It has a strong smell at high levels. Nitrogen dioxide mostly comes from power plants and cars. Nitrogen dioxide can also react in the atmosphere to form ozone, acid rain, and particles. High levels of nitrogen dioxide exposure can give people coughs and can make them feel short of breath. People who are exposed to nitrogen dioxide for a long time have a higher chance of getting respiratory infections.
Acid rain can hurt plants and animals, and can make lakes dangerous to swim in or fish in.
Solid or liquid matter that is suspended in the air. To remain in the air, particles are usually less than 0.1 mm wide, and can be as small as 0.00005 mm. Coarse particles are bigger than 0.002 mm, and are formed from sources like road dust, sea spray, and construction. Fine particles are smaller than 0.002 mm, and are formed when fuel is burned in automobiles and power plants. Particulate matter that is small enough can enter the lungs and cause health problems.