Or was it the particle emission that troubled everyone?
EU legislation defines the standards in the areas of noise, particle emissions and safety.
The rule would also reduce fine particle emissions by 29 percent by 2015.
The authors noted that particle emissions varied substantially even among the same model of machine.
Quality of surface water in the south of China was improving and particle emissions were stable.
"Still lots of particle emissions from the node," Berg said.
It is already clear enough, however, that the health detriments of fine particle emissions are severe and pervasive.
Zero-sulphur fuel reduces particle emissions from these older vehicles too.
I believe these vehicles must be required to use clean fuel, too, if we want to cut particle emissions.
If traffic continues to grow as it has been doing over the past few years, particle emissions will increase as well.