Endotoxins are components of the outer membrane of certain bacteria that can become airborne during certain aerosol-generating work activities and cause adverse effects on workers health. Filtration is the sampling method recommended by the EN 14031 standard for endotoxin measurements in workplace atmospheres. However, there are still differences in terms of practice regarding certain parameters of the measurement method. Thus, the storage of samples, the method of endotoxin extraction from the filter, and the type of filter are some parameters that still need to be studied to improve endotoxin recovery. For this purpose, laboratory experiments based on the generation of an endotoxin aerosol coming from 3 Gram-negative bacteria were investigated. This complex bioaerosol covers endotoxin concentrations from ~ 10 to ~ 10(exposant 4) EU/m3. Our results show that a better recovery of endotoxins is achieved using 5 mL of pyrogen-free water, especially for glass fiber filters, with no change when reducing the agitation to 20 minutes. Except for polyvinylchloride, the type of filter (polycarbonate, Teflon, or glass fiber) does not have a great influence on the concentrations measured. However, PVC filters systematically gave a lower endotoxin concentration than the others. Finally, storage of the samples at room temperature is possible for up to 8 days after sampling. These improvements make the results of the endotoxin concentration more robust and will help to make this measurement method more readily usable, especially with the simplification of the protocol steps and storage, providing a greater flexibility for analysts.
