ScienceDaily (Aug. 9, 2009) — Burning of fossil fuels pumps chemicals into the air that react on surfaces such as buildings and roads to create photochemical smog-forming chlorine atoms, UC Irvine scientists report in a new study.

Under extreme circumstances, this previously unknown chemistry could account for up to 40 parts per billion of ozone – nearly half of California's legal limit on outdoor air pollution. This reaction is not included in computer models used to predict air pollution levels and the effectiveness of ozone control strategies that can cost billions of dollars.

Ozone can cause coughing, throat irritation, chest pain and shortness of breath. Exposure to it has been linked to asthma, bronchitis, cardiopulmonary problems and premature death.

"Realistically, this phenomenon probably accounts for much less than 40 parts per billion, but our results show it could be significant. We should be monitoring it and incorporating it into atmospheric models," said Barbara Finlayson-Pitts, Distinguished Professor of Chemistry and lead author of the study. "We still don't really understand important elements of the atmosphere's chemistry."

When fossil fuels burn, compounds called nitrogen oxides are generated. Previously, scientists believed these would be eliminated from the atmosphere upon contact with surfaces.

But UCI scientists discovered that when nitrogen oxides combine with hydrochloric acid from airborne sea salt on buildings, roads and other particles in the air, highly reactive chlorine atoms are created that speed up smog formation.

Hydrochloric acid also is found indoors in cleaning products. When it interacts with nitrogen oxides from appliances such as gas stoves, chlorine compounds form that cause unusual chemistry and contribute to corrosion indoors.

The study was undertaken by scientists involved with AirUCI, an Environmental Molecular Sciences Institute funded by the National Science Foundation. UCI's Jonathan Raff conducted experiments; Bosiljka Njegic and Benny Gerber made theoretical predictions; and Wayne Chang and Donald Dabdub did the modeling. Mark Gordon of Iowa State University also helped with theory.

Said Finlayson-Pitts: "This is a great example of how our unique collaborative group can produce some really great science."

Story Source:

Adapted from materials provided by University of California - Irvine.

enlarge

Burning of fossil fuels pumps chemicals into the air that react on surfaces such as buildings and roads to create photochemical smog-forming chlorine atoms, scientists report. Under extreme circumstances, this previously unknown chemistry could account for up to 40 parts per billion of ozone -- nearly half of California's legal limit on outdoor air pollution. (Credit: iStockphoto/Patrick Herrera)

Related Stories

Dirty Windows In Urban Areas May Be Hidden Contributors To Air Pollution (May 14, 2007) — The grime that accumulates on windows, buildings, roads, and other surfaces in urban areas could be an important source of nitrogen oxide air pollutants, scientists in Canada conclude in a new ...  > read more

Chemists Find New Important Contributor To Urban Smog (Mar. 25, 2008) — Chemists have discovered that a chemical reaction in the atmosphere above major cities long assumed to be unimportant in urban air pollution is in fact a significant contributor to urban ozone -- the ...  > read more

Scientists Find Chlorine May Contribute To Ozone Formation (June 14, 2006) — Standard methods of predicting air pollution don't take atmospheric chlorine into account, but the chemical could be responsible for 10 percent or more of daily ozone production in local air, ...  > read more

Ocean Proximity Aggravates Houston's Ozone Pollution (Mar. 25, 2009) — Increasing levels of atmospheric carbon dioxide are known to result in reduced coral calcification because carbon dioxide alters ocean chemistry and decreases aragonite saturation because it ...  > read more

Search ScienceDaily

What's In Our Air?