I can't really leave unchallenged city councillor Caroline Van Zyl's letter about the low emission zone in Oxford and particularly the effect of buses on air quality (Oxford Mail, March 10).

Yes, buses do have emissions, but they create nowhere near the problems that cars would cause if they were allowed unrestricted access to the city centre.

Ms Van Zyl says cars make little contribution to emission levels in the city centre, and of course the reason for that is that they are restricted and very few should legitimately be there.

Oxford Bus Company was cutting emissions to the absolute minimum long before air quality became such a political issue in Oxford.

In fact, an independent survey shows that we have the lowest emission fleet in the UK.

All our buses are fitted with additional emission suppression kits, and we have the highest proportion of Euro 5 engined buses in the country - 27 per cent of our fleet.

We therefore welcome a low emission zone in the centre of Oxford.

It will ensure that others come up to the mark.

Air quality and vehicle emissions are complex issues, so let's keep the debate to scientific facts.

PHILIP KIRK Managing Director Oxford Bus Company Cowley House Watlington Road Oxford