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INTRODUCTION

Work-related asthma (WRA) is an important topic in public health and preventive medicine. It is associated with a high population burden, affecting millions in the United States (U.S.) alone. It is also preventable through primary and secondary public health interventions. This chapter will provide a brief introduction to WRA, including pathophysiology, epidemiology, diagnosis, and prevention in individuals and populations.

Overview of Asthma

Asthma is a chronic relapsing, usually inflammatory disorder characterized by hyperreactive airways (increased responsiveness of the tracheobronchial tree to various stimuli) and episodic, reversible airways obstruction.1,2 Recurring symptoms include wheeze, shortness of breath, chest tightness, and cough. Asthma is very common in the U.S. Based on estimates in 2017, 19 million adults currently had asthma for a prevalence of 7.7%, and lifetime prevalence was 13.4%.3

Work-Related Asthma

WRA includes both occupational asthma (OA) that is caused by exposures at work, and work-exacerbated asthma (WEA) in which pre-existing or concurrent asthma is worsened by exposures or conditions at work (Fig. 76-1).4–7 OA is new-onset asthma or the recurrence of asthma that had been in remission (i.e., asymptomatic and not requiring asthma medications) attributable to either a sensitizer or an irritant in the work environment.7,8

FIGURE 76-1

Relationship of work-related asthma, occupational asthma, and work-exacerbated asthma. See text for full description.

Sensitizer-induced OA cases are typically categorized based on whether the causative agents are high-molecular weight (HMW) (i.e., > 10,000 Daltons) agents such as proteins, or low-molecular weight (LMW) (i.e., < 10,000 Daltons) agents such as reactive chemicals. Examples of common HMW agents include allergens from laboratory animals, insects, flour, enzymes, and natural rubber latex (NRL). Examples of common LMW agents include diisocyanates, colophony fluxes, solders, plicatic acid found in western red cedar wood dust, acrylates, and glutaraldehyde.9 One of the more comprehensive and up-to-date online lists of OA agents is available from the Quebec provincial government.10 A summary of this list of agents is shown in Table 76-1.

TABLE 76-1OCCUPATIONAL ASTHMA AGENTS COMPILED BY QUEBEC PROVINCIAL GOVERNMENT IN CANADA10

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