Air pollution and atopy

Relationships between air pollutants and atopy can be studied within 3 different settings. In vitro, exposure of pollen to air pollutants induce morphological changes and seems to facilitate extrusion on allergenic material out of the pollen grain. In animal as well as in human experiments, air pollutants, especially diesel exhaust particulates, are able to trigger an IgE-response. Epidemiological surveys also show that air pollutants trigger symptoms in patients. In contrast, whether or not air pollutants can induce de novo allergic diseases is still a matter of debate. Some surveys suggest that, in humans also, air pollutants, especially diesel-exhaust particulates, could trigger allergic sensitization and development of atopic diseases. At home, other pollutants can be involved: volatile organic compounds have pro-inflammatory properties and favour T-cell sensitization. Relationship between exposure to secondhand tobacco smoke or occupational hazards and atopic sensitization have led to discordant results.