Example :  When Paris centre went car-free in 2015, levels of nitrogen dioxide fell to 40% in parts of the city, and sound levels dropped by half in the city centre.

Explain : The government has set aside a day for car-free, so residents conceive its importance.
Example: Over the years, more and more countries celebrate
car-free days.
Body 2 : While there are a huge range of ways to protect air environment 

Explain : factory discharge is the Principal reason cause the air quality deterioration . Total global CO2 emissions in 2021 amount to 36.4 billion tons and show no signs of stopping. It is a warning bell for countries that do not take the rigors of factory waste reduction laws seriously. From that fact, the punishment policies for indiscriminate waste factory should be increased ( governments = states )
Main idea 2 : 

-       Reducing traffic congestion in big city 

 Example : economic growth is directly proportional to the better of living standard. Every family will have at least one car in the near future. But in the ……….. days, cars will be replaced by walking and cycling, so that traffic congestion will be reduced.

-       Less greenhouse gas

Example : more cars means more carbon dioxide, this will lead to increase the harmfulness from one of the biggest problems that human have to deal with, which is global warming. This also plays a very crucial role to raise people’s awarness when they can inhale the fresh air in these days to stop using car.

Body 2.  Another solution

-       Still using car, but electricity consumption one

Example : Tesla, a car company which is found by Elon Musk, they have invented one of the most successful electric car for the last decades. Vinfast, a car company from Vietnam has to stop manufacturing gas consumption car to deal with a large numbers of orders with their latest model.