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Clean air and transportation


From Barb Thoman, Executive Director

The air in Minnesota is cleaner than it was 40 years ago, when cars without catalytic converters burned leaded gasoline and industry smokestacks had fewer controls. Yet, over that same period, we’ve also found out more about how air pollution affects people’s health and the environment.  In short, we’ve found that lower levels of air pollution affect our health more than we had previously thought.

Based on this new knowledge, the Environmental Protection Agency (EPA) has tightened federal air quality standards for lead, nitrogen dioxide, ozone, small particles, and sulfur dioxide in recent years.  Even more stringent standards are now proposed for ozone and small particles. 

Why are elevated levels of ozone and small particles in our air of such concern that stronger regulation is necessary? Because ozone and fine particles contribute to many health problems.

  • OZONE. The health effects from elevated concentrations of ozone include “breathing problems, lung tissue damage, and premature mortality” (California Air Resources Board). Even persons who are otherwise healthy may experience health effects when ozone levels increase.  A recent study also shows that ozone contributes to cardiovascular events like heart attacks.  (Minnesota Pollution Control Agency,
  • FINE PARTICLES. These particles enter the deep lung and are transferred into the bloodstream where they can travel to and affect other organs.  Fine particles have been shown to increase heart disease, respiratory disease, lung damage, cancer, and mortality. They also make asthma worse and lead to increased hospitalizations and deaths. People with respiratory or heart disease, the elderly and children are the groups most at risk. Fine particles are also major contributors to reduced visibility (haze). (California Air Resources Board, and Minnesota Pollution Control Agency,,_Fine_(PM2.5)).  

Currently in Minnesota, our air pollution levels fall within EPA standards. But if, as expected, the standards become more stringent, we’re likely to exceed the new limits and be “out of compliance” with the Clean Air Act. Non-compliance would trigger a mandatory multi-year planning process and implementation of programs and actions to reduce pollutants. Exactly what will be required depends on the specific sources of pollution.  The costs of nonattainment would spread throughout the economy and could be very large. 

There are many sources of harmful air pollutants, including factories, homes, and other places where fuel and wood are burned, as well as farms where crop and livestock dust are generated. Vehicle tailpipe emissions contribute significantly to the creation of ground-level ozone and diesel emissions along interstate highways contribute to elevated levels of particles adjacent to those corridors.



Our transportation system and our personal transportation choices can either be part of the problem or part of the solution. Shifting trips from driving to transit, walking, or bicycling could play an important role in protecting air quality by reducing vehicle tailpipe emissions.


According to US EPA, a single passenger car emits nearly one pound of carbon dioxide per mile driven. Transit saves space on the road and emits a fraction of the pollution of driving alone.


Transit emits just a fraction of the air pollution of driving alone. More bicycling and walking also reduces emissions. We know this first hand from the combined efforts of TLC’s Bike Walk Twin Cities non-motorized transportation pilot program and the Volpe Center at the US Department of Transportation.

Since 2007, our BWTC program has been measuring the rate of bicycling and walking in the Twin Cities. Using the data from 2010, which showed bicycling up 33% since 2007 and walking up 18%, USDOT calculated the impacts on levels of driving and emissions. The results: in 2010 alone, more than 7 million miles were covered on bike or foot rather than in a car. From 2007-2010, more than 14 million miles shifted from driving to bicycling and walking.

And what’s the impact of less driving on air quality. Here is the chart from Volpe, showing that every day in the Minneapolis area, more bike/walk trips and less driving meant less carbon monoxide, nitrogen oxides, particulate matter and hydrocarbons.

USDOT Volpe Center CONVERSIONS for Minneapolis-area pilot.
Based on 7,260,877 averted vehicle miles travelled (VMT) in 2010
and 14,521,754 averted VMT for 2007-2010.


Other transportation options that can protect air quality by reducing tailpipe emissions include increasing use of car and bicycle sharing, telework and telecommuting programs, van pooling and carpooling.

So, what’s next with air quality issues in the Twin Cities? The Minnesota Pollution Control Agency manages compliance with the federal Clean Air Act in Minnesota. Currently, the MPCA is collaborating with the Minnesota Environmental Initiative, a nonprofit organization, to oversee an 18-month study process, called the Clean Air Dialogue, to identify options to reduce air emissions and reduce the risk of falling out of compliance with new air standards.

Transit for Livable Communities is one of the invited participants in the Clean Air Dialogue. If our region commits to building out our transit system (bus and rail) and keeps working to make bicycling and walking safe and convenient options across the metro, we can show how emissions from transportation can be reduced – contributing to cleaner air and better health.

For more information on:

The Clean Air Dialogue process

Bike Walk Twin Cities Count report

Non-Motorized Pilot Program report to Congress



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With our latest bus purchases, 69% of the MetroTransit bus fleet will meet even the most stringent EPA emission standards (and the rest of the fleet is almost as clean).

Such a good and interesting blog to read on. Our transportation development has great impact on our environment.

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