When microbeads were brought to the public’s attention nationally as an unnecessary environmental toxin, it didn’t take much time for us to get legislation moving and to pressure manufacturers to phase out their use. Those tiny, shiny bits of plastic, used as a kind of exfoliant in personal care products, are visible.

My theory is that because we can see them, and understood how water creatures in our food chain swallow them, we took swift action. What is less visible – but just as impactful – are the chemicals in the air we breathe.

The Minnesota Pollution Control Agency (MPCA) measures our air quality index for five major pollutants, getting data that offers perspective on how our health might be affected. But if we could see the particles in the air, perhaps it would be easier to modify our usage of certain chemicals.

The particles in the air are colorless, sometimes odorless – and only occasionally have a “taste” sense, when breathing them in makes us sick. The Star Tribune reported in Summer 2015 that 2,000 people in the Twin Cities die each year because of air pollution.

Following is an overview of toxins in the air we breathe, and where they come from, based on MPCA Air Quality reports presented to the Minnesota State Legislature every two years, and a Minneapolis Air Quality Study done in Winter 2008, as funded by the City of Minneapolis Department of Regulatory Services. All information and images are from Minnesota Pollution Control Agency reports.

Assessing Risk

We tend to get nervous about air quality when we smell pollution from a chemical plant – as sometimes happens, for example, in Northeast Minneapolis – or see a plume of smoke coming off an incinerator. Yet it is generally not one pollutant, from one source, that causes the most risk. It is the combination of multiple sources of pollutants.

Although urban air quality is generally good, levels of fine particles and other pollutants are elevated in the Twin Cities metropolitan area and other Minnesota cities, compared to most of Greater Minnesota.

Climate change has the potential to increase pollution reactions, because of the heat-trapping greenhouse gas, carbon monoxide, that remains in the atmosphere for long periods of time.

Significant Contributors to Air Pollution

• Electricity produced from burning coal
• Vehicles – cars, trucks, and buses
• Off-road vehicles – construction and agricultural, yard and garden, recreational, trains, planes, and boats
• Residential wood burning for heat or recreation, and residential garbage burning
• Dry cleaners, gasoline filling stations, woodstoves, painting/solvent use, auto body shops, bakeries

The majority of the air pollutants of most concern today come from smaller, widespread sources that are not regulated in the way power plants and factories are. Mobile sources, residential wood burning and residential garbage burning contribute nearly 75 percent of air pollution emissions in the state.

• Point sources — industrial and manufacturing buildings, such as power plants, refineries, waste incinerators, which are traditionally regulated. According to emissions data, these sources contribute just over 25% of overall emissions of regulated air pollutants in Minnesota.
• Mobile sources — gasoline and diesel combustion in cars, trucks, buses, tractor trailers, trains, plans, lawnmowers, snowmobiles and construction equipment. Trucks that idle to warm the engines and pressurize brakes, especially on cold days, are a big factor in some neighborhoods.

Fine particle pollution also comes from compounds created when sulfur dioxide (SO2) and nitrogen oxides (NOX) react with ammonia in the atmosphere.

• Coal burning, primarily at power plants, is the major source of SO2.
• Coal burning and mobile sources are the major sources of NOX.
• Fertilizers and livestock are important sources of ammonia.

Which Pollutants Cause Health Problems?

There are hundreds of chemicals in Minnesota’s air – often migrating into the food chain — that can cause serious health problems. These “air toxics” have no federal ambient air standards, partly because they interact in complex ways. Formaldehyde, for example, is a volatile organic compound (VOC) we tend to know is dangerous, and it contributes to ozone pollution especially during summer months. [See related article here.]

Deeper Definitions

Ozone: a colorless gas. In the upper atmosphere, it helps protect the earth from the sun’s ultraviolet radiation, but at ground level it can be harmful. It is created largely from the combination of highly reactive gases (NOX) – mostly emitted by burning fuel – and VOCs from cars and factories mixing in the presence of sunlight. The ozone level depends on the amount and ratio of VOCs and NOX in the air, as well as weather conditions, including sunlight, temperature, and wind speed and direction. As global climate change impacts temperatures, keeping ozone levels at a safer level will likely require further reductions. Minnesota, with its variable weather patterns, puts our state at risk of surpassing EPA standards.

Fine particles (aka PM2.5, as particles less than 2.5 microns in diameter): “a complex mixture of extremely small particles and liquid droplets made up of a number of components, including acids, organic chemicals, metals, and soil or dust. These particles are released into the environment when coal, gasoline, diesel, wood and other fuels are burned, and are also created in the air by chemical reactions among other pollutants.”

Hazardous air pollutants (HAPs): chemicals that cause cancer and other serious health and environmental problems. Hazardous air pollutants are a concern in urban areas because of the variety of sources that can emit them.

Volatile organic compounds (VOCs): Volatile means that they easily evaporate at room temperature and normal atmospheric pressure.

