It might be hard to believe, but the Los Angeles region once suffered from air pollution akin to that found in today’s Beijing.
Southern California has worked to improve air quality by cutting back on pollution from cars, industrial plants, trash incinerators, and other sources, and the region has come a long way since the 1950s and 1960s.
But this summer has seen setbacks. A punishingly hot season, a scarcity of rainstorms to clear out stagnant air, a landscape desiccated by drought, and explosions of wildfire have conspired to send air quality into a tailspin. Ozone pollution has skyrocketed to levels not seen in at least seven years, with levels exceeding federal standards of 70 parts per billion for more than 90 days so far this year, far above the 67 measured last year. Meanwhile, fine particulate pollution is also up – exacerbated in part by wildfires. The result has been a surge in hospital visits from people suffering asthma attacks and other health problems.
The climate-air pollution link
Where does climate change fit in this picture? Well, studies of California’s ongoing drought suggest that the lack of rain cannot be attributed to climate change, Columbia University’s Adam Sobel told the PBS’s NewsHour on Aug. 17.
However, “the hotter temperatures that we see as a result of human influence on climate cause water to evaporate from the soils more quickly, and so you have overall a drier land surface and lower reservoirs and all of that,” Sobel said.
“And that, there, there is a climate-change influence. So if you ask about the lack of rainfall, this event appears to be largely natural, is what the studies have shown. But if you ask about the overall dryness of California, there does seem to be some influence of higher temperature, which is a result of climate change.”
Previous reports, one of them in The New York Times as early as 2014, pointed to studies suggesting that climate change has most likely intensified the drought in California. “The odds of California suffering droughts at the far end of the scale, like the current one that began in 2012, have roughly doubled over the past century,” the Times reported, citing the view of climate scientists.
A bowl of pollution
In the Los Angeles basin, surrounding mountains combine with temperature inversions to trap dirty air. And this summer in LA, persistently hot temperatures have accentuated those effects. Summarizing the view of a regional air quality official, the Los Angeles Times on Aug. 11 reported that “abnormally hot, stagnant weather, including some of the strongest, most persistent pollution-trapping inversion layers in years” is responsible for the sharp increase in smog.
Philip Fine, deputy executive officer for the South Coast Air Quality Management District, went on to say that it’s unlikely that increased emissions of pollutants are to blame for the increased smog. That’s because a wide variety of regulations in California have required increasingly cleaner vehicles on the state’s roadways.
Future efforts to reduce ozone levels to meet federal standards will require massive emissions cuts in coming decades, the LA Times piece reported. But even with those reductions, “climate change will complicate those efforts by increasing the number of extremely hot days that are prime for ozone formation.”
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Separately, an Associated Press story that ABC News carried on Aug. 23 reported on a new study of similar air quality challenges facing the Southeast.
The research, published in the Proceedings of the National Academy of Sciences, suggests that drier, warmer weather in the fall in the Southeast, which has become more common, may extend summer smog well into the season. One reason, the study found, is that the region’s lush woodlands, stressed by drought, release a chemical called isoprene to protect leaves from drought conditions. And isoprene combines with sunlight to produce smog. The findings are inconclusive, but they “suggest that climate change threatens air quality in ways few people expected,” the AP story said.
“Climate change is about more than sea ice and polar bears,” Ashley Lawson, a senior fellow at the Center for Climate and Energy Solutions, told the AP. “It is also about whether the air will be safe so your children can go play outside.”
Back in California, a new study by scientists at New York University and the American Thoracic Society, released on Aug. 10, estimated that more stringent air quality measures in California could prevent 3,632 deaths a year. That’s more than one third of the 9,320 early deaths caused by air pollution nationwide.
A bit of good news: On Aug. 23, fire officials announced that the devastating Blue Cut Fire east of Los Angeles was 100 percent contained. Raging for a week, the wildfire had burned more than 36,000 acres, destroyed dozens of homes and contributed to worsening air quality throughout Southern California.
Some not-so-good news: Southern California hasn’t yet entered the worst of its annual fire season. In September and October, powerful “Santa Ana” winds carry dry air from interior deserts toward the coast, further drying out already parched landscapes and raising the risk of wildfire and unhealthful air.