Despite a three-fold increase in people and cars in the last 50 years, California's strict vehicle emissions standards have managed to significantly clear the state's air, according to new research.
The study also found that Southern California's air chemistry has changed for the better. The amount of organic nitrates in the atmosphere — which cause smog's eye-stinging irritation — has drastically fallen off, according to federal researchers.
Ozone and other pollutants have been monitored in the state since the 1960s. Since then the population in Southern California has tripled, as has the number of cars on the road. Nevertheless, tailpipe emissions have decreased.