How Exposure to Environmental Tobacco Smoke, Outdoor Air Pollutants, and Increased Pollen Burdens Influences the Incidence of Asthma

Abstract

Asthma is a multifactorial airway disease that arises from a relatively common genetic background interphased with exposures to allergens and airborne irritants. The rapid rise in asthma over the past three decades in Western societies has been attributed to numerous diverse factors, including increased awareness of the disease, altered lifestyle and activity patterns, and ill-defined changes in environmental exposures. It is well accepted that persons with asthma are more sensitive than persons without asthma to air pollutants such as cigarette smoke, traffic emissions, and photochemical smog components. It has also been demonstrated that exposure to a mix of allergens and irritants can at times promote the development phase (induction) of the disease. Experimental evidence suggests that complex organic molecules from diesel exhaust may act as allergic adjuvants through the production of oxidative stress in airway cells. It also seems that climate change is increasing the abundance of aeroallergens such as pollen, which may result in greater incidence or severity of allergic diseases. In this review we illustrate how environmental tobacco smoke, outdoor air pollution, and climate change may act as environmental risk factors for the development of asthma and provide mechanistic explanations for how some of these effects can occur.

Indoor airborne fungi and wheeze in the first year of life among a cohort of infants at risk for asthma

“…Evidence suggests that the development of asthma occurs primarily during early childhood and involves both genetic and environmental factors including biologics (e.g., allergens, viruses, bacterial products). The timing and ''dose'' of the environmental exposures and the interaction with genes and other susceptibility factors (e.g., breast-feeding, lifestyle) during specific developmental periods appear critical to the induction of asthma (Martinez, 2003;Yeatts et al, 2006;Gilmour et al, 2006;Zeldin et al, 2006;Selgrade et al, 2006). It is likely that fungal allergens eliciting immunological and airway changes during this critical developmental period are dependent in part, on the geographic area and climate (Martinez, 2002), perhaps accounting for the variety of fungal taxa-respiratory symptom associations which have been observed.…”

Repeated hospital encounters for asthma in children and exposure to traffic-related air pollution near the home

“…When antioxidant responses are then overwhelmed, airway inflammation may follow, leading to increasing asthma symptoms in susceptible children. 19,33 Potentially Susceptible Subgroups There was no significant difference in association by sex or age group, and widened confidence intervals in stratified results suggest that subsample sizes may have limited the ability to compare these groups. Nevertheless, the largest associations were for infants, followed by children aged 6 to 18 years, in whom the diagnosis of asthma is clearest.…”

Sensitization to profilin in the Central region of Portugal

“…The high allergen exposure namely to pollens, is one of the pointed factors that has been linked with the increase in prevalence of allergic diseases such as asthma, and rhinoconjunctivitis (Jarvis and Burney, 1998;Taylor et al, 2007;Gilmour et al, 2006). Climate changes result in an increase of the allergen burden, a fact that combined with pollutant exposures, can act synergistically to enhance the allergic response, and increase respiratory symptoms (Gilmour et al, 2006;D'Amato et al, 2007a,b;Beggs, 2004).…”

“…Climate changes result in an increase of the allergen burden, a fact that combined with pollutant exposures, can act synergistically to enhance the allergic response, and increase respiratory symptoms (Gilmour et al, 2006;D'Amato et al, 2007a,b;Beggs, 2004). The patterns of sensitization to pollens depend on exposure and differ according to region, since the climate, geography, and vegetation diverge (D'Amato et al, 2007a,b).…”