Multiple smokestacks releasing pollutants into the air in the form of white smoke, burning natural gas, and black smoke.

Credit: UCAR

Factories like this oil refinery are a major source of air pollutants, including toxic metals, particulates, and many types of gases (nitrogen oxides, sulfur oxides, methane, carbon monoxide, benzenes, and others). Many of these gases contribute to the formation of ozone pollution and are causing the climate to warm due to the greenhouse effect.