London is very literally putting a price on driving old, heavily polluting cars.

On Monday, the British capital introduced a “T-Charge,” a daily fee of £10 — or about $13 — for drivers entering the city center in cars that release extremely high emissions as part of a bid to improve the city’s air quality.

The T-Charge, short for toxicity charge, mainly applies to cars that either use diesel or fail to meet European emissions standards adopted in 2006.

The T-Charge is stacked on top of another fee for driving through Central London — the congestion charge, which costs drivers £11.50, or about $15, designed to reduce traffic in the city center while raising new money for its public transportation system.

In other words, if you’re one of roughly 34,000 motorists who doesn’t meet the new emissions standards, heading through the center of the city will cost you a whopping £21.50, or about $28. Both fees are in effect between 7 am and 6 pm, Monday through Friday.

London Mayor Sadiq Khan hailed the move as a necessary step for protecting the health of the city’s inhabitants.

“As mayor, I am determined to take urgent action to help clean up London’s lethal air. The shameful scale of the public health crisis London faces, with thousands of premature deaths caused by air pollution, must be addressed,” Khan said in a statement Monday.

The T-Charge should help control pollution. But is it enough?

Air pollution is a serious health hazard in London. A 2015 study by researchers at King’s College London found that close to 9,500 Londoners die early because of long-term exposure to air pollution in the city, much of it caused by diesel cars, trucks, and buses.

Khan told Sky News on Monday that the T-Charge would cost the city £7 million, or roughly $9.2 million, presumably because the regulation will discourage drivers from entering an area key to the city’s economy and hamper productivity. But he said the cost was a “price worth paying.”

The new T-Charge is actually a stepping stone to a more stringent standard. It will be replaced by an “Ultra Low Emission Zone” in 2019, which will bring the pollution fee up to £12.50, currently about $16.50, in addition to the congestion charge. Khan is also angling to expand the area in London covered by the pollution fee by 2021.

There are concerns that the fee functions as a tax on lower-income drivers who can’t afford to purchase a new vehicle that meets emissions standards — yet also can’t afford to avoid driving into the city center for work.

Some environmental advocates believe financial carrots are as important as sticks for incentivizing a real pivot toward cleaner cars. "We urgently need a program of meaningful financial assistance to help drivers of the dirtiest vehicles switch to something cleaner, and bold policies to cut traffic overall," Friends of the Earth campaigner Jenny Bates told Sky News.

Some environmental activist groups think Khan’s measure doesn’t go far enough to control pollution. Simon Birkett, the director of Clean Air London, said in a statement that the T-Charge is an “important step” but that the city “must “take bigger, stronger and smarter steps.” He says the low emissions zone should be expanded more quickly than the city expects to, and calls for an outright ban on diesel vehicles.

Khan doesn’t appear to be moving toward any ban yet — but he’s certainly causing drivers to rethink how they want to move around the city.