動力濾淨式呼吸防護具的應用

The Applications of the Powered Air-Purifying Respirator

簡愛倫(Ai-Lun Jian)

指導教授 ： 陳志傑

國立臺灣大學/公共衛生學院/職業醫學與工業衛生研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801450

摘要

根據台灣環境保護署近期的報告，機車尾氣排放之PM2.5濃度依據車輛品牌與型號可能高達730 μg/m3，當待速等待紅綠燈時，騎士暴露之PM2.5濃度可達到460 μg/m3，機車騎士為高PM2.5濃度暴露族群；此外，由於馬路旁較接近汽機車之排氣管，因此有較高之懸浮微粒濃度，且推車之高度接近汽機車排氣管，會使嬰幼兒暴露於高濃度PM2.5。因此，本研究目的為設計一款潔淨舒涼安全帽，能夠有效降低機車騎士暴露於PM2.5等懸浮微粒，並且增加騎士穿戴安全帽之舒適度；並且設計一款潔淨嬰幼兒手推車，避免嬰幼兒暴露於過高之PM2.5等懸浮微粒濃度，提供嬰兒適當之保護。

本研究使用市售的安全帽進行改良，提供過濾後的空氣給機車騎士，如同工業上所使用的動力濾淨式呼吸防護具。實驗中設計三種不同的供氣位置(A:頭頂後方, B:面罩側方, C: 下巴處側方)，實驗參數包含供氣流率(Qs)、外界環境風速(Ve)及不同的呼吸型態，為達成防阻外界微粒進入安全帽呼吸區，全面式安全帽下緣處以延長的擋風布圍住，並延伸遮擋頸部至胸口。以微粒凝結核計數器量測全面式安全帽內部(Cin)、外部(Cout)的微粒數目濃度，並且計算不同狀態下的保護係數(PF= Cout/ Cin)，以相同的概念應用於嬰幼兒手推車，於推車內設計三種不同的供氣位置(A:內部上方, B:推車側方, C: 坐墊處)，實驗參數包含供氣流率(Qs)、呼吸流率、CO2產生率，並以不同緊密程度之防雨罩阻擋外界氣流。

潔淨舒涼安全帽之研發部分，本研究實驗結果顯示，潔淨安全帽的保護係數會隨著供氣流率的增加而增加，且於安全帽下緣處使用擋風布，可有效增加微粒去除效率。在呼吸流率為7.5 L/min時，供氣流量從0增加到60 L/min，由位置A供氣進安全帽內部之保護係數會從1增加到752，由位置B供氣則由1增加到627，位置C從1增加到26，溫度方面，位置A可讓供氣後溫度下降約3℃，因此以供氣位置A(頭頂後方)有綜合性最佳效果。以軟殼材料作為擋風布，並於外界風速10 m/s且供氣流率小於20 L/min時，微粒去除率仍可達到98 %；測試現有市售全罩式安全帽於面罩關閉時，面體內二氧化碳濃度可於3分鐘內超過10000 ppm，若使用潔淨舒涼安全帽供氣60 L/min，濃度可降至1000 ppm以下，微粒去除率可達99 %。

潔淨嬰幼兒手推車之研發部分，由坐墊處(位置C)供氣進入嬰兒手推車內部，可有較高微粒去除效率，且能提升保護係數，搭配使用有縮口設計之緊密防雨罩並在供氣流率為60公升/分鐘時，微粒去除效率可達90 %，也可同時將呼吸區之二氧化碳濃度降至1000 ppm以下。

潔淨舒涼安全帽確實能夠有效降低騎士暴露於微粒之濃度，並且可以增加穿戴時之舒適性，以及增加機車騎士使用全面式安全帽的意願，達到衛生、舒適、安全等三方面的效果；潔淨嬰幼兒手推車能夠有效降低嬰幼兒暴露於PM2.5等懸浮微粒，並且可以降低因推車內部二氧化碳濃度累積所產生之不適情形。

關鍵字

PM2.5 ； 供氣式安全帽 ； 動力濾淨式呼吸防護具 ； 供氣式嬰兒手推車 ； 移動污染源

並列摘要

According to a recent Taiwan EPA report, PM2.5 concentration emitted from motorcycle tailpipes could exceed 730 μg/m3, depending on the brand and the model. When idling at traffic lights, motorcyclists could be exposed to PM2.5 of up to 460 μg/m3. Motorcyclists are exposed to significantly higher PM2.5 than others. In addition, because children and babies in strollers are closer to the level of tailpipes, they could be even more heavily exposed. The aim of this study was to design a full faced helmet (FFH) that provides clean air and cool temperature inside the helmet to decrease particle exposure and increase comfort for motorcyclists. And, to design clean air baby strollers that provides clean air inside the baby stroller to decrease particle exposure.

