Vermont is not required to measure the concentration of lead in ambient air. No measurement data are available. Vermont operates nitrogen dioxide (NO2) monitoring sites in Rutland and in Burlington. There was not any violation of the NAAQS for NO2 recorded at either site. Historical data for the past ten years (1988-1997) indicate that the annual average concentrations of NO2 have remained relatively stable. Between the years of 1988 and 1997, NO2 at the Rutland site ranged from 0.012 ppm to 0.015 ppm, and NO2 at the Burlington site ranged from 0.017 ppm to 0.019 ppm. The Burlington-Winooski Avenue monitoring site recorded the maximum 1-hour concentration of 0.060 ppm.
Neither of the two ozone monitoring sites in Vermont recorded 1-hour concentrations of ozone in excess of the NAAQS. The Bennington site reported the highest ozone concentration of 0.106 ppm. The highest recorded concentration of ozone at the Proctor Maple Research Site was 0.086 ppm. Vermont has recorded only one violation of the 1-hour ozone standard since 1988.
Vermont maintains seven monitoring sites that measure particulate matter (PM10). The Bennington site recorded the highest 24-hour concentration of 56 µg/m3. The Rutland site recorded the highest annual average (weighted) concentration of 24 µg/m3. This concentration is well below the annual average NAAQS for PM10. THe lowest recorded measurements for PM10 were recorded at the Proctor Maple Research facility monitoring site. Maximum 24-hour concentrations were at or below 38 µg/m3, and the annual weighted arithmetic mean was 13 µg/m3. Over the past ten years, all five PM10 monitoring sites in Vermont's urban area have recorded particulate matter concentrations below the annual and 24-hour NAAQS with slight downward trends. Yearly variability in the data is common, in part determined by meteorology, transport of particulate matter from distant sources, and changes in the emission of local sources.
The monitoring sites in Burlington and Rutland also measure sulfur dioxide (SO2). There were no violations of the NAAQS for sulfur dioxide recorded at either site. The highest 24-hour average concentration of SO2 (39 ppb) was recorded at the Rutland site. This site also recorded the highest 3-hour SO2 concentration of 82 ppb. In contrast, the Burlington site recorded a maximum 24-hour average concentration of 14 ppb and a 3-hour maximum concentration of 41 ppb. Ten years (1988-1997) of historical SO2 data indicate a general decline in SO2 concentrations in Burlington, but show a one year (1994) spike in SO2 concentrations in Rutland.