Lead (Pb) monitoring in Connecticut was discontinued at the end of 1996. There had been no violations of the quarterly lead (Pb) NAAQS at any site in Connecticut for many years. In 1996, the New Haven Stiles Street site had the highest Pb value in the state, with a maximum quarterly average of 0.08 µg/m3 or 5% of the NAAQS.
In 1997, none of the three sites that monitored nitrogen dioxide (NO2) experienced any violations of the NAAQS. Bridgeport and New Haven reported arithmetic means of 44% and 48% of the NAAQS. The photochemical assessment monitoring stations (PAMS) in Stafford and Westport operate during the summer season and had seasonal arithmetic means of approximately 12% and 34% of the NAAQS. The PAMS site in East Hartford operated for most of the year and had an annual mean of 36% of the NAAQS. The ten-year trend graph shows that the NO2 levels for these sites have been constant with only small year-to-year fluctuations.
In Connecticut, eleven of the twelve ozone (O3) sites reported violations of the NAAQS in 1997. In 1996, only five sites reported ozone concentrations above the NAAQS, while in 1995 eleven sites reported violations of the NAAQS. The cool, wet summer of 1996 contributed to the lower ozone levels of that year. In 1997, Groton reported the highest 1-hour second maximum value of 0.150 ppm or 125% of the NAAQS. The ten-year trend line shows a large fluctuation in the number of days above the NAAQS.
In 1997, none of the sites collecting particulate matter of less than 10 microns diameter (PM10) had any violations of the annual or 24-hour standards. The Norwalk site reported the highest 24-hour second maximum value of 65 µg/m3 or 43% of the NAAQS. The Norwalk site had an annual arithmetic mean of 62% of the NAAQS. The ten-year trend graph shows no discernable trends, except for a decrease in the concentration of PM10 at the New Haven site.
There were no violations of the annual, 24-hour, or 3-hour SO2 standards in Connecticut. The highest annual arithmetic mean, of 7 ppb or 23% of the NAAQS, was reported in Bridgeport. The lowest annual arithmetic mean, of 3 ppb or 10% of the NAAQS, was reported in Mansfield. New Haven reported the highest 24-hour second maximum of 32 ppb or 23% of the NAAQS. Overall, the ten-year SO2 graph shows decreasing trends.