Last
year: #9
Ozone
pollution rank: #16
Cincinnati may be known as the "Queen City," but its air quality is not fit for royalty. The Cincinnati metropolitan area is consistently featured in the top 10 most particle-polluted areas. Car exhaust, boats on the Ohio River and especially power plant emissions cause most of the soot. From 1996-2003, emissions increased 83 percent at the Miami Fort plant in Hamilton County. Water pollution is also a huge issue. In 2009, the Ohio River was considered the worst toxic water dump in the U.S.