Air Quality in Minnesota

No city in Minnesota can compete with Los Angeles or Houston on air pollution levels. Minnesotans are unfamiliar with "ozone alerts." An ozone alert is declared by the government when pollution (ozone) in the air reaches a level that poses health risks to sensitive populations (elderly, children or anyone with compromised health). Typically, sensitive individuals are advised to stay in air-conditioned spaces.

Although the situation in Minnesota is not yet that severe, air quality problems do exist. If you look closely, you can see a brown layer of crud on the horizon around the Twin Cities. Some air pollutants are causing negative health impacts in our citizens. Others are falling out of the air and creating other concerns in our lakes and streams. This article will briefly outline some of the major air pollutants in Minnesota, including smog, fine particles, air toxics, greenhouse gases and mercury, and why we should be concerned.

Smog (also called "ground-level ozone") is created when the sun "cooks" pollution from cars, trucks and power plants in the air. The levels of smog in the Twin Cities are currently within the range allowed by law, but they're close to the limit. Even at legal levels, smog may impact human health and the environment. Ground-level ozone is linked with respiratory problems, including exacerbated asthma, and adversely affects the growth of plants.

Little bits of soot and pollution, usually referred to as "fine particles," are also a human health threat. Again, levels of fine particles do not exceed legal limits in Minnesota, but strong scientific evidence links the presence of these chemicals, even at low levels, to heart and lung disease, cancer, asthma attacks, and death. Particles are released directly into the air by coal-fired power plants, cars, and wood burning. They are also formed by chemical reactions of other pollutants in the air.

"Air toxics" refers to a broad group of chemicals released into the environment that may cause health problems for people. The sources and effects of these chemicals vary widely, although the largest source of many of these chemicals is motor vehicles. Most people are exposed to a wide variety of these pollutants every day. The levels of these pollutants are mainly below health-based guidelines, but the cumulative impacts of many chemicals on the body are not well understood by scientists. In addition, the health effects of mixtures are unclear.

Greenhouse gases, pollution that contributes to global warming by trapping heat in the Earth's atmosphere, are mainly released into the air by the burning of fossil fuels. Fossil fuels are natural gas, oil and coal. The main culprits are coal combustion for electricity and gasoline burning for transportation. Carbon dioxide, the main greenhouse gas, is not toxic to people (we exhale it when we breathe), but global warming does pose several possible threats to Minnesotans. A warmer climate would change the character of our forests and wildlife, possibly reducing the populations of walleye and other cold-water fish. Tropical diseases also will begin to move north, such as the West Nile virus that recently appeared in the Northeast. It is important to note that the science showing that human activity is influencing the global climate is strong. Due to atmospheric complexities, predicting the exact effects of global warming on specific regions is difficult, but we do know that we are making an impact.

The imposingly titled "persistent, bioaccumulative toxics" are perhaps the scariest of the air pollutants. The term "persistent" means these pollutants are not naturally destroyed in the environment. "Bioaccumulative" means that the chemical "builds up" in the food chain. For example, a small microorganism may eat one of these chemicals. Then a fish eats many microorganisms, exposing itself to more of the chemicals. Then a person (or an eagle, otter, etc.) eats several fish and the pollutants build up in the person. Many of these chemicals fall out of the air and land in water or soil. Mercury, dioxin and many pesticides are examples of this class of pollutants. Health impacts include cancer, neurological and reproductive effects and developmental problems. These chemicals are especially problematic because the health effect may occur to the offspring of those people exposed, making it difficult to determine the cause. Sources of these chemicals include pesticides, waste incineration and coal burning.

What is the link between the different pollutants? Many are created and released during energy production or, more specifically, fossil fuel combustion. The cars we drive and the coal we burn for electricity create many of these problems. Other pollutants are fossil fuel-derived, including pesticides and materials used to make plastics. We can all reduce the emissions of these chemicals (and our own exposure) by reducing the amount of fuel we burn.

Overall, Minnesota's air quality is similar to most other places in the United States. We enjoy lower levels of smog and some air toxics, but similar levels of many other pollutants. Greenhouse gases, fine particles and persistent chemicals are not Minnesota-specific problems. Air pollution should be a concern, however, and Minnesotans should do what they can to reduce their contribution and exposure when possible.