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Air Pollution
September 2010

Air Pollution
Residents living near the Central Corridor are concerned about exhaust from the many cars and trucks that use the Corridor every day. Air pollution is partly related to dust and exhaust from traffic. The Minnesota Pollution Control Agency (MPCA) monitors the amount of air pollution across the state, including in the Central Corridor.

The federal Clean Air Act and Amendments require all states to monitor air quality. The good news is that since 2002, air pollution in Minnesota, including the Central Corridor, has been lower than all national outdoor air quality standards. Changes in fuel, cleaner operating cars, and reduced emissions from industry have all helped reduce pollution.

Air Pollution and Health
Breathing in polluted air, especially carbon monoxide and fine particles from cars and trucks (and other sources), can make existing breathing problems such as asthma worse. Breathing in polluted air is also linked to an increased risk of death from heart attack, stroke, and cancer. Children, the elderly, and those with heart or breathing problems are the most sensitive to air pollution. Polluted air has also been linked to low birth weight in babies. These findings have lead to stricter air quality standards, resulting in more days classified as having poor air quality. MPCA issues alerts when the air quality index (AQI) reaches a level where sensitive groups (mainly children and those with heart or breathing problems) should take extra care to protect their health. Since the AQI is the main way that the MPCA informs people about air quality, the increase in alert days has led many Minnesotans to believe that air quality is getting worse, when in fact it has steadily gotten better, especially when compared to the 1960s and1970s.

What the Information Shows
To look at air pollution levels in the Central Corridor, MDH used two methods. First, we used data collected by the MPCA at four places in or near the Central Corridor. MPCA measured two air pollutants commonly associated with motor vehicles and industrial sources: carbon monoxide and fine particles [defined as Particulate Matter <10 microns in diameter (PM10) and Particulate Matter less than 2.5 microns in diameter (PM2.5)].

The first map shows the four places where carbon monoxide (CO), PM10, and PM2.5 were measured and the hourly (CO) and weekly (PM10 and PM2.5)  averages in 2004-2009. The national outdoor air quality standards are also shown for comparison. Like all of the Twin Cities, levels of these air pollutants in the Central Corridor are well below the federal standards. (Click on the map for a larger image.)

Second, to estimate how far from the heavily travelled roads traffic-related air pollution might reach, MDH used a model developed by MPCA staff that is based on traffic volume in 2008 (see second map). The model results show that, as expected, air pollution levels are lower further away from busy streets. Areas near the busiest roads (such as I-94) will likely have higher levels of traffic-related air pollution. The map also shows the total result of air pollution from traffic when there are many busy streets nearby. (Click on the map for a larger image.)

Limitations
MPCA’s outdoor air monitoring network is designed to monitor overall trends in air quality in the Twin Cities. It is also used to see if air pollution levels meet federal air quality standards under the Clean Air Act. The results from each location where pollution is measured may not be exactly true for other nearby areas. This way of measuring will not show if there is a sudden increase in air pollution for a short period of time. It still is the best way we have to measure air pollution in Minnesota. The model used to estimate traffic-related air pollution cannot be used to determine actual concentrations of air pollutants and does not consider weather or local differences in air patterns. It still is a useful tool for showing the potential impact of busy traffic on local air quality.

Printable information sheet, with maps: Air Pollution (PDF: 507KB/4 pages)

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Click on the maps below for a larger image

Map of Air Quality in the Central Corridor, 2004-2006

Map of vehicle-related air pollution based on 2008 traffic counts

Updated Friday, 05-Apr-2013 10:14:48 CDT