A ‘winning strategy’ for air quality? Better city design
Local air quality, says Brian Magi, is “a resource we should cherish and protect.” And it’s the subject of some of the more wide-ranging research he has underway. Magi is assistant professor of atmospheric sciences at UNC Charlotte in the Geography and Earth Sciences Department. He spoke about what he has learned so far about the air Mecklenburg County residents breathe. His edited remarks:
Q: What are you studying?
A: My research evolves from monitoring pollutants such as ozone and fine particulate matter to understanding how and why they vary in time and space. I am particularly interested in better understanding neighborhood-scale pollution variability.
This article is part of the KEEPING WATCH on AIR initiative.
Q: What has surprised you about your findings?
A: My research is in an exploratory phase, but I have been surprised by how much variability in air quality there is between different neighborhoods. This spatial scale is not specifically monitored or addressed by the federally mandated monitoring protocols defined by the Clean Air Act. For example, in Mecklenburg County, there are only about four to five air monitoring locations in the whole county, and really only about two to three have the full suite of pollutant monitoring. I am interested in what is happening between those monitoring sites
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Clean Air Act – The 1970 federal law regulates air emissions from stationary and mobile sources. The Environmental Protection Agency carries out the law. It sets standards for six common air pollutants: carbon monoxide, lead, nitrogen dioxide, ozone (ground-level), particulate matter and sulfur dioxide. It also oversees permits that control toxic air emissions from industrial and commercial sources.
Ozone – Ground-level ozone is formed when nitrogen oxides, such as what are emitted in vehicle exhaust, join with volatile organic compounds, also called “reactive organic gases” or “hydrocarbons.” These chemical reactions need sunlight to occur. Even relatively low levels of ozone can cause health problems. Ozone can make it harder to breathe deeply and can cause shortness of breath, coughing or a scratchy throat. It can increase the frequency of asthma attacks and continue to damage lungs even when the symptoms have disappeared. People with lung disease, children, older adults and people who are active outdoors may be particularly sensitive to ozone. Ozone can also harm sensitive vegetation during the growing season.
Ground-level ozone is considered air pollution, but ozone in the upper reaches of Earth’s atmosphere protects the planet from the sun’s harmful rays.
Particulate matter – Also called particle pollution, these particles are a mixture of solid particles and liquid droplets found in the air. Some—such as dust, soot or smoke—can be seen with the human eye. Others are so small they can only be detected with an electron microscope. Long-term exposure to particle pollution is associated with decreased lung function, chronic bronchitis and premature death. Short-term exposures (hours or days) are associated with a range of effects, including decreased lung function, increased respiratory symptoms, irregular heartbeat, heart attacks and premature deaths. Particulate matter can also affect vegetation and ecosystems.
Sources include cars, trucks, heavy equipment, construction sites, power plants, industrial facilities and forest fires.
Fine particulate matter – Particles that are 2.5 micrometers or smaller, or smaller than 1/20th the width of a human hair. Fine particles can get deep into the lungs and some may even get into the bloodstream. Unlike ozone, which is usually higher in summer, daily particulate matter can be higher or lower at any time of the year.
Q: What are the biggest pollutants in our air?
A: In Mecklenburg County, both ozone and particulate matter levels hover near the edge of levels that are unhealthy to breathe for extended periods. The violation days tend to be associated with ozone and happen most often during heat waves, but particulate matter has year-round impacts, since warmth is not necessarily required for this pollution to form.
Q: What health problems can occur from breathing unhealthy levels of ozone or particulate matter over a long period?
A: Epidemiological studies are clear: Exposure to air pollution is linked to increased incidences in many health problems, including asthma, stroke, COPD [chronic obstructive pulmonary disease] and mortality. Air pollution stresses the body. This could be from relatively short exposure to high levels of pollution, or even from long exposure to low or moderate levels of pollution. The scientifically based National Ambient Air Quality Standards define the levels that counties must meet to comply with the Clean Air Act—which is fundamentally about the right to breathe clean air.
Q: How much of this region's air quality problem is an inevitable result of the geography of the Piedmont (positioned against mountains to the west), and what do we have control over?
A: The main source of pollution in our county is from vehicular traffic. That includes cars, trucks, trains and planes. Since the population of our county is increasing, this tends to mean more cars, at the very least. To me, the problem of pollution is manageable. Urban planning that includes sustainable design could play a big role in reducing the number of cars per person.
Q: What are a few realistic steps the region could take to improve air quality?
A: Reduce the number of cars per person; maintain the tree cover Charlotte is already known for.
Trees help clean the air. A huge fraction of people live in cities. If we design cities to either encourage public transit or walking/biking paths, or discourage vehicular traffic (or both), it's a winning strategy for air quality.
Q: What do you wish more people understood about Charlotte's air quality?
A: We are fortunate to live in a country that so closely monitors pollution and enforces air quality standards. We are fortunate to live in a county with relatively good air quality.
Q: With climate change, will it be harder for us to achieve high-quality air in our city than it would have been 20 or 30 years ago?
A: In general, the changing climate will increase the number of warm days and nights, and bring more frequent stagnant weather conditions. These can exacerbate poor air quality. Population increase and vehicular emissions will have to be considered in tandem with expected changes in the average weather.