Think China's Pollution Is Bad? Try Northern California

Think China's Pollution Is Bad? Try Northern California

Why you should care

Because dirty air kills thousands of Americans every year.

What comes to mind when you think of the San Francisco Bay Area? Gay pride? Kale-açai-poké smoothies? Space-age corporate mega-campuses in Silicon Valley? Driverless Teslas duking it out with Priuses?

Well, what about toxic air pollution? Because, believe it or not:

Air pollution in San Jose was worse than in Shanghai on 32 out of the 61 days in June and July.

The finding results from comparing Air Quality Index data on particulate matter pollution with measurements made by the U.S. Consulate in Shanghai. The measurement, called PM2.5, counts particles of dust and soot that are less than 2.5 microns in width; a human hair is about 100 microns wide. The average daily PM2.5 Air Quality Index in San Jose for June and July was 34.4, almost exactly the same as measurements made at the U.S. Consulate in Shanghai, where the average was 35.0.

Turns out it’s not just the Bay Area, either. The American Lung Association’s 2016 State of the Air Report found the San Jose-San Francisco-Oakland metro area to be the sixth most polluted city in the U.S. by annual particulate matter, and the five cities that beat the region were all also in California. Bakersfield, in the Central Valley, holds the inauspicious acclaim of being No. 1. Six of the seven top cities in the U.S. for ozone pollution were also in the Golden State, with the Bay Area coming in at number 16 by that measure.

California’s toxic air is “not just a nuisance,” says Bonnie Holmes-Gen, senior director of air quality and climate change with the ALA in California, as pollution “does lead to hospitalizations and health emergencies, and it can kill.” The particulate matter pollution that affects the Bay Area so badly includes soot, ash and dust that can penetrate the lungs and even enter the bloodstream, increasing the risk of heart attacks and strokes as well as respiratory illnesses and lung cancer. There is “a public health crisis from air pollution in California,” says Holmes-Gen, with an estimated 7,000 early deaths per year related to dirty air in the state.

The Bay Area is not usually “a hotbed” for air pollution, in comparison with other places in California, says professor Mark Jacobson, director of the Atmosphere/Energy program at Stanford University, but this year’s high scores can be explained by “a combination of emissions, geography and meteorology.” In particular, wood smoke from domestic fires in the winter, an increasing volume of traffic (even though emissions per mile are falling) and industry emissions from areas such as the port of Oakland contribute to pollution in the Bay Area. Then there’s the Pacific High Pressure System, which prevents polluted air from rising over the mountains. During the summer, it migrates north from offshore L.A. The drought affecting vast regions of the West Coast exacerbates the problem, because “the main removal mechanism of particles in the atmosphere is rain,” says Jacobson. The West Coast’s dryness, combined with heat and sunlight, which catalyze the production of ozone, aren’t as much a feature of other large urban areas on the east coast and even in the southeast. And climate change is only exacerbating the issue.

To be sure, it used to be a whole lot worse, and pollution levels are continuing to fall in most urban areas across the country. Holmes-Gen says there have been “tremendous strides” toward cleaning up the air. Since 1970, while economic output has more than tripled, population increased by half and vehicle miles traveled increased by 172 percent, aggregate air pollution emissions have actually fallen by 69 percent nationwide, according to the ALA. California’s air-quality laws lead the nation, with the state’s vehicle-emissions laws even tougher than the federal standard. “The rules and regulations and investments that the state and the air districts have made, they are working,” says Holmes-Gen, but, of course, “we do have more to do,” particularly in continuing to decarbonize the transport sector and cracking down on diesel emissions.

Admittedly, June and July have been among the worst months for pollution in San Jose, while they are are among the months when the toxic clouds engulfing Chinese cities are at their thinnest. Nevertheless, it makes you look at San Francisco’s famous fog in a whole new light.


Numbers and factoids --- fodder for your next cocktail party.