Air

Humans first experienced their first harmful air is when they built fired in poor ventilated caves. After that time, we have been polluting air more and more. The main air pollutants found in urban areas are carbon monoxides, nitrogen oxides and hydrocarbons. I was surprised when i read this article. It says EPA has found that air in some office buildings are 100times polluted than air outside. Poor ventilation is the main cause of these indoor air pollutions.