“Decreased sperm motility is associated with air pollution in Salt Lake City,” by Hammoud A., Carrell DT, et al.,was published in 2009 by the American Society for Reproductive Medicine and can be accessed via ScienceDirect.com.
Both semen analysis and sperm parameters data obtained from men presenting for multiple inseminations over time showed that air pollution is associated with reduced sperm motility two to three month[s] after exposure.