22.0 Human Actions and the Atmosphere

A smelly, irritating, grayish haze blankets Los Angeles in this photo. The air isn’t just dirty. It’s deadly. Or at least it can be deadly to sensitive people, such as those with asthma.

Los Angeles is just one of several cities in California that have serious air pollution problems. In fact, of the ten U.S. cities with the worst air quality, six are in California. Why is the air in California so polluted? Is it because this state has more people, cars, or factories than other places? Is something else going on? In this chapter, you’ll find out. You’ll also learn how air pollution affects people and the environment.