Over 5,000 police officers headed out onto Polish roads on Tuesday hunting for vehicles which cause excessive pollution.
Police were checking the roadworthiness of cars as well as emission levels.
The police campaign, called operation “Smog,” is the third of its kind in Poland this year.
Scientists estimate that between 60 and 80 percent of air pollution in big Polish cities comes from road transport, public broadcaster Polish Radio’s IAR news agency reported last month.
Owners of vehicles in poor condition or which have failed to pass annual roadworthiness checks are liable to a fine of up to PLN 500 (EUR 116, USD 132).
Polish police have said they checked more than a quarter of a million vehicles for emissions last year, taking some of them off the roads.
According to a report by the World Health Organisation (WHO), out of the 50 European cities most affected by smog, 33 are in Poland. The WHO estimates that around 50,000 Poles die every year due to illness caused by air pollution.