This study evaluated the difference in respiratory protection between replaceable particulate respirators (RPRs) and powered air-purifying respirators (PAPRs), with different wearing methods during workload. Participants wore RPRs or PAPRs in the ways that workers wore them in actual workplaces. We measured the number of particles inside and outside the respiratory protective equipment (RPE) during workload for each wearing variation. The fit factor (FF) of RPRs in the workload state was significantly lower than that in the resting state, indicating inadequate respiratory protection. In contrast, the FF of PAPRs during workload was significantly lower than that at rest; however, respiratory protection was maintained. PAPR did not show a significant decrease in FF owing to the wearing variations during workload. In conclusion, PAPRs were found to be superior to RPRs in terms of respiratory protection. PAPRs are better than RPRs for workers who have to wear RPE inappropriately due to health problems.

Viruses as a whole are important pathogens. They have also been found to have a close association with certain human malignancies. Five types of herpesviruses were identified to be the causative agents in human diseases. They are herpes simplex virus (HSV) type 1, HSV-2, cytomegalovirus (CMV), Epstein Barr virus (EBV) and varicella zoster virus (VZV). These are DNA viruses capable of inducing biochemical changes in infected cells, which in most cases are triggered by virus induced or coded enzymes or proteins (Nahmias et al., 1981; Roizman, 1983). Several enzymes involved in DNA synthesis are known to be specified by some or all types of herpesvirus. A summary of these identified enzymes and the primary reactions they catalyze (Lemaster & Roizman, 1980; Blue & Stobbs, 1981; Cheng et al., 1982) is presented in Table 1.