Ozone exposures near class I Wilderness areas in New Hampshire and Vermont

Ozone (03) is known to cause characteristic injury symptoms on a wide variety of plant species. In response to concern by Federal land managers, a comprehensive program was initiated in 1988 to assess the effects of 03 on vegetation in two Class I Wilderness areas in northcentral New Hampshire and one Class I Wilderness area in southern Vermont. To better quantify the possible risk associated with 03 exposures affecting vegetation in these Wilderness areas, hourly average 03 concentration data were characterized, using biologically based exposure indicators for a site located at Mt. Equinox, Vermont (549 m) and a site at Mt. Washington, New Hampshire (457 m). Mt. Equinox experienced more of a flat diurnal pattern than the Mt. Washington site. The higher amplitude for the Mt. Equinox diurnal patterns in comparison to the Mt. Washington site was indicative of the occurrence of higher hourly average concentrations, as well as the infrequent occurrence of hourly average concentrations below 20 ppb. The Mt. Equinox site experienced more occurrences of hourly average concentrations 80 and 100 ppb than the Mt. Washington site. Similarly, the SUM60 and W126 integrated exposure values for Mt. Equinox were greater than the values experienced at Mt. Washington. The lower-elevation Mt. Washington site experienced a greater percentage of its 03 exposure during the daylight hours (0700–1859h) than the Mt. Equinox site.