The problems do come in major towns and cities with heavy traffic all day - I found that my asthma was far worse working (not living) in London in the last 10 years or so (when there were far more diesel vehciles than before the Labour government encouraged people to ditch petrol cars for CO2 emissions reasons) than when I studdied at university there ten years before that, with reasonably similar levels of traffic. Particularly bad in summer. Many London areas fail miserably on the WHO/EU pollutants - I was walking along once of the worst set of roads for that - Euston Road, and believe me - its BAD.

Despite there being scientific evidence a long time ago (before the aforementioned government encouragement towards diesels) that particulates and NOx/NO2 were very harmful and that diesel vehicles were the main cause in cities (other than gas boilers, which wouldn't be an easy thing to replace), the government of the day stupidly still believed the so-called 'government/EU experts', and so did many drivers, who, despite evidence (again) warning about the pitfalls of using diesel cars for short journeys, low annual mileages (below 15 - 20k) and/or in built up areas, 'believed the hype' (not helped by the manufacturers and their [IMO] unscrupulous sales staff, who, in my view, knew all this but continued to peddle the line that they were fine and would be far better, relaible and cheaper to run than petrol-engined cars) and bought such cars in huge numbers.

Personally, I have little sympathy for drivers who bought diesel cars without doing their homework. Hopefully the new EU test (and, if it is properly representative of real world conditions/driving, ours, after Brexit) will be far more strict on the 'rule bending' (at best) the manufacturers currently use to duck under the emissions limits and we'll get data that can be actually compared to what we will really experience, and the same goes for mpg as well. People then can hopefully make a more informed choice, though with a bit of effort (and now with the help of HJ's 'Real mpg' data and from other sources) most people can already do so, with the right attitude and a bit of sense.

If there were a genuine seriousness to tackle the problem the authorities could easily take further action in London:

- congestion charge to penalise private vehicles over about 1.2 litres. A large vehicle in London is usually self indulgent and unnecessary,

- all taxis to be either hybrid or wholly electric. They rarely venture far outside Greater London so range not an issue. Charging points could be installed on taxi ranks fairly simply.

- delivery and trade vehicles to be treated largely as taxis as most are local.

- large delivery vehicles to be limited to non peak hours - say 7.00pm to 7.00am. or pay a substan

Some years ago I used to commute to paris on about a weekly basis. On a clear day when returning to Heathrow, Greater London was covered by a yellow/brown smog.

Some will object to such a draconian approach which will inevitably add to cost or reduce operational flexibility. I now live 200miles away - but Londoners have a clear choice - pay the price in either money or inconvenience to reduce pollution or accept a cra**y environment. Your choice!!