|
 |
Temperature inversion is severe in the Valley of Virginia. Polluted air cannot pass because it is blocked by the Blue Ridge on the east and the Allegheny Mountains on the west. (ED SPENCER). |
As spring approaches, residents concerned about air quality know what’s ahead: murky days of summer when a haze hangs over the Valley of Virginia.
That air can pose risks for children, the elderly, asthmatics and people with heart or lung problems, according to the Centers for Disease Control. The vehicle emissions associated with it have also been connected to cancer and stroke, according to the CDC.
Ed Spencer lives at a high elevation in Rockbridge County, where, he says during the colder months he can see the distinct line where haze begins in the sky.
In winter, Spencer said, the county and the Shenandoah Valley in general hold pollution trapped by a phenomenon called a temperature inversion. Cool air pools near the ground in valley areas and leaves the air above it warmer, in contrast to the normal decrease in temperature with height.
Pollutants emitted at the ground level, such as emissions from a truck’s exhaust, float up to the cap created by the temperature inversion but cannot break through it. That causes a fog, or haze, beneath the cap.
“There’s clear air up above and cloudy air below,” said Spencer, a retired Washington and Lee professor of geology. “There’s a very sharp line.”
In the warmer months, said Spencer, a phenomenon called the Bermuda High causes air to stagnate along the East Coast. One result, in the mountain-and-valley terrain of western Virginia, is the visible haze of particulate matter, much of it from vehicle emissions along the Interstate 81 corridor. A general haze in summer months hangs over the mountains as well as lower areas.
The particulate haze isn’t the only pollution problem, however. According to the state Department of Environmental Quality, ozone is an invisible but significant component of pollution during the warmer months. According to the U.S. Environmental Protection Agency, “bad” or low-lying ozone is produced by the action of strong sunlight on hydrocarbons and nitrogen compounds from motor vehicle exhaust, industrial emissions, gasoline vapors and chemical solvents as well as natural sources.
The DEQ tests for ozone during spring, summer and fall, when warmer temperatures can cause ozone to spike to dangerous levels for at-risk parts of the population. The DEQ monitors air quality via instrumentation often equipped with nylon or Teflon filters that is set up at various locations around the state. The equipment measures levels of ozone, carbon dioxide, sulfur dioxide, nitrogen dioxide and particulate matter like dust, acids, metals and other compounds.
 |
This picture of the Shenandoah Valley was taken on a clear day without a temperature inversion. (ED SPENCER) |
A measurement called the Air Quality Index is then calculated from the
analyzed air. The AQI spectrum runs from 0 to 500, and the higher the
number, the more polluted the air.
Spencer said he thinks that reducing the human causes of air pollution is the only way to address the problem.
“There’s nothing we can do about the atmospheric conditions,” he said “It’s a lot easier to control what you’re putting into the air.”
Barbara Walsh, executive director of the Rockbridge Area Conservation Council, agrees. She said that the council has petitioned at the federal level for a railroad interstate system because using rail transportation means less fuel is burned, and fewer pollutants are released into the atmosphere.
Walsh is also a member of the Go Green Lexington Committee and has pushed for an engine idling awareness program.
The committee vice chair, John Blackburn, said that an anti-idling ordinance is being discussed in the committee.
“There are places in town where vehicles sit with engines running, like outside the elementary schools or at the hospital,” he said. “And those emissions are at face level for kids.”
Blackburn also said that on average 45,000 motor vehicles pass by Lexington every day on Interstates 64 and 81. And about 14,850 of those are trucks, creating pollution that gets trapped in the valley.
But pollution comes from outside the valley as well.
Jim Schaberl, ecologist for Shenandoah National Park, said that pollution from the Ohio Valley moves east into the area and brings with it harmful materials such as mercury.
Once this material is in the air, it makes its way into the soil and water when it rains. Acid rain and other dangerous pollutants hurt the environment, and Schaberl said he has already seen a loss of fish and invertebrate species in the park caused by mercury pollution.
Because of that, the park monitors the air 24 hours a day in order to collect information for regulation agencies, Schaberl said. Those agencies then make policy decisions that can improve air quality.
Despite these efforts, Schaberl said that conditions haven’t changed much in the past few years.
“We haven’t seen the benefit. Theoretically, things should be improving,” he said.
Produced by
Washington and Lee
journalism students.
Lead Supervisors:
Prof. Brian
Richardson
Prof. Indira Somani
Editing supervisor:
Prof. Lisa Tracy
Technical supervisor: Michael Todd