are removed by the atmosphere by two general mechanisms; reactions with OH radicals and photolysis (Wallington, et al., 1994).
Speaking as a chief guest at a day-long workshop on 'Kigali Amendment- the Way Forward', Dechen Tsering, Asia-Pacific regional director at the United Nations Environment Programme, told the participants that the ozone-depleting substances generally contain chlorine, fluorine, bromine, carbon, and hydrogen in varying proportions and are often described by the general term halocarbons
. Besides, hydrochlorofluorocarbons, chlorofluorocarbons, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components and as solvents.
According to the IPCC's report (2007): Human activities result in emissions of four long-lived GHGs: C[O.sub.2], methane (C[H.sub.4]), nitrous oxide ([N.sub.2]O) and halocarbons
(a group of gases containing fluorine, chlorine or bromine)(...) Global atmospheric concentrations of C[O.sub.2], C[H.sub.4] and [N.sub.2]O have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years (p.37).
(2009), as the impact of fluorinated halocarbons
decreases, [N.sub.2]O will likely become the dominant [O.sub.3]-depleting substance within the agricultural sector over the course of the 21st century.
His group found that noble metal nanoparticles can completely degrade halocarbons
into amorphous carbon and metal halides.
The use of contrast agents that are not gadolinium based such as fluorinated halocarbons
, deuterated water (2[H.sub.2]O) [13, 14], and 17O-water  has been investigated.
Concentration variability of halocarbons
over an electronics industrial park and its implication in compliance with the Montreal protocol.
The CO2 CH4 N2O and halocarbons
are long-lived GHS and their concentration is continuously increasing because of human activities.
Vilker, "Adsorption of low molecular weight halocarbons
by montmorillonite," Environmental Science & Technology, vol.