10 worst in the United States and Canada

PM2.5 annual mean, micrograms per cubic metre

amount

control

Visalia-Porterville California 18

Hanford-Corcoran California 16

Portola California 16

Fresno California 15

Elkhart-Goshen Indiana 15

Regina Canada 14

Madera California 14

Lancaster Pennsylvania 13

Lebanon Pennsylvania 13

Lemhi Idaho 13

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