EPA's nitrogen oxide data tell a powerful tale and offer another example of why today often is better than the nostalgically remembered "Good Old Days." In terms of air quality, all of us are much better off today than 4 years ago and the pace of improvement is quickening.
Indeed, America is more rapidly than ever returning our air to a quality not breathed in 80 or more years. One marker of the wonderful cleaning of America's air is the decline of nitrogen oxides, a leading cause of human illness, and regulated by the Clean Air Act.
In 1970, total nitrogen oxide emissions stood at 26.8 million tons, with vehicles and electric power plants being the two top sources. From 1970 to 2000 nitrogen oxide pollution levels in this country dropped 16% or 4.3 million tons, an improvement but slow indeed.
From 2000 to 2008, nitrogen oxide pollution declined at a more rapid pace, dropping another 5.3 million tons or about 24%, in the 8-year period. By 2008 the annual nitrogen oxide emission as 17.2 million tons.
And the pace of the decline in nitrogen oxide levels hit top speed in the last 4 years. From 2008 to 2012, nitrogen oxide emissions fell another 5.5 million tons or another 32%. The total level is reported as 11.7 million tons by the EPA. All data is at: www.epa.gov/ttnchie1/trends/.
Today, power plants are no longer among the two leading sources of nitrogen oxide pollution. They have dropped to number 3. Vehicles and off-highway equipment rank 1 and 2.
All told America has cut its nitrogen oxide emissions by 15.1 million tons since 1970 or by 56%, while greatly expanding its population, cars on the road, and the amount of electricity consumed. For this important progress that benefits our health, environment, and economy, thank both the Clean Air Act and its standards and the private sector for making cleaner fuels like renewable energy and natural gas, installing pollution controls on power plants, building cleaner cars, and increasing energy efficiency.
So is the job of cleaning up our air finished? Huge progress has been made but there are still days when the air is unhealthy to breathe for many Americans. There is still too much mercury in fish. The clean up is not yet done. But we should recognize the progress made and finish the job.