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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

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Administrative data

Link to relevant study record(s)

Description of key information

The hydroxy radical atmospheric half-life is estimated to be approximately one year.

Key value for chemical safety assessment

Additional information

According to Atkinson (1989) and SRC AOPWIN (2009) the half life of chloromethane is 360 d and 310 d, respectively. According to SIDS (2004) the exact pathway for decomposition in the troposphere is not known; however, the ultimate degradation products would be HCL, CO and CO2 (Spence et al., 1976; Singh et al., 1982). The direct photolysis of chloromethane appears unimportant in the troposphere (Shold and Rebbert, 1978). Most of the HCl produced by tropospheric degradation of chloromethane will be removed via precipitation. HCl formed in the stratosphere probably plays some role in regulating stratospheric ozone, but the extent to which HCl is an active species; a temporary sink or permanent sink for chlorine is still being debated. A small amount of chloromethane may be removed with precipitation in the form of rain and/or snow, although this is not likely to be a significant atmospheric process. The stratospheric steady-state ozone depletion potential (ODP) of chloromethane has been determined to be 0.02 relative to CFC 11 (ODP=1) (Solomon et al., 1992; WMO, 1994; Fabian et al., 1996). The contribution of industrial chloromethane to the Global Warming is of no relevance since the current industrial emission rates of chloromethane is too low to contribute meaningfully to atmospheric greenhouse heating effects (Grossman et al., 1997). Greater than 99% of ambient air concentrations of chloromethane originate from natural sources (US EPA Toxic Release Inventory (TRI), 1998; SIDS 2004), primarily from the ocean (Fabian, 1986; Rasmussen et al., 1982; Singh et al., 1979; Yung et al., 1975).