The Huangpu health agency called for mandatory air quality standards in buses over the weekend after it found high levels of carbon dioxide in air-conditioned buses.
The Huangpu District Health Supervision Agency said its investigation, over three seasons last year, found the average level of carbon dioxide was higher in air-conditioned buses than those without cooling systems. This suggests air-conditioned buses have less fresh air.
A team carried out tests on 71 downtown bus routes last summer, spring and winter. The buses tested each carried 60 to 70 people.
The level of carbon dioxide is the best indicator of air quality, said the team.
People exhale carbon dioxide and it accumulates because there's no sufficient outlet in the closed environment of air-conditioned buses.
The investigation also found higher level of ozone in air-conditioned buses, also suggesting the air is less healthy, the team said.
(Shanghai Daily June 15, 2009)