Ozone is the most injurious pollutant to plant life. Carbon monoxide Odorless and colorless gas emitted in the exhaust of motor vehicles and other kinds of engines where there is incomplete fossil fuel combustion. Cars, buses, trucks, small engines and some industrial processes. High concentrations can be found in confined spaces like parking garages, poorly ventilated tunnels or along roadsides during heavy traffic. Reduces the ability of blood to deliver oxygen to vital tissues, affecting primarily the cardiovascular and nervous systems.
Higher concentrations can cause dizziness, headaches and fatigue.
Nitrogen dioxide Light brown gas at lower concentrations becomes an important component of unpleasant-looking brown, urban haze. Result of burning fuels at electric generating plants, industrial boilers, cars and trucks . One of the major pollutants that causes smog and acid rain. Can harm humans and vegetation when concentrations are sufficiently high. In children, may cause increased respiratory illness such as chest colds and coughing with phlegm.