According to the EPA, cars are getting cleaner and cleaner. New cars today are capable of emitting 90% less air pollution on a per-mile basis than the unregulated models of 1970, and every year they are getting "cleaner". The EPA has found that each year, the average car causes over 600 pounds of air pollution. Transportation sources (including highway and off-highway vehicles) now account for 77 percent of national total carbon monoxide emissions. Motor vehicle exhaust contributes about 60 percent of all carbon monoxide emissions nationwide. Approximately 3.8 grams of volatile organic compounds are emitted by every car every day, even when they are not driven.