Days of very unhealthy air
1
2-4
5-7
8+
2011
2012
2013
2014
2015
Seattle
Portland
San Francisco
Los Angeles
2016
2017
2018
2019
2020
Days of very unhealthy air
1
2-4
5-7
8+
2011
2012
2013
2014
2015
Seattle
Portland
San Francisco
Los Angeles
2016
2017
2018
2019
2020
Days of very unhealthy air
1
2-4
5-7
8+
2012
2013
2014
Seattle
Portland
San Francisco
Los Angeles
2015
2016
2017
2018
2019
2020
Days of very unhealthy air
1
2-4
5-7
8+
2020
2011
2012
2013
2014
2015
2016
2017
2018
2019
Seattle
Portland
San Francisco
Los Angeles