Sir – Your correspondents last week missed the predominant argument in favour of a tram system in Oxford — improving air quality.

The air quality in Oxford now is so bad as to undoubtedly be responsible for many deaths, and many children suffering asthma who would not otherwise.

Diesel particulate emissions contain carcinogenic “volatile organic compounds” like benzene which penetrate deep into the lungs. NOX emission is known to ‘exacerbate’ asthma, but there is mounting evidence that it causes it, especially in children. (In the US, the national average child incidence is nine per cent, whereas in Elementary schools near busy roads it rises to 24 per cent, for example.) I myself suffer asthma when I ride my bike in town, unless I wear a very expensive mask.

With current affordable technology, only a tram system could substitute electric traction for the diesel engine. Power can now be delivered without unsightly overhead wires.

There are other advantages to the tram, especially for a city like Oxford.

A light electric system would remove the hideous noise buses create. Trams are typically narrower, substituting length for width, and can thus navigate narrow streets while leaving room for cyclists and pedestrians. They are much more energy efficient and would reduce carbon emission. Lastly, they are much more compatible with bikes than are buses, since their path is constant and free of the constant need to pull in and out.

While a tram system has high upfront cost, it can repay investment over a very long period. (The state has in the past offered finance for which OCC failed to apply.) In any case, the cost of the diesel bus is arguably higher; it’s just met in the currency of life, health, and the quality of our urban environment.

Ian East, Islip