California is less polluted than it was decades ago, but the last 10 years show only modest, uneven improvement in smog—especially in the Los Angeles basin. South Coast Air Basin days exceeding the 0.070 ppm 8-hour ozone standard fell from 132 in 2016 to 108 in 2025. Peak levels are lower than in the 1980s–2000s, yet LA-Long Beach remains the nation’s worst ozone metro area, and early 2026 was smoggier than recent years due to heat. PM2.5 has declined more clearly (about 34% in central LA from 2014–2024).

Both cleaner gasoline cars and EVs contributed. Newer ICE vehicles emit far less NOx, VOC, and PM per mile because of tighter LEV/Tier 3 rules, better catalysts, and fleet turnover. Diesel truck rules produced large cuts. Those changes explain most of the on-road drop so far. EVs add a real but still smaller increment: they were a tiny share of the fleet in 2016 and reached roughly 5–7% of light-duty vehicles by 2025. A 2019–2023 satellite study found that adding 200 ZEVs in a California neighborhood was associated with a 1.1% drop in annual NO2. Modeling shows ozone and PM benefits that grow with electrification and are largest around LA. Because EVs have zero tailpipe emissions, the effect is genuine even at current modest fleet share.

Newsom is not accurate that the only effect of scaling back federal fuel-economy standards is a smoggier USA. The rollback (roughly 50.4 mpg to 34.5 mpg fleet average by 2031) is projected to increase gasoline use by about 96–100 billion gallons through 2050. That extra fuel burned raises tailpipe and refinery emissions of NOx, VOC, and PM—the precursors to ozone and soot—so air quality would be somewhat worse than under the prior trajectory. NHTSA and comment analyses also project hundreds of additional premature deaths from those criteria pollutants. That part of the tweet is directionally correct.

It is not the only effect. Official analyses also project lower new-vehicle prices (roughly $900 per vehicle in NHTSA’s figures), more manufacturer and buyer flexibility (less pressure toward EVs or smaller cars), and higher long-term fuel spending by drivers. Separate EPA actions on greenhouse-gas standards add more emission increases, but criteria-pollutant tailpipe standards themselves were not repealed. The result is a modest worsening of air quality relative to the prior rules, not a return to 1970s-style smog. In California specifically, most recent gains came from cleaner conventional vehicles and diesel rules; EVs have helped but have not been the dominant driver yet. Newsom’s framing treats one real cost as the sole outcome and ignores the trade-offs.

So, the FACTS say he is too one-dimensional in his thinking. 

And while we're fact checking, what has HE ACTUALLY done to make life MORE affordable?

VERDICT: MOSTLY CRAP.

Discuss.

Gas prices are at near-record highs and Trump’s response is to force you to get fewer miles out of every tank of gas.

Make America Smoggy Again.

Sponsored by Big Oil. https://t.co/WtgkOLhlbm

— Gavin Newsom (@GavinNewsom) September 27, 2026