I have been reading about air pollution and I keep seeing that there are many types of pollutants in the air. I am curious which one is the most common and why it appears so frequently. Some sources talk about carbon monoxide while others focus on dust or smoke. I also read about nitrogen dioxide and ozone but I am not sure which one really dominates. It is confusing because every source mentions a different pollutant. I want to understand which pollutant most people breathe every day and what it does to health. Does it affect everyone equally or just sensitive people. If anyone has clear information about the most common air pollutant and how it impacts daily life please explain 
The most common air pollutant is particulate matter especially PM10 and PM2.5. These tiny particles come from vehicle emissions construction work and industrial activities. They float in the air and can travel long distances. People breathe them every day even if they cannot see them. It is one of the main causes of respiratory problems in urban areas.
Carbon monoxide is also very common. It is produced by burning fuels like petrol and natural gas. Cars and generators are major sources. Carbon monoxide is dangerous because it reduces the ability of blood to carry oxygen. Even short exposure at high levels can be harmful.
Nitrogen dioxide is frequently found in cities with heavy traffic. It comes from vehicles and factories. It can irritate the lungs and worsen asthma. Long term exposure may also increase the risk of heart and lung disease 