As new figures suggest a decline in diesel car purchases, Global Action Plan's Senior Partner, Chris Large, shares his thoughts on what this could mean for air pollution, and for the future of diesel.

May 2017 could go down in history as the month that diesel cars turned a corner signed "Dead End". Figures just released by the SMMT show that new diesel car registrations in May 2017 were down by a whopping 20% on last year. That is 20,000 fewer diesel cars going on to the roads than in May 2016. Car registrations on the whole are down by 8.5%, but with diesel down by 20%, that takes the share of the market for diesel down from 50% to 43.7%. I find this cause to celebrate for two reasons.

Firstly, every car, and especially every diesel, that isn't driving around reduces the amount of air pollution caused in our cities, which we know has the equivalent health impact of 40,000 premature deaths each year in the UK. Secondly, it shows the power of people's choices to bring about a huge shift in the environmental damage we cause.

I find this second point fascinating. While establishing National Clean Air Day, I've often been asked (and occasionally challenged) about whether people can do anything serious to combat air pollution or whether it needs to be left to the government. My typical response is that whilst government policy has encouraged diesel for many years through favourable fuel taxes, it is not the government that is buying or leasing new cars. That's us. Or more specifically, that's members of the public, and fleet managers in companies and the public sector. The government can nudge behaviour with taxes that make certain options more or less expensive, but ultimately the choice is still ours. If you abhor the idea of a nanny state manipulating your every move, it’s a little weak to then say “I must buy diesel because the state has made it a bit cheaper than petrol”. If people decide to, they can prioritise clean air at their next upgrade. And now it seems many people are making that choice.

As well as the 20,000 fewer diesels on the road, the London Taxi Company is ditching diesel (they will only sell electric black cabs from 2018 onwards). Diesel buses in Leeds, Nottingham and London are reducing innumber (to name just a few cities). Two-thirds of all miles driven in an Uber are in alternative fuel vehicles, and last weekend I saw two friend's jockeying for position with their electric cars to get an overnight charge outside the house in Epping.

If this is the end of the road for diesel, we can stop debating if people are powerless and praise those with the principles and passion to ditch the diesel. Whether they make that choice as an individual, a parent or a fleet manager, I applaud them.