California has some of the most stringent air quality standards in the world, making the state a closely watched and often-mimicked trendsetter in national and international air quality and climate change circles.


But heat waves, wildfires, and other projected consequences of continued warming could unravel decades of progress in the Golden State, according to a new report by the California Air Pollution Control Officers’ Association.

To get an idea of what could be at risk in a warmer California, consider this: over the last 20 years, the state’s population has increased by 22 percent and the average daily miles driven have increased by 45 percent. Yet, over that same period statewide emissions of smog-forming pollutants have fallen by more than 50 percent.

As the climate in California continues to warm, however, another story could dominate the state’s future.

“The effects of climate change threaten to reverse … progress and diminish decades of investments made to improve air quality,” the report stated. “The higher number of extreme heat days and heat waves predicted to occur as a result of climate change will increase smog formation, increase the number and severity of wildfires, worsen heat island effects in urban areas, and increase adverse health effects due to the public’s increased exposure to harmful air pollutants.”

The winter of 2013 may have offered Californians a window into a future of poorer air quality. Last year’s winter season came during the state’s driest year on record, and it was accompanied by extended periods of stagnant air. Cold overnight temperatures coupled with unseasonably warm afternoons “created strong atmospheric inversions and poor mixing of air,” the report stated. Northern California was hit particularly hard with the resulting polluted air. Three air districts in that region endured an abnormally high number of days with concentrations of fine particulate matter (known as “PM 2.5”) exceeding national standards.

PM 2.5 are tiny particles or droplets in the air that measure about two-and-one-half microns in length. (There are about 25,000 microns in an inch.) PM 2.5 reduces visibility and generates haze when levels are elevated, and they’re most likely to be elevated when there’s little or no wind.

In 2012, the San Francisco Bay Area didn’t post a single day of exceeding the PM 2.5 national standard. In 2013, it exceeded the standard 12 days. In the Sacramento area, the number of days jumped from two to 15. In the San Joaquin Valley, the state’s breadbasket in the great Central Valley between Sacramento and Los Angeles, the number jumped from 16 to 38.

More Illnesses and Health Risks Feared

“If the winter of 2013 is an indication of future meteorological conditions that can be expected as a result of climate change most regions in the state could experience decreases in air quality that will lead to increases in air pollution related illnesses and health risks,” the report stated.

The San Joaquin Valley is particularly vulnerable to high particulate levels and high ozone. As the state’s agricultural center, its population density is low but traffic volumes are high. It’s also climatically bounded by coastal hills to the west, the high Sierra to the east and mountains to the south that separate the region from the Los Angeles Basin. Ironically, the famous Sequoia National Park in the western Sierra — above and directly east of Fresno in the Central Valley — has been known to have periods of horrendous air pollution imported from the valley below.

Another vulnerable region is the South Coast Air Basin, which includes Los Angeles and the urban sprawl that surrounds it. High population density and high traffic volumes are conspiring to set the region up for high air pollution days ahead.

As of today, however, the state’s progress has been remarkable. The Air Resources Board estimates that 63 percent of California residents live in areas that meet the federal eight-hour standard for ozone, up from 24 percent in 1990.

Meanwhile, California is on track to meet its 2020 greenhouse gas target of 1990 emission levels. But keeping emissions at 80-percent below 1990 levels by 2050 — the state’s long-term target — will be much more challenging, the report said.

Higher efficiency power plants and buildings, lowering short-lived but potent greenhouse gases such as methane, promoting more compact development that relies on public transit, increasing solar energy, and other steps are being explored by the state’s air pollution control districts.

Looking ahead, California could face more stringent federal rules for its eight-hour ozone standard. This past January, the U.S. EPA released a draft policy assessment hinting that the current standard of 75 parts per billion (ppb) may not adequately protect human health. It could be dropped to somewhere between 60 ppb and 70 ppb, although any such regulatory effort is certain to encounter political opposition and likely court challenges. As recently as 2013, 15 regions of California failed to meet the current standard of 75 ppb, which was set back in 2008.

Particulate pollution also has faced more aggressive federal rules. In 2012, the EPA reduced the PM 2.5 standard from 15 to 12 micrograms per cubic meter. The San Joaquin Valley, South Coast and Imperial County (an agricultural region east of San Diego) do not meet this 2012 standard — although all other regions of the state do meet it.

What’s the cost of poor air quality? The report begins to answer this question with a few hard numbers. Annual health costs of air pollution-related illnesses in the South Coast region total $22 billion, or $1,250 per person. In the San Joaquin Valley, the cost is $6 billion annually, or $1,600 per person.

Nationwide, EPA has estimated that meeting ambient air quality standards under the federal Clean Air Act could save $2 trillion in annual benefits by 2020.

Experts express concerns that as climate change leads to a warmer and drier California, the costs of dirtier air could place a drag on what historically has been one of the world’s largest and most vibrant economies.

Topics: Health