Monitored Asbestos Concentrations in Connecticut

Abstract

An air asbestos survey was conducted between late 1974 and early 1977 to define the magnitude of the health hazard posed by airborne asbestos fibers in Connecticut prior to the promulgation of the State's proposed asbestos air quality standard (i.e., 30 ƞg/m³ or 30,000 total asbestos fibers/m³, 30-day average). A newly developed low volume particulate sampler, which operates continuously for 30 days at an air sampling flow rate of 4 cfm, equipped with special membrane filters was used to collect ambient TSP samples for subsequent chrysotile asbestos electron microscopic determination by the Bat-telle-Columbus Laboratories and Walter C. McCrone Associates.

Approximately 40 monitoring sites were selected; ambient locations included "typical" urban sites removed from known stationary sources of asbestos emissions, rural-background sites, stations contiguous to 4 industrial users of asbestos (i.e., manufacturers of friction products, insulated wire and cable, ammunition and molding compounds), 3 toll plazas situated at various points along Interstate 95 and indoors at a swimming pool at the University of Connecticut (the ceiling over the pool was sprayed with an asbestos-containing insulating material). Ambient chrysotile asbestos levels removed from asbestos emission sources in both urban and rural locations were below 10 ƞg/m³. However, asbestos concentrations above 30 ƞg/m³ were measured near each of the industrial users of asbestos. Furthermore, asbestos levels adjacent to the toll plazas were also elevated (in the 10 ƞg/m³ to 25 ƞg/m³ range), implicating asbestos emissions from vehicle braking lining decomposition as a significant source of airborne asbestos fibers. Indoor air asbestos levels were below 1 ƞg/m³ suggesting that the risk to public health associated with the deterioration of asbestos surface coatings applied indoors may not be as severe as previously thought.