Your emissions zone article (Coming soon: the £24 charge for driving into central London, 5 January) correctly states that most pre-2006 cars will fall foul of Transport for London’s post-2021 ultra-low emission zone (ULEZ) standard rules for driving within London’s north and south circular roads without charge. These new rules are grossly crude and inept if the aim is to reduce air pollution. Age of vehicle on its own is a very poor indicator of the pollution caused by a car.

Much more important is the mileage. We have a pre-2006 car, but travel fewer than 750 miles a year: we only use the car about once every three weeks for journeys especially requiring a car. Therefore TfL should use car mileage (easily obtained from MOT records) instead of age. A more valid decision model would also use the residence postcode of the vehicle to estimate difficulty of using public transport: we are lucky to live near an excellent transport hub, so it is easy for us to use the underground and buses as much as we do.

David Lawrence

London

• It’s heartwarming to see the Conservatives in the Greater London Authority standing up for the poorest in society: they will be hardest hit by the new ultra-low emissions charges, as GLA Tory leader Gareth Bacon told the Guardian. Except that the poorest are most likely to live in the worst-polluted areas, but least likely to own a car. The most recent stats available are that 46% of London households do not own a car.

For the lowest income decile, only 19% of households had a car, against 80-83% of the three top income deciles. Coincidentally, London’s highest average incomes are in the area covered by the central London ULEZ area. Seems like there should be more effective ways to help London’s poorest.

Judith Hanna

London

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