Air Pollution Can Lead to Chemical Reactions

Cliff Davidson, Thomas and Colleen Wilmot Professor of Engineering and Environmental Engineering Program Director, was interviewed for the WESA-FM (Pittsburgh) story “Why Are The Globes On The Sixteenth Street Bridge Different Colors?”

Davidson, who spent over 30 years studying air pollution at Carnegie Melon University, explained, “[We were] trying to identify what were the most important sources of pollutants that were soiling the limestone of the Cathedral.” Davidson went on to say, “Sulfur dioxide gas has a property that can react chemically with a surface like limestone. […] This particularly happens when the surface of the stone is wet, for example, right after a rainstorm, or maybe in the morning when there’s dew present.”