More than 50 per cent of air pollution is caused by ____________

Explanation

**Step-by-Step Solution:**

1. **Understanding Air Pollution**: Air pollution refers to the presence of harmful substances in the atmosphere, which can negatively affect human health and the environment.

2. **Identifying Major Sources**: Among the various sources of air pollution, vehicles and transportation play a significant role. They contribute to more than 50% of the total air pollution.

3. **Types of Pollutants from Vehicles**: Vehicles emit various harmful gases, including carbon dioxide (CO2) and carbon monoxide (CO), which are major contributors to air pollution.

...