Britain has the worst road pollution in Europe, says a new report.
It found hundreds of local authorities are breaking European Union limits on fumes which can harm your health and cause conditions like asthma.
The fumes on certain stretches of roads break safety levels in 95% of cities and areas in the UK.
The study warns that Britain will break EU air pollution laws and could be forced to pay big fines unless it takes action to cut traffic pollution.
One of the reasons Britain is doing badly in the table is because there are lots of people living in a small area compared to many other European countries.
Some experts reckon that introducing more electric cars or charging people to use roads could help.
The report also says the UK will miss its EU targets to reduce the amount of nitrogen dioxide produced to safe levels by 2010.