Modesto, CA
- High ozone days per year: 33
- No. of days with unhealthy particle pollution: 16
- People with asthma: 40,719
- Population: 547,899
Out of the most polluted cities in the United States, Modesto is among the six areas with the highest number of unhealthy particle pollution days (four of the others are also in California and one in Alaska).
The Central Valley, which is surrounded by mountains that trap the area’s pollution in the valley, is home to eight of the most polluted cities nationwide.
