London Mayor Sadiq Khan urged Prime Minister Theresa May to back the expansion of Gatwick Airport to show the world that the U.K. capital is “open for business” after Britain voted to leave the European Union.

Expanding London’s second-busiest airport would provide the extra aviation capacity the capital needs, without the environmental cost of building an extra runway at the biggest hub, Heathrow, Khan wrote in a letter to May, according to an e-mailed statement on Wednesday from his office. He said making a quick decision should be a top priority for May’s administration.

“London’s economy needs additional aviation capacity in order to stay competitive with other major global cities and an early decision from you would show to the world that we are open for business,” Khan wrote. “A second runway at Gatwick will bring substantial economic benefits to London and the U.K. in terms of jobs, growth and investment.”

May has faced accusations she’s deterring investment in the U.K. after she stalled an 18 billion-pound ($24 billion) deal for Electricite de France SA to build a new nuclear plant, with China taking a minority stake. The deal had been in the works for years, and the delay stoked concern she’ll put off other overseas investors at a time when Britain needs to expand commercial ties beyond the 27 other EU members.

Successive Delays

A government-appointed commission led by Howard Davies concluded last year that adding a runway at Heathrow, west of London, offered the best solution to the looming capacity crisis, rather than a rival plan for Gatwick, to the south. Even so, concerns about air pollution at Heathrow, the London mayoral election in May and the referendum on EU membership in June led to successive delays by May’s predecessor, David Cameron, with the decision being pushed back to October at the earliest.

The government separately gave the go-ahead in July for a 344 million-pound ($450 million) extension plan for London’s City Airport after Khan withdrew an objection made under the previous mayor, Boris Johnson, blocking the purchase of land needed for new taxi-ways. That’s a fraction, though, of the 18.6 billion pounds it would cost to built a third runway at Heathrow.

Poor air quality is a possible stumbling block to Heathrow expansion because monitoring sites close to the hub have exceeded EU limits on nitrogen dioxide in recent years. The pollutant has been blamed for thousands of deaths in London. Gatwick, situated in a much less densely populated area, doesn’t face the same constraints as Heathrow, under whose flight path May’s Maidenhead electoral district is situated.

©2016 Bloomberg L.P.

This article was written by Alex Morales and Thomas Penny from Bloomberg and was legally licensed through the NewsCred publisher network.

Photo Credit: An aircraft comes in to land at Heathrow. The airport is one of the shortlisted locations for a new runway. Toby Melville / Reuters