Table : Names, abbreviations, sum formulas, PubChem compound identifies (CIDs), boiling points Tb (at ambient pressure) and vapor pressures pvap (at 293 K) of chlorinated ethenes and, for comparison, ethene. Thermophysical properties were taken from the GESTIS property database. It is established that various health hazards are associated with airborne CEs, even at relatively low levels. In addition to acute toxicity at high concentrations, long-term exposure may have negative health consequences. For example, VC has been reported to cause liver damage, nerve damage, and immunological dysfunction, moreover, it is known to be a human carcinogen. Whereas data regarding toxicity and mutagenicity/carcinogenicity of DCE isomers are relatively sparse, it is established that TCE can cause both acute and chronic toxic effects, it has also been classified as carcinogenic. For PCE, neurotoxic effects caused by long-term exposure are most concerning, and carcinogenic effects are suspected. Due to these negative health impacts, limits for the workplace exposure to airborne CEs have been introduced in many countries. For example, Directive 2019/130 of the European Union sets the acceptable long-term exposure limits (reference timeframe: 8 hours) for VC and TCE to 1 and 10 parts per million (ppm) by volume, respectively. In Australia, long-term exposure limits are 5 ppm for VC and 1,1-DCE, 10 ppm for TCE, 50 ppm for PCE, and 200 ppm for 1,2-DCE. Indoor air pollution by CEs is of most significance in facilities where these compounds are produced and/or used (e.g., production plants, dry cleaners, etc.), although outgassing of CEcontaining products may also play a role. Besides, the pollution of different environmental compartments by CEs has raised concern with regard to potential negative effects on human health and the environment. The main sources of VC in the environment are emissions and effluents from plastic industries, with hazardous waste sites and natural gas extraction sites making additional contributions. In addition to these point sources, there have been a number of large-scale VC spills, 6 the most notorious recent example being the derailment of a freight train transporting VC, among other hazardous chemicals, in East Palestine, Ohio (USA) in February 2023. Due to its high vapor pressure, most of the VC released to water or soils will volatilize quickly. In air, it degrades photochemically within a few days. While being of less concern due to their smaller production volumes, the DCE isomers have release pathways and environmental behavior similar to VC, with reductive dehalogenation of TCE and PCE to (mostly) cis-1,2-DCE being an additional source of DCE in the environment. TCE is primarily released into the atmosphere by evaporation from degreasing operations and other industrial uses, resulting in higher atmospheric TCE levels in industrial areas as compared to rural regions. Although it mostly volatilizes from water and soils, it may also enter subsurface areas, where it is relatively persistent. The most significant release of PCE arises from fugitive emissions of the dry cleaning industry, with emissions related to degreasing and other solvent uses also playing a role. Due to its long atmospheric half-life of several months, PCE has been detected in remote locations, far away from emission sources. Disposal of PCEcontaminated sludges and filters contributes to the pollution of soil and groundwater, where it is very persistent. Both TCE and PCE have been classified as "emerging outdoor airborne pollutants" in a recent survey that aimed to identify pollutants of particular importance for better monitoring and future policy development. Among a total of 262 emerging pollutants, TCE and PCE were proposed for the second-highest prioritization category, behind only acrylonitrile and 1,3-butadiene (and having the same priority as toluene and arsenic).