Nicas M
Center for Occupational and Environmental Health, School of Public Health, University of California, Berkeley 94720, USA.
Am J Ind Med. 1995 Mar;27(3):317-33. doi: 10.1002/ajim.4700270302.
Tuberculosis (TB) can be transmitted to susceptible healthcare workers via inhalation of droplet nuclei carrying viable Mycobacterium tuberculosis bacilli. Several types of respiratory protective devices are compared with respect to efficacy against droplet nuclei penetration: surgical masks, disposable dust/mist particulate respirators (PRs), elastomeric halfmask respirators with high-efficiency (HEPA) filters, and powered air-purifying respirators (PAPRs) with elastomeric halfmask facepieces and HEPA filters. It is estimated that these devices permit, respectively, 42%, 5.7%, 2%, and 0.39% penetration of droplet nuclei into the facepiece. More limited data for the disposable HEPA filtering-facepiece respirator suggest that it would allow droplet nuclei penetration of 3% or less, similar to the value estimated for the elastomeric halfmask HEPA filter respirator. Because a respirator wearer's cumulative infection risk depends on the extent of droplet nuclei penetration, the cumulative risk will differ, given use of these different respirators. Hypothetical but realistic "low-exposure" and "high-exposure" scenarios are posed that involve, respectively, a 1.6% and a 6.4% annual risk of infection for healthcare workers. For the low-exposure scenario, the 10-year cumulative risks given no respirators versus surgical masks versus disposable dust/mist PRs versus elastomeric halfmask HEPA filter respirators versus HEPA filter PAPRs are, respectively, 15%, 6.7%, 0.94%, 0.33%, and .064%. For the high-exposure scenario, the 10-year cumulative risks for no respirator use versus use of the same four types of respirators are, respectively, 48%, 24%, 3.7%, 1.3%, and 0.26%. The use of disposable HEPA filtering-facepiece respirator should permit cumulative risks close to those estimated for the elastomeric halfmask HEPA filter respirator. It is concluded that when an infectious TB patient undergoes a procedure that generates respiratory aerosols, and when droplet nuclei source control is inadequate, healthcare workers attending the patient may need to wear highly protective respirators, such as HEPA filter PAPRs.
结核病（TB）可通过吸入携带活结核分枝杆菌的飞沫核传播给易感医护人员。比较了几种类型的呼吸防护设备对飞沫核穿透的防护效果：外科口罩、一次性防尘/防雾颗粒物呼吸器（PRs）、配备高效（HEPA）过滤器的弹性半面罩呼吸器以及配备弹性半面罩和HEPA过滤器的动力空气净化呼吸器（PAPRs）。据估计，这些设备分别允许42%、5.7%、2%和0.39%的飞沫核穿透进入面罩。一次性HEPA过滤面罩呼吸器的相关数据较少，不过显示其允许的飞沫核穿透率为3%或更低，与配备弹性半面罩HEPA过滤器的呼吸器的估计值相似。由于呼吸器佩戴者的累积感染风险取决于飞沫核穿透的程度，使用这些不同的呼吸器时，累积风险会有所不同。设定了假设但现实的“低暴露”和“高暴露”场景，医护人员的年度感染风险分别为1.6%和6.4%。对于低暴露场景，不使用呼吸器、使用外科口罩、使用一次性防尘/防雾PRs、使用配备弹性半面罩HEPA过滤器的呼吸器以及使用HEPA过滤器PAPRs时的10年累积风险分别为15%、6.7%、0.94%、0.33%和0.064%。对于高暴露场景，不使用呼吸器以及使用相同四种类型呼吸器时的10年累积风险分别为48%、24%、3.7%、1.3%和0.26%。使用一次性HEPA过滤面罩呼吸器应能使累积风险接近配备弹性半面罩HEPA过滤器的呼吸器的估计值。结论是，当传染性结核病患者接受产生呼吸道气溶胶的操作且飞沫核源头控制不足时，照料该患者的医护人员可能需要佩戴高度防护的呼吸器，如HEPA过滤器PAPRs。
