Authorities in Paris have decided to take a rare step of making public transportation free for three days to reduce smog caused by unusually warm weather.

The French capital region and at least 30 other departments have been on "maximum pollution alert" for several days now, according to BBC.com.

The air quality in the capital has been one of the worst on record, according to French environmental agencies.

Cold nights followed by warm days and a lack of wind have been contributed to the worsening conditions, according to BBC.com.

Commuters in Paris, and neighboring locations, will not have to pay for public transport between Friday and Sunday.

 Bike services are also free, along with one-hour sessions for electric car shares, according to the Associated Press.

Levels of smog recorded in Paris this week is similar to those of Beijing in China, which is one of the most polluted cities in the world.

The smog has also been affecting Belgium, where official have tried reducing the maximum speed limit on main roads to help reduce it, according to BBC.com. The southern Wallonia region said it has decided to make trains, underground trains, and buses free until the emergency is over as well.

"I am asking all residents in Paris and neighboring areas to favor the use of public transport," said Jean-Paul Huchon, the head of the capital's transport authority, according to BBC.com.

Children, people with asthma or heart problems, and elderly people, have been advised to stay inside to avoid potential breathing issues.

Other French cities like Reims, Caen, and Rouen, have announced they will also make public transportation free over the weekend as well, according to BBC.com.

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