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Monitoring Ozone for Air Quality Standards
Ground-level ozone is an important air pollutant in Pennsylvania. Ozone forms in the summer when nitrogen oxides (NOx), emitted from burning fossil fuels, and volatile organic compounds (VOCs) combine and react in the presence of sunlight and warm temperatures.
National ambient air quality standards (NAAQS) for ground-level ozone are established by the U.S. EPA and each state must develop a plan describing how it will attain and maintain the NAAQS.
Data from projects run by Dennis Decouteau, professor of horticulture and plant ecosystem health in the Department of Horticulture, and Donald Davis, professor of plant pathology in the Department of Plant Pathology, furnish data to the Pennsylvania Department of Environmental Protection (PADEP) for use in evaluating and setting National Ambient Air Quality Standards for ozone and other photochemical oxidants.
Their research has three main objectives: 1) monitor ground-level, tropospheric ambient ozone in rural parts of Pennsylvania; 2) conduct studies regarding biological effects of ozone on sensitive plants; and 3) conduct educational efforts regarding adverse effects of ground-level ozone on vegetation.
The Air Quality Learning and Demonstration Center (“Air Quality Center”) in the Arboretum at Penn State is used to demonstrate effects of ozone on vegetation through environmental education.
Most air quality monitoring stations are sited within urban centers, but through cooperative efforts with the PADEP’s Bureau of Air Quality, six ozone monitoring stations are sited in the more remote and forested areas of central Pennsylvania. In addition, ozone exposures are being monitored with passive devices at numerous additional sites. On broadleaf species, foliar injury is exhibited as a stipple and/or more general pigmentation of the upper leaf surface late in the growing season. These symptoms are considered to be the best response parameter to observe and relate to ambient ozone exposures. Several broadleaf plant species are known as bioindicators of ozone exposures; symptom observations in central Pennsylvania confirm black cherry, yellow-poplar, white ash, common milkweed, spreading dogbane and blackberry to be sensitive to ambient ozone exposures.