An Environment Ministry panel has come up with a plan that would force auto makers to reduce the diesel particulate matter their vehicles spew by up to 85 percent and nitrogen oxide emissions by 50 percent.
The reductions would be begin with cars that go on sale in the fall of 2005.
The ministry said the standards would be even stricter than those in Europe, where diesel-powered vehicles face tight regulations.
The proposals will be part of a package of revisions to the air pollution control law regarding automobile emissions. The package will be compiled by a special committee, perhaps by April.
Under the plan, trucks and buses over 3.5 tons must not emit more than 0.027 gram of particulate matter, a suspected carcinogen, per kilometer, down from the 0.18 gram under short-term regulations to be applied in October. The limit would be 2 grams, down from 3.38 grams, for nitrogen oxide, which causes respiratory organ ailments.
For small vehicles up to 1.25 tons, the limit would be 0.013 gram of particulate matter, down from 0.052 gram, and 0.14 gram of nitrogen oxide, down from 0.28 gram.
Overall, particulate matter would be cut by 75 percent to 85 percent, while nitrogen oxide would be cut by 41 percent to 50 percent.