Yes, I think vehicles are a big reason for air pollution, especially in cities. Cars, buses, and trucks all release a lot of exhaust fumes, and when there are traffic jams, the air gets even worse. Most vehicles still use petrol or diesel, which are not clean fuels. Also, with more delivery services and ride-sharing, there are even more cars on the road now, making the problem bigger.

No, I don't think vehicles are the only cause. Factories and power plants also release a lot of pollution into the air, especially when they burn coal for electricity. In some places, construction sites and even farming, like burning crop waste, can make the air dirty too. So, there are many sources, not just vehicles.

I think it depends on where you are. In big cities, cars and buses are probably the main reason for air pollution because there are so many of them. But in the countryside or in industrial areas, factories or farms might be the bigger problem. Also, in some countries, there are strict rules for vehicles, so factories might cause more pollution instead.