Air pollution is the world’s single biggest health risk. But while the U.S. has cut nitrogen oxide (NOx) emissions in half since 1990, air pollution is actually worse in many parts of the country. The cause? Emissions across the Pacific.
The expanding car cultures of China and India are having a noticeable impact on air quality in the U.S., according to a new study published in the scientific journal Atmospheric Chemistry and Physics. Roughly 1,400 new vehicles are hitting the streets every day in New Delhi, and all that NOx is reacting with other chemicals in the atmosphere to form ozone that’s eventually blown west into California, Colorado, and other western U.S. states—especially in the spring when winds are strongest.
"Smog pollution is a global problem," said Meiyun Lin, a Princeton University researcher and lead author of the study, in an interview with Co.Exist. "A global perspective is necessary when designing a strategy to meet U.S. ozone air quality objectives."