Common air pollutants react and make more pollution.
http://www.environmentalhealthnews.org/ehs/newscience/common-air-pollutants-react-to-create-more/
Raff, JD, B Njegic, WL Chang, MS Gordon, D Dabdub, RB Gerber and BJ Finlayson-Pitts. 2009.
Chlorine activation indoors and outdoors via surface-mediated reactions of nitrogen oxides with hydrogen chloride.
Proceedings of the National Academy of Sciences doi:10.1073/pnas.0904195106.
http://www.environmentalhealthnews.org/ehs/newscience/common-air-pollutants-react-to-create-more/
Raff, JD, B Njegic, WL Chang, MS Gordon, D Dabdub, RB Gerber and BJ Finlayson-Pitts. 2009.
Chlorine activation indoors and outdoors via surface-mediated reactions of nitrogen oxides with hydrogen chloride.
Proceedings of the National Academy of Sciences doi:10.1073/pnas.0904195106.
Synopsis by David Buchwalter, Ph.D.
Scientists explore how common air pollutants can combine to cause worse air problems that carry severe health risks.
Common air pollutants can react with one another to form highly reactive and toxic chlorine gasses, reports a study published online in the Proceedings of the National Academy of Sciences. The pollutants – gaseous hydrochloric acid (HCl) and oxides of nitrogen (NOx) – can be abundant in both indoor and outdoor air.
The authors warn that these reactions may contribute to poor indoor air quality.
Gaseous HCl is produced both naturally and by human activities such as combustion (including burning garbage, medical wastes, coal) and some industrial processes. Gaseous nitrogen oxides are also ubiquitous as a result of combustion.
Nitrogen oxides can attach to surfaces in a process called adsorption. Lead author JD Raff and colleagues found that adsorped nitroge oxides can react with gaseous HCl to form nitrosyl chloride (ClNO) and nitryl chloride (ClNO2) – two intermediates that can react with light to create highly responsive chlorine atoms. Chlorine gas was among the first gases used in wartime in WWII, and it is a strong lung irritant and oxidant.
However, the extent of the problem remains unknown because analytical techniques to measure ClNO at low levels – parts per thousand – have not been developed. Furthermore, it is possible that similar chemical reactions may also occur with other compounds that contain bromine.
The findings are important for at least two reasons. First, the adsorption of NOx to surfaces is generally regarded positively, as it is thought to permanently remove it from air. This study shows that NOx on surfaces can, instead, be a first step in a process that creates more air pollution.
Secondly, in areas where both NOx and HCl concentrations are generally high (such as urban coastal areas – because HCl can be generated from sea salt), these chemical reactions can increase ozone pollution. Ozone is a greenhouse gas and a strong pollutant. It can affect health by irritating the respiratory system, permanently damaging lungs and aggravagting asthma.
