The Ministry and Environment and UNDP said Friday they would help car owners pay to have polluting air-conditioners in old cars updated.
Cars built before 1996 have air-conditioners that cool through the use of chlorofluorocarbons, or CFC, a chemical compound harmful to the atmosphere's ozone layer.
UNDP officials said Friday they would help car owners change to healthier systems, subsidizing half the cost of the upgrade.
Cambodia has 23 garages that can change the system, including 13 in Phnom Penh, for a cost of about $52.
Khieu Muth, secretary of state for the Ministry of Environment, said that the ministry has been working on the problem with UNDP.
Cambodia, which leads the region in such efforts, expects to emit no harmful CFC by 2010, he said.