By Mark Wert, January 5, 2014
AIRQUALITYMONITOR-LOCAL: Wednesday December 18, 2013: The air pollution measurement station just west of interstate I-75 south of the I-74 interchange in Camp Washington.
What you don’t know about the exhaust-laden air surrounding the nation’s highways could make you sick.
With nearly 1 in every 7 Americans – 48 million people – living within 300 feet of a major highway, airport or railroad, the consequences of heavy traffic on the nation’s health could be staggering.
It’s why local regulators are targeting one of Cincinnati’s busiest expressways for answers.
Cars and other vehicles are major contributors to air pollution along Interstate 75 and other major highways across America. In the past, regulators deliberately disregarded the air in “near-road” environments because the data there is so heavily influenced by emissions from the concentrated number of vehicles. That data has become more important, though, after a number of recent scientific studies associated health problems with proximity to roads.
The Southwest Ohio Air Quality Agency was charged with placing a new air sampling station adjacent to an expressway under recently tightened federal monitoring standards for oxides of nitrogen, a type of emission that’s a precursor to ozone or smog pollution.
If you’ve driven on Interstate 75 just south of I-74 recently, you may have seen the station on the edge of I-75’s west side, the first such station in Ohio.
Growing scientific evidence shows a strong association between highway pollutants and acute cardiovascular events, said Douglas Dockery, a professor with the Harvard School of Public Health, in an interview last year with InsideEPA.com, an online news service covering the regulator.
“Roadway proximity studies are also reporting associations with other unexpected health outcomes” that need to be studied, said Dockery, a member of a key scientific panel that advises the U.S. Environmental Protection Agency on air pollution.
Tougher environmental regulations often bring complaints about restrictions on business and job losses. But it’s uncertain what kind of pollution curbs could follow the new monitoring since it will take several years to collect enough national data, and any rules would have to account for how buildings alter and add complexity to the urban environment.
A 2012 study of air pollution in Las Vegas underscored the second point. In the journal Atmospheric Environment, EPA researchers reported higher pollution levels along ground-level expressways compared to those elevated over or cut into the ground. In addition, pollution levels were higher near the downwind end of bridges. The study concluded that new considerations might be needed in future highway designs, including examining how construction changes near highways affect how pollutants move away from roads.
All metropolitan areas with at least 1 million people have to add the new roadside monitors. In Kentucky, regulators plan to place a near-road monitoring station in the Louisville area, according to documents filed by the state Energy and Environment Cabinet’s Division for Air Quality.
The new Ohio station, paid for with a $200,000 grant from the U.S. EPA, is housed in a metal shed with a large antenna that looks like it might be a spy agency’s listening post. The antenna actually is there to monitor weather conditions. The instruments inside the building, which sits at the end of Colerain Avenue in Camp Washington, came to life Wednesday. The data is available in real time on the air agency’s website, www.southwestohioair.org.
Smog-making nitrogen oxides, particulates get top scrutinyWhat officials at the air quality agency, part of the Hamilton County Department of Environmental Services, will be watching most carefully are levels of two of our region’s most common air pollutants: oxides of nitrogen and particulates.
Nitrogen oxides are a problem because in the summertime they combine with another type of pollutant, volatile organic compounds from such sources as gasoline, to create smog or ozone pollution. Smog typically is a summertime concern because the two pollutants need heat and ultraviolet rays – two things in short supply in the Tristate’s three other seasons – to be converted into ground-level ozone.
Ozone pollution causes structural damage to the lungs and lowers resistance to respiratory infections. On days with high ozone levels, both young and old people are warned to stay inside. Ozone also causes other problems, such as inhibiting plant growth, dulling car paint and making rubber and plastic products brittle.
The U.S. EPA says our region’s two biggest sources of nitrogen oxides are vehicles (which contribute about 45 percent of such pollutants) and power plants and factories (which contribute about 53 percent). In addition, nitrogen dioxide also causes acid rain.
Particulates, sometimes called soot or black carbon, are microscopic bits released in the exhaust from trucks, buses and cars, as well as from smokestacks and wood-burning stoves. They can cause asthma, heart attacks and strokes and have been linked to thousands of deaths nationwide each year.
Soot levels locally have been falling in recent years. In early December, though, state regulators told federal EPA officials that Hamilton, Butler and Clermont counties don’t meet recently tightened federal standards for the tiniest kind of soot – particles no bigger than 2.5 micrometers in diameter. Warren County’s air, however, now meets the standard after years of failing to do so, Ohio officials believe.
How small are 2.5 micrometer particles? Two thousand of them fit in the length of a paper clip. That’s the problem: They are so tiny they can lodge deeply in human lungs and even enter the bloodstream.
In addition to particulates and nitrogen oxides, the new station also will report carbon monoxide levels.
Makeup of traffic on I-75 determines station's siteThe role of expressways in boosting a neighborhood’s “background” pollution was underscored in an air pollution study published earlier this year by a researcher at Cincinnati Children’s Hospital Medical Center and three other community organizations. The study was designed to pinpoint whether idling buses boosted air pollution around schools, focusing on four Cincinnati Public Schools elementary schools. The background pollution level was highest at Hays-Porter, which sits less than a quarter mile east of I-75 in the West End, the researchers found.
The Camp Washington station’s site was selected based on a number of factors including average daily traffic count, truck traffic, congestion patterns, fleet mix (since different vehicles use different fuels) and population. The agency already had monitors at 17 other locations in Hamilton, Butler, Clermont and Warren counties. The site needed to be in Hamilton County because of the large number of commuters from surrounding counties.
“Some preliminary evidence shows urban populations with increased vehicle miles traveled may result in peak exposure concentrations occurring on and near major roadways,” said Anna Kelley, monitoring supervisor for the agency. “That’s why this new air monitoring program is so important.” ⬛