Air pollution statistics for Knox Co, Ohio
3. Select a year
| Year | Percentage days with good air | Percentage days with moderate air | Percentage days with unhealthy air for sensitive groups | Percentage days with unhealthy air |
| 1997 | 84.65% | 13.49% | 1.40% | 0.47% |
| 1998 | 81.86% | 13.95% | 4.19% | 0.00% |
| 1999 | 74.88% | 20.93% | 3.72% | 0.47% |
| 2000 | 85.12% | 12.09% | 2.33% | 0.47% |
| 2001 | 78.14% | 18.14% | 3.72% | 0.00% |
| 2002 | 75.23% | 17.29% | 7.48% | 0.00% |
| 2003 | 88.37% | 10.23% | 0.93% | 0.47% |
| 2004 | 89.25% | 10.75% | 0.00% | 0.00% |
| 2005 | 81.86% | 17.21% | 0.93% | 0.00% |
| 2006 | 90.23% | 9.30% | 0.47% | 0.00% |
| 2007 | 79.35% | 20.65% | 0.00% | 0.00% |