Catalytic converters have decreased the amount of carbon monoxide emitted by cars dramatically since they were first introduced in the 1970s. (Chris Keating/flickr)
Jenna Ladd | May 1, 2018
A new study found that levels of two primary pollutants in the U.S. atmosphere have not been declining as rapidly during recent years as they once were.
Researchers at the National Center for Atmospheric Research (NCAR) studied satellite data and ground level measurements of two smog-forming pollutants: nitrogen oxides and carbon monoxide. Levels of these air pollutants decreased dramatically following the implementation of the Clean Air Act in the 1970s. Requirements of that act pushed automakers and energy-producers to develop new technology which curbed the emissions of these two pollutants.
The study found that concentration of these two pollutants in the atmosphere decreased by seven percent each year between 2005 and 2009. However, from 2011 through 2015, the pollutants’ levels only…
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