Benzene: a hazardous air pollutant, because it may cause cancer or other health problems, and a volatile organic compound, because it easily turns into a vapor and gets into the air. It is a colorless liquid with a sweet odor that dissolves slightly in water. It is highly flammable. Benzene is widely used in the United States; it ranks in the top 20 chemicals for production volume. Some industries use benzene to make other chemicals, which in turn are used to make plastics, resins, and nylon and synthetic fibers. Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, drugs and pesticides. Natural sources of benzene include volcanoes and forest fires. Benzene is also part of crude oil, gasoline and cigarette smoke.

Wood smoke:unhealthy because it contains many chemicals and compounds, which can lead to both short-term and long-term health effects. Chemicals and particles from wood smoke can irritate eyes, noses and throats, can exacerbate asthma, and are associated with increased respiratory symptoms. Exposure to wood smoke may increase susceptibility to infectious lung disease and, at high doses, may permanently damage lung tissue. Young children as well as people with asthma and other chronic lung diseases are particularly susceptible to the adverse effects of wood smoke. Solid fuels such as wood tend to have more impurities, causing them to emit more pollutants than liquid or gaseous fuels. Dry, seasoned wood—whether in a campfire or wood stove— produces far less smoke than unseasoned wood. Wood may take six or more months to properly dry.

Residential garbage burning: Today’s garbage is a mix of plastics and other man-made products that release cancer-causing pollutants and other toxic materials. Even seemingly harmless items like white office paper, junk mail, and pizza boxes give off toxic smoke.

Mercury in fish: The MPCA has determined that virtually all of the mercury in Minnesota’s surface water was deposited from the atmosphere. The level of atmospheric mercury from man-made sources must be reduced by 93% from the 1990 baseline. The goal is to reduce mercury emitted from all Minnesota sources, and help reduce fish contamination.

Specific Minneapolis Air Testing

Ten years ago, the air quality at specific Minneapolis locations was tested during 72-hour periods in May, August, October, and January, and reported in this Minneapolis air quality study.

“The results show that overall, the air quality in Minneapolis is good. However, in certain conditions, some chemicals may exceed the level where they are considered reasonably safe in the air. Of the 31 chemicals in the study, two exceeded a safe benchmark of inhalation in various locations: benzene and tetrachloroethylene.”

• In all test periods, four testing locations exceeded the lower end of the inhalation benchmark: 46th Street and Interstate 35W, 46th Street and First Avenue South, 46th Street and Nicollet Avenue South (these three are about a block from each other), and 34th Street and Cedar Avenue South.
• October tends to be a volatile month, because of relatively still air quality that enables pollutants to stay in the area longer and be absorbed at higher rates. That month in 2006, 35 locations exceeded the benzene benchmark, with many of the 31 chemicals showing higher levels. In May and August, four of the 55 locations were higher than the lower benchmark.
• The locations that exceeded the benchmark more than once were mostly at busy intersections, indicating that traffic exhaust likely contributed to the result. Other benzene sources include gasoline stations and cigarette smoke.

How Is the MPCA Being Proactive?

• Since 2006, more than 3,000 eligible school buses in Minnesota have been retrofitted with emission reduction devices.
• MPCA has worked to reduce idling emissions from long-haul trucks, retrofit publicly-owned heavy-duty trucks (particularly in the construction industry) in the metro area, and implement emission-reducing technologies in heavy-duty diesel fleets.
• Retrofitted 40 Metropolitan Airport Commission airport support vehicles.
• Replaced old engines in five 100-ton cranes operating on Twin Cities metro bridge projects.
• Funded six new delivery trucks, used for Twin Cities-area deliveries, into electric-diesel hybrids.
• In response to widespread mercury contamination of sport fish, MPCA developed a statewide mercury Total Maximum Daily Load (TMDL).
• Worked with the University of Minnesota, local funeral directors, and the Department of Health to reduce mercury emissions at crematoria.
• Reinvigorated outreach to salvage-yard operators to build awareness of the environmental problems that mercury wastes can create.
• Provided leadership for the Drive Electric Minnesota partnership, to encourage the use of clean, renewable energy and zero air emissions for vehicles. A partnership led to installation of more than 50 plug-in charging stations.
• Helped establish the Green Building Program to advance sustainable building practices in Minnesota. These practices go beyond a building‘s footprint to include the building’s location, the upstream and downstream energy consumption of water supply and treatment, and the embodied energy of materials.
• Helped place Minnesota Green Corps individuals with local governments, non-profits, universities and schools, to work on focused environmental projects.

Related Resources

• Air Quality Index for Minnesota based on daily data
• Minneapolis air quality study with data, maps and analysis (2008)
• How the MPCA is butting heads with state legislators (MinnPost, 2015)
• Chemical-free pool opens in North Minneapolis

The interconnected topics of chemicals, waste, air quality, soil contaminants and building emissions are the focal points of our Sustainable We forums #1, 2, 3 and 4. Learn more here.