A commercial FFH was modified to receive cool and clean air in a way similar to the powered-air-purified-respirator commonly used in industrial settings. Three different clean air supply locations (A: upper rear of the head, B: zygomatic side, and C: lower chin) were designed in this study. A small wind tunnel was used to simulate the turbulence that motorcyclists might encounter while riding on the road. The operating parameters included: the supply air flow rate to the helmet (Qs), the velocity in the wind tunnel (U0) and breathing flow rate which is a combination of tidal volume (Vt) and breathing frequency (f). To minimize infiltration of aerosol outside the helmet into the breathing zone, the FFH was sealed with a long neckerchief. A condensation particle counter was used to measure particle number concentrations both inside (Cin) and outside (Cout) the FFH to calculate the protection factor (PF= Cout / Cin). Apply the same concept to infant strollers. The operating parameters included: the supply air flow rate to the stroller (Qs), three different supply air locations (A: top inside the stroller, B: side and C:cushion). The different rain covers were used to minimize infiltration of air outside the stroller into the breathing zone.

The results of cool and clean air motorcycle helmets showed that the PF of the FFH increased with increasing Qs. And the use of a long neckerchief at the lower edge of the helmet, can effectively increase the efficiency of particle removal rate. At breathing flow rate of 7.5 L/min, PF increased from 1 to 752 as Qs increased from 0 to 60 L/min with air supply at location A. PF of Location B and C increased from 1 to 627 and from 1 to 26, relatively. In addition, temperature decreased 3 ℃ with air supply at location A. With the soft shell as the sealing cloth and the wind velocity of 10 m/s, the particle removal rate can still reach 98% even if the Qs less than 20 L/min. Soft shell cloths can effectively prevent particles from flowing into the breathing zone.

The results of clean air baby strollers showed that the particle removal efficiency of the baby stroller increased with increasing Qs. Supply Air from the cushion (location C) into the stroller would achieve a higher level of protection. At Qs of 60 L/min, particle removal efficiency could reach up to 90 % with the use of highly-sealed rain cover. In addition, the CO2 concentration could be less than 1000 ppm.

In conclusion, applying a higher Qs and using an impermeable neckerchief sealed at the lower edge of the helmet or using tight rain cover outside the baby stroller would achieve a higher level of protection. The designed Cool and Clean Air Motorcycle Helmet and Clean Air Baby Strollers could decrease particle exposure, improve comfort and reduce the discomfort caused by the accumulation of carbon dioxide for motorcyclists and babies.

並列關鍵字

PM2.5 ； Air supplied helmet ； Powered-air-purified-respirator ； Air supplied baby stroller ； Mobile source

參考文獻

ASTM. (1993). Standard Test Methods for Determining Aid Change in a Single Zone by Means of a Tracer Gas Dilution (Vol. ASTM Standard E741-93). ASTM Philadelphia.

Becker, E. B. (2011). Motorcycle helmet standard comparisons-Snell M2005, DOT, BSI 6658-85 type A and EN 22/05. Retrieved from http://www.smf.org/docs/articles/mcomp2

Brühwiler, P. A., Stämpfli, R., Huber, R., Camenzind, M. (2005). CO2 and O2 concentrations in integral motorcycle helmets. Applied Ergonomics, 36(5), 625-633.

Brown, D. M., Wilson, M. R., MacNee, W., Stone, V., Donaldson, K. (2001). Size-Dependent Proinflammatory Effects of Ultrafine Polystyrene Particles: A Role for Surface Area and Oxidative Stress in the Enhanced Activity of Ultrafines. Toxicology and Applied Pharmacology, 175(3), 191-199. doi:http://dx.doi.org/10.1006/taap.2001.9240

Burton, D. J. (1989). Industrial ventilation workbook.