The L.A. Glow: Smog, Sunlight, and the City of Angels

Los Angeles is renowned for its unique light, often celebrated by artists, and filmmakers. But the source of this glow isn’t quite what many believe. While often romanticized, the distinctive quality of light in Los Angeles is largely a product of pollution, scattering sunlight and creating a diffused effect. Despite improvements in air quality, the phenomenon persists, a reminder of the city’s complex relationship with its environment.

The Allure of L.A. Light

For decades, the light of Los Angeles has captivated creatives. David Lynch, the acclaimed filmmaker, described the light as “inspiring and energizing,” noting its brightness and smoothness and the feeling that “all possibilities are available.” Lawrence Weschler, writing in the Fresh Yorker, documented how many prominent figures, including Vin Scully, “pined for” this light after leaving Southern California.

The Science Behind the Glow: It’s the Smog

However, the romantic notion of the L.A. Glow is complicated by scientific reality. Paul Wennberg, an air pollution chemistry professor at Caltech, explains that much of the effect is caused by smog. Tiny particles in the air redirect sunlight in all directions, creating a diffused glow rather than harsh shadows. “It’s all the pollution in the air that is scattering…redirecting the light from the sun,” Wennberg said. “That process, makes the air ‘glow,’ literally.”

Suzanne Paulson, director of the Center for Clean Air at UCLA, adds that this scattering effect can actually reduce the amount of direct sunlight reaching the ground, potentially by as much as 50% on some days. Clear days, like those during Santa Ana winds, reveal the stark contrast, with smog layers visible over the ocean.

A History of Air Quality in Los Angeles

The issue of air pollution in Los Angeles dates back to at least 1943, when a major smog event sparked fears of a Japanese chemical attack. This event marked the birth of photochemical smog, unique to Los Angeles. In the early 1950s, Caltech professor Arie Haagen-Smit discovered that tailpipe emissions and industrial pollutants, when baked by intense sunlight, created this specific type of smog.

The formation of the Los Angeles County Air Pollution Control District in 1954, and later the South Coast Air Quality Management District in 1977, signaled a commitment to improving air quality. Through regulations targeting consumer products, gasoline formulations, and vehicle emissions, significant progress has been made. Paulson estimates that the air is now “70, 80 percent cleaner” than it was decades ago.

What Makes L.A. Unique?

Los Angeles’s geography contributes to its pollution challenges. The surrounding mountains trap heat, while deserts bring hot winds and coastal breezes create cool air. This combination leads to an inversion layer, where pollutants become trapped near the ground.

Despite these factors, Wennberg emphasizes that the glow itself isn’t unique to Los Angeles, but the city’s romanticization of it is. He jokingly suggests a need to “build shadows great again,” highlighting the importance of clear air and direct sunlight.

Looking Ahead

While significant improvements have been made, further reductions in pollution require broader changes, such as electrifying vehicles and appliances and reducing reliance on fossil fuels. Even at current levels, pollutants pose health risks, contributing to respiratory and cardiovascular issues. The story of the L.A. Glow serves as a reminder of the complex interplay between environment, perception, and the ongoing pursuit of cleaner air.