Will Bath’s Clean Air Plan restore Air Quality?

The Bath Clean Air Zone (CAZ) came into force on 15 March.  Prior to the lockdown, nitrogen dioxide (NO₂) levels were beginning to show some sign of reducing, but were well above the legal limit in parts of the centre, London Road and elsewhere. The CAZ is a welcome step towards tackling this serious problem.

It will be difficult to assess the impact of the CAZ while lockdown continues.  The picture will be further obscured by the closure of Cleveland Bridge for repairs over the summer, which will divert traffic through the city centre including the air quality ‘hot spots’ at Gay Street and London Street.  In the longer term, Low Traffic Neighbourhoods will displace traffic onto the network, adding to congestion and air pollution.

There are other uncertainties.  The CAZ will not apply to cars.  Older HGVs, buses and vans will still be able to come into Bath, so long as they pay.  New ‘clean’ vehicles may not turn out to be as clean as promised.

The Clean Air Plan (CAP) is designed to reduce NO₂ below the legal limit. If it fails to do that, B&NES will have to take further action until it does.  The Council may have to consider traffic reduction measures including more radical steps such as road user pricing (to which the CAZ infrastructure might be adapted).

Diesel particulates may turn out to be more harmful than currently thought, requiring further action.  Brake dust and rubber particles from tyres, which are a problem even with low or no-emission vehicles, may be the next areas of concern.  Encouragingly, the whole issue is now high on the national political agenda.

The CAP will have a limited and diminishing effect on traffic congestion.  That is a problem that remains to be tackled (and, of course, it has no effect on Carbon Dioxide, which contributes to global warming).