Refrigerated multibed adsorption in sampling and analysis of atmospheric light hydrocarbons at ppb (v/v) and sub-ppb (v/v) concentrations

Atmospheric pattern of volatile organochlorine compounds and hexachlorobenzene in the surroundings of a chlor-alkali plant

The outdoor atmospheric distributions of chlorinated volatile organic compounds (VOCs) from locations receiving the emissions of a chlor-alkali plant have been studied. Trichloroethylene and tetrachloroethylene (medians 2.4 μg/m³ and 1.7 μg/m³, respectively) were the most abundant compounds, which was in accordance with the production processes from these installations. The concentrations of trichlorofluoromethane, median 1.6 μg/m³, are rather similar to the average levels described in general in the troposphere and cannot be attributed to this specific source. Several by-products involving dichloroacetylene, carbon tetrachloride, hexachloroethane, hexachlorobutadiene, trans-1H-pentachloro-1,3-butadiene, 2H-pentachloro-1,3-butadiene, cis-1H-pentachloro-1,3-butadiene, tetrachloro- and trichloro-butadienes and hexachlorobenzene were also identified. Some of these compounds, e.g. carbon tetrachloride, chloroform and tetrachloroethane, could also have been manufactured during some periods. The occurrence of these manufactured compounds and by-products in the atmosphere could also reflect, at least in part, volatilization during the extraction of previously discharged chlor-alkali residues developed within the environmental restoration program of the Flix water reservoir. In this respect, the tri-, tetra- and pentachloro-1,3-butadienes could also originate from microbial transformation in the solid deposits accumulated in the water reservoir which were volatilized after extraction. Among all identified VOCs, trichloroethylene showed the highest health risks considering the measured airborne concentrations and the WHO and USEPA recommendations.

A first French assessment of population exposure to tetrachloroethylene from small dry-cleaning facilities

Used as a solvent in the dry-cleaning industry, tetrachloroethylene (C(2)Cl(4)) can be a pollutant of residential indoor air, which can cause long-term harmful exposures because of its neurotoxicity and probable carcinogenicity. In France, dry-cleaning facilities are integrated in urban environments (shopping malls, residential buildings) and can contribute to C(2)Cl(4) exposure for customers and residents. This exploratory work presents the results from five studies carried out in one shopping mall and four residential buildings housing a dry-cleaning facility. These studies involved dry-cleaning machines fitted with a Carbon Adsorber and unfitted, with or without Air Exhaust System. Samples were collected in the cleaning facilities and in the apartments located above with passive samplers allowing measurement of time-integrated concentrations on a 7 days sampling period. It has obviously shown the degradation of indoor air quality in these environments and underlined the contributing role of the machine technology and ventilation system on the amount of released C(2)Cl(4) in the indoor air. To temper these results, it must be pointed out that some parameters (building insulation, amount of solvent used...) which would influence C(2)Cl(4) fugitive release have not been quantified and should be looked at in further studies.

PRACTICAL IMPLICATIONS

In France, dry-cleaning facilities are frequently integrated in urban environments (large shopping malls or residential buildings) and can significantly contribute to tetrachloroethylene (C(2)Cl(4)) population exposure. The amount of fugitive releases in these environments depends on several parameters such as the dry-cleaning machine technology (fitted or unfitted with a carbon adsorber) and the ventilation (air exhaust system). To reduce C(2)Cl(4) exposure in residential buildings and other indoor environments with on-site dry cleaners, carbon adsorber unequipped machine should be replaced by newer technology and dry cleaners should be equipped with mechanical air exhaust systems.