Air pollution is defined as the presence in the atmosphere of pollutants that alter its composition and affect any component of the ecosystem. From an anthropocentric view air pollution it refers to contaminants that affect health or human welfare.
Depending on their origin pollutants are classified as anthropogenic, derived from human or natural activity resulting from natural processes, such as volcanic eruptions or airborne pollen. According to their physical state are gases such as sulfur oxides (SOx), nitrogen (NOx), carbon monoxide (CO), hydrocarbons and ozone (O3) or particles such as dust and aerosols.
Are considered primary when present as side were issued and when formed from the primary by a chemical reaction such as O3 and sulfuric and nitric acid. Depending on its size, the particles are deposited near or at some distance from the emission source. If you are very small they can remain suspended and be transported over long distances.
Within the suspended particles is called “breathable” to a less than or equal to 10 microns (PM10) by its ability to enter into airway diameter. The smaller particles is the greater its ability to penetrate the respiratory tree. Fine particles with aerodynamic diameter ≤ 2.5 microns easily reach the terminal bronchioles and alveoli, where they can be phagocytosed by alveolar macrophages and cross the alveolar-capillary to be transported to other organs through the bloodstream barrier.
The particles may contain organic compounds such as polycyclic aromatic hydrocarbons and / or inorganic salts such as metals. They have established “air quality standards”, which is the level of air pollutants on which the occurrence of undesirable effects are expected.
It is possible, with the help of mathematical models to calculate the extent of a toxic cloud for example from a stack of an industry. This type of study requires the participation of specialists able to determine the risk of both the probability of occurrence of the phenomenon and the severity of the disease that could be given in the recipient of this environmental toxic.