Respirator Physiological Effects under Simulated Work Conditions

Abstract

This study compared the physiological impacts of two respirator types in simulated work conditions. Fifty-six subjects included normal volunteers and persons with mild respiratory impairments (chronic rhinitis, mild COPD, and mild asthma). Respiratory parameters and electrocardiogram were measured using respiratory inductive plethysmography while performing eight work tasks involving low to moderate exertion using two respirators: (1) a dual cartridge half face mask (HFM) respirator, and (2) the N95. Mixed model regression analyses evaluating the effect of task and respirator type showed that task affected tidal volume, minute ventilation, breathing frequency and heart rate; all were greater in heavier tasks. Although respirator type did not affect respiratory volume parameters and flow rates, the HFM led to increase in the inspiratory time, reduction of the expiratory time, and increase in the duty cycle in comparison with the N95. The magnitude of differences was relatively small. The results suggest that most individuals, including persons with mild respiratory impairments, will physiologically tolerate either type of respirator at low to moderate exertion tasks. However, because effective protection depends on proper use, differences in subjective effect may have greater impact than physiological differences. Using respirators may be feasible on a widespread basis if necessary for maintaining essential services in the face of widespread concern about an infectious or terrorist threat.

Subjective Response to Respirator Type: Effect of Disease Status and Gender

“…Tasks used for the work simulation included both sedentary and more active tasks; the tasks are summarized in Table 1 and described elsewhere, 9,10 including an article in this issue. 14 The tasks were as follows: i) Sedentary: familiarize subject with rating procedures (lern); sort bolts into bins (bolt); simulate driving (driv); produce towers with plastic blocks after prescribed instructions (lego).…”

“…6 -8 and other factors may be more important. This study is part of a project to characterize the overall response to respirator use; other aspects include physiologic responses, 9 productivity effect, mask dislodgement, and anxiety. The development and characterization of the subjective response scales were described in an earlier study.…”

Respirator Impact on Work Task Performance

“…Selection and exclusion criteria have been described elsewhere. 2,18 The research protocol was approved by the institutional review boards of the University of California, Los Angeles (UCLA) and of the Greater Los Angeles Veterans Administration Medical Center. Subjects were recruited from clinics associated with the Greater Los Angeles Veterans Administration Medical Center and the UCLA as well as by newspaper and other advertisements.…”

“…The methods and hardware/software are described in detail elsewhere. 2 volume method was used for calibration. The subjects also completed a series of subjective ratings concerning comfort, facial conditions, concentration, and other variables.…”

“…Frequently, however, they serve an additional purpose-allowing continuation of productive activities that would otherwise be precluded. While there has been extensive investigation of the degree of protection afforded by respirators, their physiologic consequences, [1][2][3][4][5][6] and exercise limitation, 7-13 the actual impact upon work productivity has not been carefully evaluated. 14,15 Impact on accomplishing activities may be relevant in nonoccupational 16,17 as well as workplace settings, particularly if use will be prolonged.…”