Free public transport could be one way to get more people to ditch the car.
The estimated economic value of minimising the damage to public health has been reduced by 80 percent.
The merchant navy – some 20,000 ships – carries the vast majority of trade goods around the world. Unfortunately, they also spew toxic pollutants that harm people and the environment.
Total emissions are coming down. But many people still live in cities with poor air quality.