Air pollution chemicals linked to asthma

Chemicals created by the incomplete combustion of coal, oil, gas and other substances are linked to an increase in asthma in children, U.S. researchers say. Dr. Kari Nadeau studied the effects of polycyclic aromatic hydrocarbons on a sample of children and found that increased exposure to these chemicals in air pollution were associated with certain immune system effects and asthma diagnosis. "We already know that immunoglobulin E plays a role in asthma development and increased immunoglobulin E levels result when asthmatics are exposed to triggers like pollutants," Nadeau, the senior study author, said in a statement. "There is also growing evidence that regulatory T cells, which are a specific kind of cell that modulates the immune system, play an important role in inhibiting allergic sensitization and immunoglobulin E production after exposure to an allergen. Regulatory T cell numbers are reduced in patients with asthma." A total of 332 children between the ages of 10-18 were given questionnaires and a lung function test. The study found the higher levels of polycyclic aromatic hydrocarbons exposure were linked to increased total immunoglobulin E levels. Significantly weakened regulatory T cell function was also observed in those children who had been exposed to higher amounts of polycyclic aromatic hydrocarbons, the study said. The study was presented at the annual meeting of the American Academy of Allergy, Asthma & Immunology in San Antonio.