Inside Science reports on the congestion charge in Stockholm (Link to actual paper). Stockholm always has been a city with relatively clean air and PM10 and NOx levels well below limits. The introduction of a congestion charge in 2007 reduced air pollution in Stockholm by approximately 10 percent. Yet, after several years, Asthma in children 0-5 years old is reduced of 45 percent.
“It appears that what they’ve found is these cumulative effects of pollution,” he said.
The article also reminds city policy makers that a congestion charge can only work if a viable public transport infrastructure is already in place.