Scientists are now looking at a little-known pollutant that has big implications for Colorado air quality

Juracement Cement Factory in Wildegg, Switzerland. 30 May 2006. Author: Stefan Wernli

Scientists at the National Oceanic and Atmospheric Administration launched a study Tuesday to test nitryl chloride levels in the Front Range’s atmosphere. 

This little known pollutant originates from salts, and was therefore thought to be most common near the ocean’s salty waters. 

But in 2008, large quantities of the compound were discovered by accident in the air above Boulder.  Scientists were testing instruments built to measure nitryl chloride when they found that levels here were comparable to those on the coasts. 

The concentration is particularly high in the winter, when there is less mixing in the atmosphere. 

Nitryl chloride forms at night, when pollutants from vehicles and power plants combine with chlorine in the air. 

In the morning, the sun hits the nitryl chloride and breaks it down.  This kickstarts a chain reaction that eventually produces smog and greenhouse gases like ozone and methane.  Nitryl chloride is therefore thought to be an important precursor to climate change.    

A 1,000-foot tower, built for weather studies in the 70’s, will now serve as the home base for a month-long study of this pollutant.  Thirty researchers will take turns spending the night on top of the tower, kept company by more than a ton of testing equipment.