People urged to be wary of 'smog' in Leicester
People with asthma, or conditions affected by poor air quality, have been warned by Leicester City Council to be aware of high pollution levels.
A "smog alert" remains in place nationally over the Easter weekend.
High pollution levels are being blamed on the warm, still conditions brought on by a high pressure system.
Adrian Russell, the city council's director of environmental services, said the problem was likely to be worse outside urban areas.
He said: "One of the particular problems that's given rise to this smog warning is the fact that the sunshine is acting on traffic pollutants, which causes a particular problem with ozone as a pollutant.
"And funnily enough that ozone is more likely to be a problem in rural areas than city areas."