Air Pollution and Asthma

Abstract

Asthma is a chronic inflammatory airway disease most commonly associated with an eosinophilic (TH2-type) inflammation. Airway pathophysiology of asthma is characterized by intermittent airway bronchoconstriction and mucus hypersecretion with decreased airflow, cough, wheeze and breathlessness. These events are linked to airway hyperresponsiveness, in which airway response to environmental stressors is increased. Environmental exposures are an important factor in asthma genesis. Allergic processes play a defining role in atopic asthma, with allergen exposures linked to disease development. Occupational exposures and chronic exposure to ambient air pollutants and tobacco smoke have been linked to asthma. A common cause of asthma exacerbation is acute exposure to environmental pollutants, including ozone, particulate matter, wood smoke, tobacco smoke, and bioaerosols. Pollutant exposure also increased responsiveness to viral infection inhaled allergen. Features that characterize most air pollutants that play a role in asthma are the ability to induce an innate immune response and association with increased oxidative stress. Biological factors and interventions that modulate innate immunity and oxidative stress impact environmental asthma as well. This chapter will outline the effects of a number of pollutants in asthmatics, as well as potential interventions to mitigate the impact of pollutants on asthmatics.