Spending a weekend in Europe's 10 most popular cities during summer could have the same health impact as smoking one to four cigarettes per day, according to a study.
Emissions from cars are the main source of particulate matter in the 10 cities during summer months.
Car makers consistently violate fuel efficiency laws by manufacturing vehicles that generate more pollution than the permitted levels, the study said.
"Industry claims modern diesels are clean, but checks reveal this is false, with most emitting up to 18 times the legal limit of nitrogen oxide pollution," according to the study by Transport & Environment (T&E), a European umbrella for NGO working in the field of transport and the environment, promoting sustainable transport in Europe.
"City breaks are supposed to be refreshing. But tourists are being warned that spending a long weekend in Europe's 10 most popular but polluted cities could have the same health impacts as smoking between one and four cigarettes," the study said.
London, hosting 19 million overnight international visitors per day, was ranked first, followed by Paris at 15 million.
Other cities are Istanbul, Barcelona, Amsterdam, Milan, Rome, Vienna, Prague and Dublin, the study said.
The study reveals that air quality is far worse than what the official data shows in Italy, Germany, Bulgaria and Belgium.
Meanwhile, the UK, France, Germany, Italy, Hungary and Romania face billions in fines for breaching EU air pollution standards, the study claimed.
"When air pollution is bad, we are told to avoid eating or exercising outside. But walking around cities and eating on restaurant terraces is what city breaks are all about. Right now, tourists, including kids, are more or less forced to smoke, in terms of the health impacts," said T&E air quality and diesel coordinator Jens Muller.
"City bosses need to get a grip on air pollution or risk a tourist backlash. Cars are the worst cause of air pollution in cities during the summer. Cheating carmakers should be given a deadline to truly clean up the mess they created. If they fail, polluting cars should quickly be banned from cities to protect residents," she said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.