new and hard-to-calculate factors to take into account. For instance, Bay Area vehicles have been running 2 to 3 percent cleaner each year for the past few years, according to the air quality district spokesperson Ralph Borrmann. Also, there are more green vehicles and cleaner burning fuels. Telecommuting is available to more workers than ever. Smartphone applications make it easier than ever to find carpools.

Looking at toll data from six Bay Area bridges, it appears many workers telecommuted on Friday Oct. 18 or avoided the 5:00 to 10:00 a.m. commute period. When it comes to the environment, no commuters is the best for clean air.

What the 2001 estimate does not account for is pollution produced by vehicles idling in traffic. On Oct. 21, the Monday while BART was still on Strike, 10 percent more vehicles went through toll plazas, creating a lot of traffic congestion.

The Metropolitan Transportation Commission developed a BART strike regional contingency plan to supplement transit services in the Bay Area. In July, AC Transit’s ridership increased by 150 percent and Water Emergency Transportation Authority ferry services increased by 200 percent and carpooling increased on the Bay Bridge by 30 percent.

Complete figures for the October strike are not yet available.

What’s certain is that the Quality Management District did not call for a Spare the Air Day during any strike day. There are various reasons for this, namely that air circulation was good enough to disperse particulate matter. There was pollution but not enough to be overtly concerned.

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Alexander Mullaney is a journalist and publisher in San Francisco. In 2008, he founded The Ingleside Light, a monthly neighborhood newspaper with a circulation of 10,000. In The Ingleside Light he reports on community affairs and publishes the work of both local and student journalists and photographers. He sits on the board of directors of the Geneva Car Barn and Powerhouse, the Ocean Avenue Association, and the San Francisco Neighborhood Newspaper Association. In the summer of 2013, Mullaney organized and managed two community journalism courses for youth with City College of San Francisco and the non-profit Geneva Car Barn and Powerhouse. The pilot program paid students stipends, offered both high school and college credit, and published their articles and photographs in The Ingleside Light. He intends to find funding to offer the program in 2014. Mullaney holds a bachelors degree in creative writing from San Francisco State University. He is studying multimedia and longform writing at UC Berkeley's Graduate School of Journalism. He plans to use his time at graduate school to expand his reportage to produce stories for the public good.

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