America's air isn't getting cleaner as fast as it used to
DENVER (AP) " For decades America's air was getting cleaner as levels of a key smog ingredient steadily dropped. That changed about seven years ago when pollution reductions leveled off, a new study found.This means when tighter federal air quality standards go into effect later this year, many more cities may find themselves on the dirty air list.There are several reasons for the flattening of nitrogen oxide levels including hard-to-reduce industrial and truck pollution, said [...]
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