Air Quality Trends - SO2Air quality trends are used to assess if the air quality is improving and thereby determine if control and abatement strategies are effective.
EPA strengthened the primary National Ambient Air Quality Standard NAAQS) for SO2 on June 2, 2010. The revised primary SO2 standard is a new 1-hour standard at a level of 75 parts per billion (ppb). EPA’s evaluation of the scientific information and the risks posed by breathing SO2 indicate that this new 1-hour standard will protect public health by reducing people’s exposure to high short-term concentrations of SO2. The following chart shows that monitored 1-hour design values* in Connecticut have been below this standard since the year 2000.
*To attain this standard, the 3-year average of the 99th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 75 ppb.
Content last updated March 25, 2021