Air pollution is caused mainly by the burning of fossil fuel, which include coal and oil. When coal is burned it releases a large number of airborne pollutants and toxins in the environment. It includes sulfur dioxide, nitrogen oxides, mercury and lead, and various other metals.
Carbon dioxide is considered as a good indicator of how much fossil fuel is burnt and how much of pollutant is released into the atmosphere.
Los capilares rodean a las células y a los tejidos del cuerpo para aportar y absorber oxígeno, nutrientes y otras sustancias. Los capilares también conectan las ramas de las arterias y las ramas de las venas.
