Emissions of sulfur dioxide has decreased over the past 30 years but the pollutant is still dangerous for asthmatics, according to researchers.
In high enough concentrations, at about 5 to 10 parts per million, sulfur dioxide can cause a burning sensation in the eyes and coughing. The rotten egg odor of sulfur dioxide can be detected at 1 to 3 parts per million. However, an asthmatic could start to experience airway irritation and difficulty breathing with as little as 0.5 parts per million sulfur dioxide in the air, Ameredes said.
“Thus, if you were an asthmatic, it would be possible that you wouldn’t even know that there is sulfur dioxide in the air,” Ameredes said. “You’d just be having breathing difficulties and coughing, but you would not be able to detect the odor, therefore wouldn’t know why you were having that experience.”
It could also be more difficult for asthmatics to stop or control an irritation and inflammation response once it begins because of their inability to produce interleukin-10, a major anti-inflammatory cytokine, a protein released by cells, considered to be an “off-switch” that stops the inflammatory process, Ameredes said.