Visible air pollution, known colloquially as “smog,” is responsible for clouding the horizons of cities all over the world. Smog forms when nitrous oxides react with sunlight, creating airborne particles which contribute to global warming and harm the health of humans, animals, and plant life. Car exhaust is one of the biggest contributors of nitrous oxide, and specific geographic and climate patterns can exacerbate the effects of the resulting smog. With approximately 14.5 million registered vehicles in the state and a climate perfect for harboring air pollution, most Californians have seen the telltale hazy skyline at some point in their life. However, thanks to California’s proactive measures, most people would be shocked to learn that the smog over Los Angeles was once so thick that it was mistaken for a chemical attack. The state has truly been a pioneer in air quality control, ensuring its citizens clean air by consistently and vigorously promoting and enforcing efforts towards reducing air pollution even before it was a federally recognized issue.
Tracey, Laura, "California’s Fight for Clean Air" (2020). Environmental Law Journal blog. 3.