10. Salt Lake City-Provo-Orem, UT
> Average high ozone days per year: 21.8
> Average 24-hour unhealthy particle pollution: 8.0
> Adults with asthma: 206,440
> Population: 2,672,368
9. Sacramento-Roseville, CA
> Average high ozone days per year: 23.5
> Average 24-hour unhealthy particle pollution: 21.2
> Adults with asthma: 193,091
> Population: 2,650,900
8. Houston-The Woodlands, TX
> Average high ozone days per year: 24.4
> Average 24-hour unhealthy particle pollution: 2.3
> Adults with asthma: 405,973
> Population: 7,340,823
7. Denver-Aurora, CO
> Average high ozone days per year: 27.7
> Average 24-hour unhealthy particle pollution: 6.3
> Adults with asthma: 274,959
> Population: 3,652,385
6. San Diego-Chula Vista-Carlsbad, CA
> Average high ozone days per year: 29.3
> Average 24-hour unhealthy particle pollution: 12.0
> Adults with asthma: 246,524
> Population: 3,332,427
