| How Exposure to Environmental Tobacco Smoke, Outdoor Air Pollutants, and Increased Pollen Burdens Influences the Incidence of Asthma M. Ian Gilmour,1 Maritta S. Jaakkola,2 Stephanie J. London,3 Andre E. Nel,4 and Christine A. Rogers5 1U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA; 2Institute of Occupational and Environmental Medicine, University of Birmingham, Birmingham, United Kingdom; 3National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA; 4Department of Medicine, University of California Los Angeles, Los Angeles, California, USA; 5Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA 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. Key words: air pollution, asthma, cigarette smoke, climate change, diesel exhaust, environment, inflammation, mechanisms, ozone, particulate matter, pollen. Environ Health Perspect 114:627-633 (2006) . doi:10.1289/ehp.8380 available via http://dx.doi.org/ [Online 26 January 2006]
This article is part of the mini-monograph "Environmental Influences on the Induction and Incidence of Asthma." Address correspondence to M.I. Gilmour, U.S. EPA, Research Triangle Park, NC 27711 USA. Telephone: (919) 541-0015. Fax: (919) 541-4284. E-mail: gilmour.ian@epa.gov All authors contributed equally to the development of this review article. We are grateful to S.H. Gavett for careful review of the manuscript. This paper has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. EPA, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the agency, nor does the mention of trade names or commercial products constitute endorsement or recommendation for use. The authors declare they have no competing financial interests. Received 3 June 2005 ; accepted 26 January 2006.
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