Minnesota’s air quality is generally good and has been improving for most pollutants. Minnesota has been in compliance with all national ambient air quality standards since 2002. Also, concentrations of most toxic air pollutants of concern have gradually decreased until, individually, they are below levels of health concern. Much of this decline can be attributed to lowered emissions from major facilities and cleaner cars and fuels due to enforcement of the Clean Air Act and Clean Air Act Amendments, as well as voluntary reductions undertaken at some facilities.
However, even as air programs have contributed to the decrease in emissions and concentrations of many air pollutants, increased understanding of serious health effects has resulted in stricter national ambient air quality standards. In 2006, the daily fine particle national standard was lowered by nearly half. In early 2008, the ozone standard was lowered from 0.08 parts per million (ppm) to 0.075 ppm. In October 2008, the quarterly lead standard was made 10 times stricter than the previous standard.
As a result, even as emissions and concentrations of key pollutants have decreased, the number of poor air quality days has increased. Air Pollution Health Alerts are called when the air is expected to be unhealthy for sensitive groups or higher according to the air quality index (AQI). These days are almost always the result of high levels of fine particles or ozone. Since the AQI is a main communication tool for Minnesota air quality, the increase in alert days leads to a dichotomy in public perception, with many Minnesotans believing that air quality is worsening, when in fact improvements are being made.
In 1970, the United States began seriously dealing with air pollution through the Clean Air Act. This commitment was reinforced when the Act was amended in 1977 and 1990. The Clean Air Act Amendments required issuance of technology-based standards for major sources and certain smaller non-point sources. It also paved the way for cleaner vehicles and vehicle fuels.
Since the enactment of the Clean Air Act and Clean Air Act Amendments, concentrations of traditional air pollutants have generally decreased. However, as scientists learn more about the health effects of these pollutants, standards have also become stricter resulting in more air alert days.
As the understanding of air pollution continues to evolve, new methods of environmental protection must be explored. It is increasingly obvious that it is not enough to control single pollutants from individual sources. There is growing recognition of the need to reduce air pollution emissions from scattered, less regulated sources such as transportation and residential burning.
In addition, climate change is an on-going challenge that is expected to have significant health and ecological costs. A more holistic view that includes tools such as conservation, efficiency and cleaner technologies — as well as traditional regulatory tools — will be needed to continue to improve Minnesota’s air resources.