Smog is synonymous with Los Angeles. For many lifelong locals, it’s difficult to picture the rocky edges of the San Fernando Valley without also remembering the eerie, brown-tinted haze that hangs over the city on bad air days. The problem is not isolated to Los Angeles, either; smog has become increasingly problematic in the Bay Area as well . After the devastating wildfires that raged across the Golden State this year, smoke and airborne irritants have added to the air quality problem. In many regions, it’s not uncommon to see gray ash falling apocalyptically like snowflakes from the sky.
While LA’s air quality has fluctuated in recent years, the problem stretches back decades. So, how did it start? Has it gotten better? And what, if anything, is being done to improve the air quality in LA?
Out of Thin Air
LA’s smog problem dates back to 1943, when local scientists were puzzled by the brown haze that began hovering over the Valley. Crops withered in the discolored air, and many people’s eyes were so irritated that they began wearing gas masks around Los Angeles. The US was still fighting in World War II when smog first appeared, leading many to fear that the discolored air choking out the city was a chemical attack from the Axis powers. However, it was quickly realized that this was a new phenomenon altogether.
Smog, a portmanteau of smoke and fog, can form in one of two ways. Industrial smog forms when factory smoke and sulfur dioxide mix in the atmosphere. The other type of smog, called photochemical smog, forms when nitrogen oxide molecules and volatile organic compounds interact with ultraviolet sunlight in the atmosphere. Photochemical smog is frequently caused by emissions from fossil fuels and forest fires, and this type of smog also produces secondary chemicals like ozone, which can be toxic at high concentrations.
In cooler climates, the air above a city continues to circulate, which helps reduce how much smog accumulates over an urban area. But in warm or sunny weather, smog inhibits normal vertical air circulation. This problem is exacerbated when smog pools over valleys or around hills and mountains.
The climate, topography, and huge population of motorists across Southern California help explain why this region—and Los Angeles in particular—is so prone to smog. Downtown LA is located in a deep basin, bound by the Pacific Ocean and ringed by steep hills and mountains. The valleys to the north and east of the city are also surrounded by higher elevations, making the entire region a perfect sink for smog.
Recognizing the Risks
The connection between auto emissions and smog was first realized in 1952 by a Caltech professor. By 1956, nearly 95% of doctors in LA County recognized smog as a health risk—this at a time when the medical community still debated the health risks of smoking tobacco .
Not much changed over the ensuing decades until LA was chosen to host the 1984 Olympic Games, leading many to fear that the heavy smog would ruin the event . Facing a public image crisis, the state began a series of emission-reduction programs in the 1970s that continued through the late 1980s. State legislators urged commuters to carpool or use public transit. California also required businesses to practice stricter air quality controls and urged auto manufacturers to make more efficient vehicles that produced fewer emissions.
These auto regulations were highly effective. Modern vehicles emit roughly 1% of the carbon monoxide and airborne hydrocarbons that vehicles produced 50 years ago. Even though more Californians are driving greater distances, air pollution caused by auto emissions has decreased statewide by over 85% since the 1970s, with LA, in particular, experiencing nearly a 70% decrease during that same period.
These initiatives targeting the auto industry and overall traffic emissions were an important step forward: a 1996 study on air quality found that diesel emissions accounted for a staggering 70% of cancer-causing airborne particulates.
Air Quality Today
While LA’s air quality has improved since the 70s, there’s still much to be done. A 2005 study found that air pollution-related illnesses across California were three times higher than the statewide homicide rate.
The smog problem flared up again earlier this year. During the summer of 2018, the city of Los Angeles went almost three months without a single day of quantifiably clean air. During that time, smog exceeded federal safety levels for 87 consecutive days, making this past summer the worst stretch of continuously bad air LA has experienced in almost two decades.
The American Lung Association releases an annual State of the Air report, which details the worst air quality across the country. This year’s report ranked Los Angeles as the number one worst city for ozone levels, the fourth worst city for year-round particulate pollution, and the seventh worst city for short-term particle pollution.
Planning for the Future
California has some of the strictest emissions regulations in the country, but all that could change under the Trump administration. In December 2018, the Environmental Protection Agency under this administration proposed plans to roll back Obama-era regulations on industrial coal emissions nationwide.
The administration has also recommended halting nationwide emissions and fuel efficiency standards for all new automobiles, with a specific provision that would prevent the state of California from enacting emissions requirements that are stricter than the proposed federal standards.
The city of Los Angeles has stated that its target goal is to continue reducing emissions until there are almost no days of smog by the year 2031. But with federal officials threatening to challenge California on federal- and state-level issues, it remains to be seen whether LA will meet its goal in the coming years or whether air quality will deteriorate further.