Summary

Several of the actions that embalmers take with dead bodies produce bioaerosols that may contain infectious pathogens. General ventilation is often the only method used to control bioaerosols in embalming labs. Nevertheless, there are no specific recommendations for applying it. Moreover, few studies have addressed occupational exposure to bioaerosols in embalming, either quantitatively (level of exposure) or qualitatively (identification and classification of risk groups). The purpose of this study was to assess embalmers’ exposure to bioaerosols in order to evaluate the potential risks to their health and examine the effect of certain factors on the behaviour of biological particles in the air.

Three embalming labs were assessed. Bioaerosol sampling was done in the air and on surfaces, using an Andersen 6-stage impactor, CIP-10M and SASS® 3100 air samplers, and Hygiena
Q-Swab™ swabs. The different types of sampling were used to count and identify culturable bacteria. Numerical concentrations of fluorescent particles (biological particles) and non-fluorescent particles and granulometric measurements (between 0.5 and 20 µm) were also done in real time near the embalmer, using a laser-induced fluorescence aerosol spectrometer (WIBS-NEO). Calculations of the air changes per hour and fluid dynamics simulations (CFD) were done in each lab. The simulations enabled us to calculate the mean age of the air in various parts of the laboratory and to assess the effect of different ventilation strategies on the concentrations of bioaerosols in the lab.

This study established that workers engaged in embalming were exposed to low levels of bioaerosols, on average, but that certain tasks were likely to generate an increase in bioaerosol concentrations near the worker. Strains of bacteria belonging to non-tuberculous Mycobacterium (Risk Group 2) were identified in two of the three labs studied. In addition to Mycobacterium, several bacteria from the Corynebacterium, Dietziaceae, Gordoniaceae. Nocardiaceae and Streptomycetaceae families were also found in the three laboratories. Finally, Streptococcus pneumoniae, a human pathogen in Risk Group 2, was cultured in samples from Laboratories A and C. The culturing of Streptococcus pneumoniae proves that bacteria from the human respiratory tract can be found in culturable state in the air of embalming labs.

Most bioaerosols have diameters of less than 4 µm (so-called respirable fraction), which means that they have a strong possibility of being deposited in the respiratory tract and a strong potential to circulate in the air of embalming rooms. Work tasks that result in a bellows effect and splashing were identified as the most emissive activities.

The ventilation rates calculated were 2.1, 10.3 and 7.9 air changes per hour (ACH), respectively, for Laboratories A, B and C. CFD simulations in the three laboratories showed that particle concentrations were highest at ventilation rates of 1 ACH. An increase from 1 to 4 ACH reduced concentrations by 28% to 67%, depending on the lab being modelled. In Laboratories A and C, a change in the mechanical ventilation by increasing the number of ACH may be a way to control bioaerosol concentrations, even though capture at source is always the preferred option. In Laboratory B, the concentrations in numbers of particles at 10.3 and 12 ACH were comparable. This seems to indicate that an increase beyond 12 ACH will not have a significant impact on concentrations. Other control methods should therefore be considered.

Considering the difficulty of identifying the existence of pathogens in dead bodies and near embalmers, the great diversity of work tasks and the uncertainty associated with the dilution of contaminants by means of general ventilation, the authors of this report recommend that, at minimum, the wearing of air-filtering respiratory protective equipment (RPE) such as a disposable filtering facepiece (N/R/P-95/99/100) or an elastomeric half-mask with P100 filter cartridges, should be considered during embalming tasks.