29 July 2009.
For immediate release.

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Press Release

Cars ARE cleaner than buses
2009 report finds that, per passenger km travelled, cars emit less toxic pollutants than buses
A Transport and Travel Research Ltd (TTR) report published in March 2009 1 2 suggests that, on an average per passenger kilometre travelled basis, bus travel appears to have been more polluting in terms of toxic emissions than car travel over the last 10 years.
Key findings: TTR's expectation that Particulate emission reductions from bus exhausts will improve faster than those from cars seems optimistic given that Particulate filters are now being fitted in diesel car exhaust systems and Euro V emissions regulations are imminent.
Cars are also catching up with buses in terms of emissions of the much demonised non-pollutant Carbon Dioxide (CO₂). Small diesel cars and petrol hybrids emit less CO₂ per passenger km than buses.
The report makes clear the "importance of modernising the bus fleet if the bus is to be promoted as a reduced pollution option compared to the car" and "increasing the passenger loading can only go so far if older buses are kept in the fleet." No mention is made of the respirable carcinogens 1,8-DNP and 3-NBA that are emitted when large diesel engines, such as those fitted in buses, are under load. 3
ABD Environment spokesman Paul Biggs said:
“This report confirms that travelling by car is 'greener' than travelling by bus. Bus companies will have to invest heavily in fleet modernisation and the retrofitting of emission abatement technology to even stand a chance of keeping up with increasingly cleaner cars. This is a 'wake up' call to politicians who persist with the transport and environmental mantras of 'the answer's a bus, now what's the question?' Given that buses and coaches carry only 6.3% of passengers compared to the 86.5% who travel by car, van or taxi 4, should 6% of passengers be given up to 50% of the road via bus lanes? Furthermore, bus companies that have failed to retrofit emission abatement technology to older vehicles should be held to account.”


1. Reducing emissions from PTE/SPT bus fleets - study report by TTR
2. Presentation: Scenarios and Opportunities for Reducing Greenhouse Gases and Pollutant Emissions from Bus Fleets in PTE/SPT Areas
3. Exhaust emissions from large diesel engines have been shown to contain the two most carcinogenic chemicals known to science, 3-nitrobenzanthrone (3-NBA) (Dr Hitomi Suzuki, University of Kyoto) and 1,8-dinitropyrene. In standard Ames tests of carcinogenicity, where only 0.0000003 grammes of these pollutants caused 6 and 5 million mutations respectively These genotoxins are far worse than the banned food colouring Sudan 1, which gave a positive Ames test 'only in isolated cases' and 'negative results in the HGPRT, UDS and chromosomal aberration tests' (Federal Institute for Risk Assessment). In other recent tests, 3-NBA was found to cause DNA migration in human liver cancer and lung cancer cells. The research report concluded (V H Mersch-Sundermann et al, 2003) that 3-NBA is a genotoxic carcinogen.
4. Road Users Alliance - Road File 2008/9 [pdf]
Notes for Editors about the ABD