Following the UN’s report concluding carbon emissions need to be reduced massively and rapidly to prevent an average increase in global temperatures of more than 1.5C (Global warming must not exceed 1.5C, landmark UN report warns, 8 October), one quick and simple way in which the UK could make a start is by cutting the top speed vehicles can travel on motorways from 70 to 60mph. All cars operate most efficiently at a speed between 50 and 60mph. At the stroke of a pen we could ensure all vehicles on motorways are running far closer to their most efficient levels. It won’t save the world on its own, but it’s a cost-free and easy step to take that gets us moving in the right direction.

Matt Wheeler

Bushey, Hertforshire

• It is increasingly evident how difficult it will be to stop global warming; the need is pressing, obvious and requires strong leadership from governments. But, incredibly, our government is planning to build a major road (the so-called expressway) between Oxford and Cambridge. Painful as it might appear, the time has come when we have to stop building new major roads altogether, anywhere. We have to slash use of roads and fossil fuels, not encourage them.

The proposed new road would exacerbate man-made climate change, leading to increased pollution with attendant health impacts. The impacts on the environment, climate, landscape and people living in the path of the road should rule it out. Any upgraded transport links between Oxford and Cambridge must instead be via a fast, efficient, high-capacity electrified rail line.

Chris Osman

Oxford

• Your article (Air pollution and how to avoid it, G2, 8 October) omitted to mention the fact that reducing the number of journeys taken by car is an effective way of reducing exposure to toxic air. The level of toxicity inside a car is higher than that on the street. We need serious government action to deal with this public health menace but, meanwhile, you can go some way towards protecting yourself and your family, and reducing your emissions, by making the choice to drive less.

Pam Laurance

London

• My return from the newsagent’s on Tuesday morning coincided with the school run. I walked past the last 12 of a long line of cars, the owners of which had arrived early to secure a parking spot before the arrival of most pupils and parents. Of those 12 waiting vehicles, all containing young children, five had the engine running.

Bill White

Leeds

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