Dictionary of Allergies .. Air Pollutant

Air Pollutant

Any substance in air that could, in high enough concentration, harm man, other animals, vegetation, or material. Pollutants may include almost any natural or artificial composition of airborne matter capable of being airborne. They may be in the form of solid particles, liquid droplets, gases, or in combination thereof. Generally, they fall into two main groups: (1) those emitted directly from identifiable sources and (2) those produced in the air by interaction between two or more primary pollutants, or by reaction with normal atmospheric constituents, with or without photoactivation. Exclusive of pollen, fog, and dust, which are of natural origin, about 100 contaminants have been identified. Air pollutants are often grouped in categories for ease in classification; some of he categories are: solids, sulfur compounds, volatile organic chemicals, particulate matter, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compound, and odors[1].The most commonly known air pollutants are SO2, NO, NO2, CO, O3, suspended dust and soot. Short-term exposure to air pollutants such as sulphur dioxide, nitrogen dioxide, and ozone results in an increase in non-allergic airways responsiveness [2].

The air pollutants may cover pollen and other allergen and damage these allergens. Dust on pollen may therefore induce both cytotoxic reactions and sensitization. In heavily polluted areas pollutants bound to pollen may modulate allergic reactions leading to a higher incidence of allergic diseases and/or alter responses in allergic individuals. Recent human and animal exposure studies, as well as laboratory-based studies, have demonstrated that diesel particles, ozone and nitrogen dioxide induce an inflammatory response that involves various inflammatory cells, mediators and adhesion molecules, which could contribute to worsening of the allergic disorders [3].This fact may explain the higher prevalence of hay fever in rural areas.

References

1. Rung-Weeke E.: Pollen allergy and atmospheric pollution: appropriate monitoring technology and clinical significance. Allergologie, Jahrgange 12, Kongressausgabe, Sept. 1989, S. 59-62.

2. Pauwels, R.: Pathogenic Mechanisms in Childhood Asthma. Triangle Suppl. 1, Vol. 26, 13-18 (1987).

3. Salvi S. Pollution and allergic airways disease. Curr Opin Allergy Clin Immunol 2001:1:35-41. Air Pollution: The presence of contaminants or pollutant substances in the air that interfere with human health or welfare, or produce other harmful environmental effects.