Why is allergy increasing? environmental factors

Data from epidemiological studies have shown that allergic conditions have increased over the last 30-40 years, particularly in developed countries, d espite a decrease in the severity of grass pollen seasons. Other epidemiolo gical studies suggest an interaction between allergic diseases and traffic pollution, and laboratory findings indicate that diesel exhaust particles e nhance sensitivity to allergens. In an in vitro study, we found evidence to suggest that cigarette smoke may render the airway epithelium more suscept ible to adverse effects of allergens. Evidence from other studies indicates that O-3 and NO2, with or without SO2, can enhance the airway allergic res ponse in susceptible individuals such as those with asthma and rhinitis. St udies investigating cellular and subcellular mechanisms suggest that pollut ants are likely to influence the actions and interactions of a variety of c ells, and lead to the synthesis of proinflammatory mediators that modulate the activity and functions of inflammatory cells.