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Environmental Triggers of Asthma
Overview of Asthma

Course: WB 1102
CE Original Date: October 17, 2007
CE Renewal Date: October 17, 2010
CE Expiration Date: October 16, 2012
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Learning Objectives

Upon completion of this section, you will be able to

  • define asthma, and
  • identify environmental factors that trigger asthma.

Purpose of This Case Study

This Case Study in Environmental Medicine focuses specifically on the environmental factors that contribute to asthma expression and severity. The goal is to identify those factors, with the hope of moderating or eliminating exposures or reducing their effect.

This case study is not a comprehensive review of asthma, nor a complete review of asthma management. Asthma assessment, monitoring, pharmacotherapy, and patient education have been covered at length in many excellent texts and articles (Williams et al. 2003).

Definition of Asthma

The National Heart, Lung, and Blood Institute defines asthma as “…a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role, in particular, mast cells, eosinophils, T lymphocytes, airway macrophages, neutrophils, and epithelial cells. In susceptible individuals, this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning. These episodes are usually associated with widespread but variable airflow obstruction that is often reversible either spontaneously or with treatment. The inflammation also causes an associated increase in the existing bronchial hyper responsiveness to a variety of stimuli” (NHLBI 2003).

Incidence and Prevalence

Allergic diseases such as asthma, rhinitis, and eczema are increasing in prevalence. They affect up to 15% of populations in Westernized countries (Robinson et al. 2004). The increasing incidence and prevalence of asthma in many parts of the world continues to make it a global health concern (NHLBI 2004). Asthma is one of a few diseases in the United States that are increasing in incidence among children and adults. This is despite scientific advances in improving treatment outcomes and understanding the pathogenesis (IOM 2000).

The last several decades have seen a significant rise in the rate of pediatric asthma. From 1980 to 1996, asthma prevalence among children increased by an average of 4.3% per year. As of 2002, 9 million U.S. children under 18 years of age (12%) had at some time in their lives been diagnosed with asthma. Of those, 4.2 million had experienced an asthma attack within the previous year (Dey et al. 2004).

Factors That Contribute to Asthma

Environmental factors that contribute to asthma symptoms and severity include

  • viral infections (Gern 2004; Martinez 2003; Lemanske 2003),
  • allergens, such as dust mites, cockroaches, animal dander, and molds (Murray et al. 2001; Togias 2003; Jaakkola et al. 2005),
  • irritants, such as environmental tobacco smoke (ETS), and exposures to certain chemical fumes, gases, or vapors (Tager et al. 1993; Weitzman et al. 1990; Martinez et al. 1992; Malo et al. 2006), and
  • miscellaneous causes such as exercise, food allergies, gastroesophageal reflux, aspirin or other nonsteroidal anti-inflammatory drug (NSAID) sensitivity, sulfite sensitivity, and others (Weinberger 2003; NHLBI 1997, 2003).

This Case Study focuses on preventable environmental asthma triggers and measures that may decrease their effects on patients.

Key Points

  • Asthma is a chronic inflammatory disease.
  • It is increasing in prevalence.
  • It is triggered by many various environmental factors.

Progress Check

1. Which of the following is not a symptom of asthma

A. Wheezing.
B. Seizures.
C. Shortness of breath.
D. Cough.


To review relevant content, see Definition of Asthma in this section.

2. Common environmental triggers of asthma include

A. Allergens.
B. Irritant chemicals
C. Viral infections
D. All of the above.


To review relevant content, see Factors Which Contribute to Asthma in this section.

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