Although cities like Mumbai, London, Beijing and Paris substantially differ from each other, they do share a common problem: pollution. Some comes from farming, mining or other sources of particle emissions in the region, but all cities have transport as one major source of pollution in common. Particles are emitted through brakes, tyres, clutches and from larger particles being ground to smaller size between tyres and road surface. The single largest contributor to particles in the air of an urban region are soot particles released from diesel engines.

Diesel particles at the same time have been classed as an official cause of lung cancer by the World Health Organisation (WHO). Increasing concern about the cancer-causing potential of diesel exhaust had led to evaluation of further studies conducted on mine workers. The risk for those exposed to diesel exhausts was significantly higher than with their peers. The International Agency for Research on Cancer (IARC) Working Group had concluded that there is sufficient evidence in humans for the carcinogenicity of diesel exhaust making it an official cause of lung cancer. The same group had previously classed diesel exhausts as probably carcinogenic to humans (Group 2A) in 1988 and had recommended the re-evaluation of the classification with high priority since 1998.

Following these findings, the responsible decision makers are struggling to find solutions for their cities. More and more cities are looking to restrict the use of private vehciles inside the city relegating private individuals to public transport.

London Mayor Boris Johnson had already thought out aloud on further restricting traffic in the congestion zone. Even restriction for cabs and buses seem possible as even streets banning private vehicles exhibit elevated levels of pollutants. Paris Mayor Anne Hidalgo is presenting similar ideas following last year’s banned entry of diesel vehicles due to elevated levels of winter smog.

While the experts discuss different possible solutions, it becomes evident that reducing the emissions inside the cities should be the highest priority. There might even not be one single solution to meet all requirements, it might rather be a mix of different options. Different options among which we find Autogas for light duty vehicles (taxis and delivery vans) and even possibly more refined versions of LPG-diesel dual fuel systems