Vermont operated two ozone (O₃) monitoring sites in 2001; one at the Proctor Maple Research Facility in Underhill and the other in Bennington. The 8-hour average ozone National Ambient Air Quality Standard (NAAQS) is 0.08 parts per million (ppm) and is assessed relative to the running 3-year average of the annual 4th maximum daily maximum 8-hour average. Based on this criteria, both Underhill and Bennington are 100% of the NAAQS (0.08 ppm) for 2001; this is in compliance with the standard, which must not be exceeded. The highest 8-hour concentration of ozone in 2001, 0.093 ppm, was recorded at the Bennington site. The highest recorded 8-hour concentration of ozone at the Proctor Maple Research site was 0.082 ppm. The highest 1-hour concentration of ozone in 2001, 0.102 ppm, was recorded at the Bennington site while the highest recorded 1-hour concentration of ozone at the Proctor Maple Research Facility was 0.087 ppm.

PM_2.5

Vermont maintained five monitoring sites that sampled for particulate matter with aerodynamic diameter < 2.5 microns (PM_2.5). PM_2.5 sampling in 2001 was conducted in Barre, Bennington, Burlington, Rutland and Underhill. Vermont began PM_2.5 sampling in 1999. The annual average PM_2.5 standard is assessed relative to the three-year average of the respective annual averages. The PM_2.5 annual average NAAQS is 15 micrograms per cubic meter (µg/m³). Compliance was assessed at the four sites in which three years of sampling has been conducted (Barre, Bennington, Rutland and Underhill). Three-year averages ranged from 6.8 µg/m³ in Underhill (45% of NAAQS) to 11.3 µg/m³ in Rutland (76% of NAAQS). The Burlington assessment is incomplete since it is only a two-year average; however, that two-year average is 9.0 µg/m³ or 60% of NAAQS. The PM_2.5 24-hour average standard is assessed relative to the three-year average of the annual 98th percentile sample concentration. Given Vermont's 1-in-3 day sampling schedule, the annual 98th percentile concentration is the annual third 24-hour maximum concentration. The PM_2.5 24-hour standard is 65 µg/m³. Again, compliance was assessed at four sites and the averages ranged from 21 µg/m³ in Underhill (32% of NAAQS) to 30 µg/m³ in Rutland (46% of NAAQS). The Burlington assessment is incomplete since sampling has only been conducted for two years; however, the two-year average is 26 µg/m³ or 40% of standard.

PM₁₀

In 2001, Vermont maintained five monitoring sites that sampled for particulate matter with aerodynamic diameter < 10 microns (PM₁₀). These sites include Barre, Bennington, Burlington, Rutland and Underhill. The highest 24-hour concentration was recorded at the Barre site, which recorded a maximum 24-hour PM₁₀ concentration of 50 µg/m³. Rutland recorded the highest annual PM₁₀ average (weighted) concentration of all Vermont sites, 19 µg/m³. These concentrations are well below the former PM₁₀ annual maximum 24-hour average NAAQS of 150 µg/m³ and the PM₁₀ annual average NAAQS of 50 µg/m³. The lowest recorded PM₁₀ annual average for 2001 was recorded Proctor Maple Research facility monitoring site in Underhill (10 µg/m³). The lowest recorded maximum 24-hour concentration was recorded in Bennington (42 µg/m³). Over the past five years all five PM₁₀ monitoring sites have recorded particulate matter concentrations below the former annual and 24-hour NAAQS. Yearly variability in the data is common, in part determined by meteorology, transport of particulate matter from distant sources, and changes in the emission strength of local sources.

Carbon Monoxide

During 2001, Vermont operated one Carbon Monoxide (CO) site in Rutland. No exceedance of the NAAQS for CO was recorded. The highest 1st and 2nd maximum 8-hour concentrations of CO recorded at Rutland were 2.4 ppm and 2.2 ppm, respectively. The five-year trend line shows only small fluctuations of the second highs with levels between 24% and 37% of the 8-hour NAAQS. The Burlington CO site was not in operation in 2001; however it was in operation during the period of 1995 to 1999. The second 8-hour maximums during that time period ranged between 24% and 37% in Burlington as well. In 2001, the maximum one-hour concentration of CO recorded was 4.4 ppm.

Nitrogen Dioxide

Vermont operated one nitrogen dioxide (NO₂) monitoring site in Rutland in 2001. No exceedance of the NAAQS for NO₂ was recorded. Historical data for the most recent five years (1997-2001) indicate that the annual average concentrations of NO₂ have remained relatively stable. During this time period, the annual averages for the Rutland site ranged from 0.011 ppm to 0.013 ppm NO₂. The Burlington NO₂ site was not in operation in 2001. During the period of 1996 to 2000, the annual average NO₂ concentrations ranged from 0.017 ppm to 0.018 ppm in Burlington. The five-year annual NO₂ average trend in Burlington and Rutland ranged between 21% to 34% of the NAAQS. In 2001, the maximum one-hour concentration of NO₂ recorded was 0.053 ppm.

Sulfur Dioxide

In 2001, Vermont maintained one sulfur dioxide (SO₂) monitoring site in Rutland. No exceedance or violation of the NAAQS for sulfur dioxide was recorded. The highest 24-hour average concentration of SO₂ in Rutland in 2001 was 0.024 ppm. The highest 3-hour and 1-hour average SO₂ concentrations were 0.045 and 0.063 ppm, respectively. The annual average of 0.005 ppm in Rutland for 2001 is 17% of the NAAQS. For compliance purposes, the annual second maximum 24-hour average of 0.024 ppm is 17% of the NAAQS as well. The annual second maximum 3-hour average of 0.040 ppm is 8% of the NAAQS. Five years (1997-2001) of historical SO₂ data indicate a slight decline in SO₂ concentrations in Rutland (from 0.007 ppm annual average SO₂ in 1997 to 0.005 ppm in 2001).

Lead

Vermont is not required to measure the concentration of lead in ambient air. No measurement data are available. [Note: The Vermont Air Pollution Control Division discontinued monitoring lead concentrations in Vermont in 1989.]