Physiological and subjective responses to working in disposable protective coveralls and respirators commonly used by the asbestos abatement industry

Our plain-English summary of Physiological and subjective responses to working in disposable protective coveralls and respirators commonly used by the asbestos abatement industry, by M.K. White, T.K. Hodous, J.B. Hudnall (American Industrial Hygiene Association Journal, 1989).

The study

• Authors: M.K. White, T.K. Hodous, J.B. Hudnall
• Journal: American Industrial Hygiene Association Journal
• Published: 1989;50(6):313-9
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004474).

Abstract

The physiological and subjective effects of working with different respirators while wearing lightweight disposable (Tyvek 1412 polyolefin) coveralls commonly used by the asbestos abatement industry were studied. Nine healthy men (mean age = 27.3 yr, weight = 76.9 kg) each performed a series of four exercise tests with four different respirator ensembles in counterbalanced order. Treadmill work was performed at a set walking speed of 4 kph (2.5 mph), 0 percent elevation (220 kcal/hr), a controlled environmental temperature of 33.9 degrees C, and 50% relative humidity. Each test continued up to 120 min, with repeated work/rest intervals of 26 min of work and 4 min of rest. Tyvek disposable coveralls and hoods were worn with each of these four different respirator ensembles: (1) control--a lightweight, low resistance mask; (2) HEPA--an air purifying, full facepiece respirator with dual high efficiency filters; (3) SAR--a supplied-air, pressure-demand respirator with escape filter; (4) SCBA--an open circuit, pressure-demand, self-contained breathing apparatus. Physiological measurements obtained every minute during each test included heart rate and skin and rectal temperatures. Subjective evaluations of clothing, respirator, and facepiece comfort, ease of breathing, temperature and perspiration in the mask and clothing, and respirator load also were measured at the end of the test. Data were analyzed using an analysis of variance. Results indicated that heart rate at the end of the test differed by less than 8 BPM between the control condition and the SCBA (heaviest) condition.(ABSTRACT TRUNCATED AT 250 WORDS)

In plain English

This was a laboratory experiment testing protective gear used in asbestos abatement. It did not study asbestos exposure or disease. Nine healthy male volunteers, aged 22 to 34 and experienced firefighters or emergency service workers, each did four treadmill sessions of up to 120 minutes at a slow walk, in a room held at 33.9°C and 50% relative humidity. In each session they wore disposable Tyvek coveralls and a hood with one of four breathing set-ups: a lightweight control mask not designed for protection, a full-facepiece respirator with HEPA filters, a supplied-air respirator, or a self-contained breathing apparatus (SCBA). Average end-of-test heart rates were 153.2 beats per minute with the control mask and 160.9 with the SCBA, a difference that was not statistically significant. Skin temperature, rectal temperature, sweat loss and time tolerated also did not differ significantly between set-ups. Of the subjective ratings, only perceived respirator load differed significantly; it was rated higher for the SCBA. The authors concluded that in some low-workload abatement settings, heavier, more protective respirators may add only minimal stress. They noted that the subjects were young and healthy and that the work was light.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory exercise experiment (crossover): each subject tested all four respirator ensembles in counterbalanced order; analyzed as a randomized complete block design with analysis of variance
• Who was studied: Nine healthy male volunteers, current nonsmokers aged 22 to 34 years (mean 27.3), who were experienced local firefighters or emergency service personnel with prior respirator and protective clothing experience
• Exposure: No asbestos exposure. Subjects wore Tyvek 1412 disposable coveralls and hood with four respirator ensembles: a control low-resistance mask, a HEPA full-facepiece air-purifying respirator, a supplied-air pressure-demand respirator (SAR) and an open-circuit pressure-demand SCBA. Total ensemble weights were 3.2, 4.0, 4.8 and 13.1 kg respectively. They walked on a treadmill at 4 kph, 0% grade (about 220 kcal/hr) at 33.9°C and 50% relative humidity, for up to 120 min in cycles of 26 min work and 4 min rest.
• Main results:
  • Mean tolerance times were 117.9, 114.1, 116.4 and 109.1 min for the control, HEPA, SAR and SCBA ensembles. The differences were not statistically significant.
  • Early stops occurred in one control test (heart rate) and two HEPA tests (one heart rate, one rectal temperature). They also occurred in one SAR test (heart rate) and four SCBA tests (two heart rate, two fatigue).
  • End-of-test mean heart rates were 153.2, 154.8, 158.8 and 160.9 beats per minute for control, HEPA, SAR and SCBA. These were not significantly different. Mean values over the whole test were 130.2, 132.1, 134.2 and 138.5 beats per minute.
  • End-of-test mean skin temperatures were 36.40, 36.32, 36.19 and 36.33°C, and mean rectal temperatures were 38.25, 38.32, 38.22 and 38.30°C (control, HEPA, SAR, SCBA). Neither differed significantly by ensemble.
  • Mean body weight losses (corrected for water intake) were 1.328, 1.295, 1.255 and 1.379 kg for control, HEPA, SAR and SCBA. There were no significant differences.
  • The heavier SCBA increased metabolic burden, as shown by its higher oxygen consumption and carbon dioxide production in the first 20 minutes of exercise.
  • Facepiece pressures differed significantly between ensembles. Only the SAR stayed positive throughout inhalation, while the SCBA showed brief negative spikes.
  • Among subjective ratings, only perceived respirator load differed significantly: it was higher for the SCBA ensemble than for the other three (p less than 0.01).
• The authors' conclusion: The authors concluded that heavier, more protective respirators may be associated with only minimal additional physiological and subjective stress in selected low-workload asbestos abatement settings. In such settings, they considered it unjustified to exclude a highly protective respirator such as an SCBA because of presumed high stress. They also found the SAR was not associated with added burden compared with the HEPA respirator, and they called for further studies under different work conditions.
• Limitations the authors state:
  • Subjects were young, healthy and accustomed to SCBA use, so results may not apply to a less healthy workforce.
  • The work was slow, level walking for at most 2 hours. Results may not apply to climbing, crawling, or heavier and longer work.
  • The low work load and relatively high heat stress may have minimized differences between respirators.
  • Consistent but non-significant trends, such as in tolerance time and heart rate, suggested greater stress with the SCBA. The authors noted a larger study might find small but statistically significant differences.
  • The subjective rating scales were developed for this study and have no reliability or validity data.

Topics

Medical terms in this study, explained in our Lexicon: Respirator, Abatement.

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