Connecticut's Management of Toxic Air Pollutants

Monitoring Initiatives

The Department has taken a proactive and innovative approach to monitoring for toxic chemicals in the ambient air. New technologies continue to evolve where voids existed or where existing techniques were not sensitive enough to detect low levels of specific chemicals. The Department has developed the ability to monitor approximately 100 chemicals, including metals, volatile organic compounds and aldehydes. In addition to monitoring programs mandated by the EPA, the Department also conducts additional monitoring programs for air toxics at various locations throughout the state to assess air quality.  Learn more about air monitoring in Connecticut.

Toxic Air Study in Connecticut: CT DEEP conducted the Toxic Air Study in Connecticut (TASC) from 1999-2003 to provide data on ambient levels of HAPs in Connecticut. This monitoring was conducted in the immediate vicinity of six stationary sources, and one background site. Due to the short time period for these studies, no long term trends can be established, but these studies do provide the following information: formaldehyde and acetaldehyde showed increases during the summer months which were likely due to photochemistry but concentrations of these two chemicals were potentially influenced by mobile sources. In addition, formaldehyde did show occasions of point source influence.

These two compounds were monitored at levels which may be of concern, as compared to proposed limits for annual exposure from the CT DPH, although these levels were consistent with levels measured across the country. The annual HLV numbers were used for comparison since they were more conservative than the proposed one hour values. Nineteen different species of Polycyclic Aromatic Hydrocarbons (PAH) were monitored. Seasonal and spatial variability were observed in the PAH data with the more volatile species peaking in the summertime while the less volatile PAH peaked in the winter months. PAH levels were reasonably below the CT DPH’s proposed levels of concern.

Twelve metals were monitored in these studies and the metals showed spatial variation but little seasonal variation. Both lead and nickel appeared to be below the CT DPH’s proposed levels of concern while manganese was close to these proposed levels of concern, but this level was consistent with levels measured across the country. Some other metals’ detection levels were too close to the detection limit to evaluate with respect to the proposed level of concern.

Ambient concentrations of fifty-four different species of VOCs were monitored during the studies but analysis focused on eight of the most prevalent species. Spatial differences were most pronounced for toluene and methylene chloride and least for chloromethane and trichlorofluoromethane. None of the eight species showed significant seasonal variation. None of the eight VOCs analyzed were monitored at the CT DPH’s proposed levels of concern. Additional VOCs were not analyzed because they were generally below the detection level or had detection levels above the CT DPH’s proposed level of concern.

Ambient Air Monitoring Special Projects: Monitoring data has been collected from projects throughout the state. Selection of sites and the specific air toxic chemicals to be monitored are often dictated by needs identified by the Department. For example, extensive monitoring occurred at Wallingford and Hartford of chemicals of concern to the community due to odor complaints. The data collected from these sites was evaluated by the Connecticut Department of Public Health and the United States Department of Health and Human Services' Agency for Toxic Substances and Disease Registry and reports prepared.

Photochemical Assessment Monitoring: This program is a specialized monitoring program conducted in accordance with the 1990 Clean Air Act Amendments. In this program, EPA requires more extensive monitoring of ozone and its precursors in areas with persistently high ozone levels. The purpose of this program is to measure changes in levels of these pollutants. In Connecticut, ambient air monitoring sites called Photochemical Assessment Monitoring Stations (PAMS) which collect and report detailed data for various air pollutants have been established for this purpose. This network also measures meteorological information. The EPA requires the PAMS monitoring network to collect data on toxic air pollutants. Connecticut presently operates a monitoring site at East Hartford. Continued collection and analyses of these data will help the states and the EPA to better evaluate the effectiveness of control strategies and to measure environmental improvement.

Dioxin Monitoring: Another example of an ambient monitoring program administered by the Department is the ambient air dioxin monitoring program. This program began in 1987 and presently measures dioxin at one site in Connecticut. Results of the ambient monitoring program show compliance with the annual average ambient air limit of one picogram (one trillionth of a gram) per cubic meter for dioxin, as listed in Connecticut regulations. To improve the effectiveness of the dioxin sampling program, the Department has developed sampling methods to ensure its reliability and cost effectiveness.

Mercury Monitoring: The Department recognized the importance of understanding the extent of any potential mercury contamination in the environment. As such, a multi-media effort to first identify what was known about environmental mercury levels in Connecticut and secondly, to develop a plan to address the issues. A project was initiated in 1995, in conjunction with the University of Connecticut's Environmental Research Institute to determine mercury levels in fish from different lakes, ponds, the Connecticut River and Long Island Sound. A risk assessment was performed by the Connecticut Department of Public Health (CTDPH) to determine the levels of mercury in fish which are a public health concern. The results of this assessment were used in conjunction with the data gathered from this study to update a freshwater fish consumption advisory. CTDPH issued a statewide fish consumption advisory for mercury levels in freshwater fish from Connecticut water bodies in March 1996. Ongoing monitoring of mercury levels in fish is being conducted presently. A three-year ambient air monitoring project was conducted from 1996 to 1999. Eight monitoring stations have been established to measure atmospheric mercury concentrations. The network includes monitoring sites representative of both urban and rural locations and are located in Bridgeport, East Hartford, Waterbury, Cornwall, Greenwich, Groton, Madison and Voluntown. The study showed the measured ambient air mercury values were below public health concern.

Stack Monitoring: In addition to dioxin monitoring, in 1994, the Department initiated a metals testing program under which samples are collected from the stacks of municipal waste combustion facilities. The Department analyzes samples for dioxin, arsenic, beryllium, cadmium, chromium, lead, manganese, mercury, and nickel, among others. These substances are on the list of forty candidate priority air toxics for the EPA's Cumulative Exposure Project. Ten years of monitoring have revealed that all waste combustion facilities have consistently operated in compliance with Connecticut's Air Toxics Control regulation.

CT's Management of Toxic Air Pollutants | Mobile Source Programs

Content Last updated November 2005