A cleaner country
Air quality in the United States has im-
proved dramatically since the Clean Air Act was passed in 1970. Concentrations of PM2.5 (hazardous fine particles with diameters under 2.5 micrometers) have decreased broadly, thanks largely to regulations adopted under the landmark law.
PM2.5 air pollution concentration,
estimated (micrograms per cubic meter)
0
12.1
35.5
Good
Moderate
Unhealthy
for sensitive
groups
1981
(average: 24.0* micrograms/m3)
High: 39
Los Angeles
2016
(average: 7.5* micrograms/m3)
High: 12
Los Angeles
RYAN MORRIS, NGM STAFF
* POPULATION-WEIGHTED. LONG-TERM ESTIMATES NOT AVAILABLE FOR ALASKA AND HAWAII. SOURCES: JUN MENG, DEPARTMENT OF PHYSICS AND ATMOSPHERIC SCIENCE, DALHOUSIE UNIVERSITY; CHI LI; RANDALL V. MARTIN; AARON VAN DONKELAAR; PERRY HYSTAD; MICHAEL BRAUER
A cleaner country
Air quality in the United States has improved dramatically since the Clean Air Act was passed in 1970. Concentrations of PM2.5 (hazardous fine particles with diameters under 2.5 micrometers) have decreased broadly, thanks largely to regulations adopted under the landmark law.
PM2.5 air pollution concentration, estimated
(micrograms per cubic meter)
0
12.1
35.5
Good
Moderate
Unhealthy
for sensitive
groups
1981
(average: 24.0* micrograms/m3)
High: 39
Los Angeles
2016
(average: 7.5* micrograms/m3)
High: 12
Los Angeles
RYAN MORRIS, NGM STAFF
* POPULATION-WEIGHTED. LONG-TERM ESTIMATES NOT AVAILABLE FOR ALASKA AND HAWAII. SOURCES: JUN MENG, DEPARTMENT OF PHYSICS AND ATMOSPHERIC SCIENCE, DALHOUSIE UNIVERSITY; CHI LI; RANDALL V. MARTIN; AARON VAN DONKELAAR; PERRY HYSTAD; MICHAEL BRAUER