The science behind LA's beloved sunlight. (Hint: It's the smog)

Happy Daylight Saving, when time is bent so mere mortals can have more time to play in the sunshine.

It's a reminder of how much we treat the sun as an inalienable right here in L.A., as we emerge from months of long nights when darkness descends at the inconvenient hour of, say, 4:30 p.m.

For artists, filmmakers, writers, the light of Los Angeles has been a source of inspiration.

The late David Lynch was an avowed fan. He wrote about its transformative quality in his 2006 book of musings and reflections, "Catching the Big Fish: Meditation, Consciousness, and Creativity."

"The light is inspiring and energizing. Even with smog, there’s something about that light that’s not harsh, but bright and smooth. It fills me with the feeling that all possibilities are available. I don’t know why. It’s different from the light in other places," Lynch recounted.

That same L.A. glow was memorialized in the New Yorker three decades ago by writer Lawrence Weschler, who chopped it up with a constellation of notable names in the arts, sciences and beyond — including the great Vin Scully — about the light that the writer "pined for every day" since leaving Southern California.

Actually, it's pollution

All this sweet talk rankles  Paul Wennberg, who teaches air pollution chemistry at Caltech. He and his research team have worked to reduce pollution in cities across Asia, Mexico and the U.S.

 "They're waxing poetic about the L.A. glow," he said. "A lot of it is caused by smog."

L.A. glow

Wennberg is not talking about the glorious magic hour sunsets, but the gentle sunlight we've come to associate with Los Angeles.

The kind of light that doesn't produce harsh, defined shadows. And why not? Because of the many tiny particles of smog in the air that are perfectly sized to ricochet light in all conceivable directions.

"It's all the pollution in the air that is scattering, as we say, redirecting the light from the sun," he said.

That process, Wennberg said, makes the air "glow, literally."

Lynch’s "bright and smooth."

"This is why artists say they like Los Angeles — it's because the light comes at us from all directions," he said.

And on really polluted days, Wennberg continued, the sky looks overcast. "It keeps us from having shadows."

That means we're actually getting less sunlight, says Suzanne Paulson, director of the Center for Clean Air and a professor at UCLA.

" It varies obviously from day to day, but it can be easily half the sunlight that is actually not reaching the ground because of the pollution," Paulson said.

The drastic difference on a non-polluted day — with its full direct sun casting hard shadows — can be seen on clear days, like during the Santa Anas.

Those winds can be “so strong that they come and basically scour out the whole basin and push all the smog off the coast," Paulson said. "And sometimes you can see this smog layer out over the ocean."

Even as the L.A. light continues its glow, both Wennberg and Paulson said the bad air we experience here in 2026 is nothing like what it was in decades past — thanks to the pioneering work done by the state and the city.

'L.A. smog'

The first major Los Angeles smog event happened July 26, 1943, and caused panic among the populace who feared the ominous dark haze was a Japanese chemical attack.

In essence, that was the birth of photochemical smog, often known as L.A. smog, distinct from other serious episodes that had happened in the winter elsewhere.

But how it was different chemically wasn't known until the early 1950s, when Caltech professor Arie Haagen-Smit discovered that certain tailpipe pollutants along with industrial emissions get baked by intense sunlight — and result in L.A. smog.

By then, the Los Angeles County Air Pollution Control District was formed, the first in the nation. It was merged with similar entities in Orange, Riverside and San Bernardino counties to create the South Coast Air Quality Management District in 1977.

"The air quality was horrendous," Paulson said.

But through hundreds of laws, from those regulating consumer products like lighter fluid or oil paint, to requiring reformulated gasoline and catalytic converters for cars, the air has become dramatically healthier.

"Over the years in California, we have really led the world and made what has been a crowning achievement," she said. " The air is 70, 80% cleaner than it was."

So much has been done, she said, that regulations have just about reached their limits.

"We've done all the easy things, and it's just really hard to find additional things that we can regulate to improve the air quality," she said.

Bigger changes — for example, electrifying more vehicles and appliances, and burning less fossil fuel — will be needed to curb pollution further. Because even at reduced levels, pollutants are still harmful, leading to not just respiratory illnesses but cardiovascular issues and environmental degradation.

Are we special?

So is the L.A. light unique?

Los Angeles's geological features — our mountains that trap heat, deserts that produce hot winds and coasts that create cool sea breezes — all contribute to pollution being held close to ground in a process known as inversion, Paulson and Wennberg noted.

And the stuff just sits there, stubbornly shrouding the city until the winds come to chase it away.

But no, the glow in L.A. isn't special, said Wennberg at Caltech, but our romanticization of it is. And if you are ever curious if pollution is around, he said just look at the ground.

" You'll see a shadow, but it'll be much less sharp," he said.  "When I see the really bad pollution here, it still makes me very sad. I think we need to, you know, make shadows great again."