Since signing the Paris Agreement in 2016, the country has been committed to cleaning its air. President Moon Jae In’s administration vowed to shut down old coal plants (while also opening up new ones) and to cut domestic emissions by 30 percent by 2022. On the local level, Seoul has been nudging its residents to take the more environmentally friendly route by building bike paths, pedestrian-only zones, and, most notably, a five-mile High Line-styled park. It also replaced diesel buses with natural gas vehicles and provided emission-reducing devices to car owners.

As part of an emergency plan announced last year by Seoul Mayor Park Won Soon, the city will make public transit free during rush hours on days when the air quality index reaches above 50 and is expected to stay there for at least a day. Free rides will be provided on the second day as well. To pay for the measure, Park set aside 24.9 billion won (about $23 million) in December, declaring the worsening air a disaster in order to tap into the city’s disaster-management fund. “The value of human beings is far greater than that of money,” he said last year.

Making transit free (or at least cheaper) is not an uncommon strategy to combat air pollution: Paris began offering free transit in response to smog in 2014, Milan slashed fares on its worst days, and Madrid has put out a proposal to do much the same. As a megacity with one of the most highly praised transit systems, Seoul seemed a good candidate to make the strategy work.

Yet as the air continues to worsen, critics argue that money could be, and should have been, better spent. The daily paper Chosun Ibo reports that the city swallows roughly 5 billion won (about $4.7 million) in lost fares each day the measure is in effect. That means more than half the funds have already been used up in the span of just one week—and with unremarkable results. Road traffic fell only 1.8 percent on Monday (a little over 2,000 vehicles). Meanwhile subway ridership increased by 23,000 people and bus ridership by 3,500. On Wednesday and Thursday, traffic volumes decreased by only 1.7 and 2.4 percent, respectively.

What’s more, Park’s political opponents have criticized his move as illegal, arguing that micro-dust was never written into the city’s disaster and safety management legislation, and that Park is using the measure to win votes for a regional election in June. Legality and political controversy aside, even environmentalists have voiced concerns over the temporary and, more importantly, voluntary nature of the whole plan. With the exception of closing parking lots and implementing alternate-day driving systems for public employees, the city stopped short of issuing any mandates for the average driver.

“In the long term, this is going to need to be mandatory rather than voluntary, and instituted on a daily basis rather than as an emergency measure,” Lee Se Geol, secretary-general for the Seoul chapter of the Korean Federation for Environmental Movement, told South Korea’s daily newspaper The Hankyoreh in 2017.