Rasmussen T R, Brauer M, Kjaergaard S
Institute of Environmental and Occupational Medicine, University of Aarhus, Denmark.
Am J Respir Crit Care Med. 1995 May;151(5):1504-11. doi: 10.1164/ajrccm.151.5.7735607.
Nitrous acid (HONO) is formed both indirectly from the reaction of nitrogen dioxide (NO2) with water on indoor surfaces, and directly during combustion. This gaseous pollutant may be a previously unrecognized causal factor in assessments of nitrogen oxide exposure effects. The present study is the first attempt to evaluate exposure effects of HONO on the human airways and the mucous membranes of the eyes and nose. Fifteen healthy adult nonsmokers were exposed for 3.5 h in a double-blind, balanced protocol to clean air, 77, and 395 ppb HONO. Each exposure was preceded by a 1-h baseline measurement period, and exposures were separated by 1 wk. There was a 10-min exercise period during exposure. Effects measurements included assessment of bronchial reactivity, measurement of specific airway conductance, spirometry, acoustic rhinometry, nasal lavage, tear-fluid cytology, a CO2 eye-provocation test, evaluation of eye redness, and subjective sensations. Effects of HONO exposure on the eyes were found as exposure-related changes in tear-fluid cytology. In particular, the number of squamous cells increased by 20, 67, and 80% following exposure to clean air, 77, and 395 ppb HONO, respectively (p = 0.004). Possible indications of exposure effects on sensitivity to CO2 eye provocation and on specific airway conductance were also measured. For specific airway conductance there was an approximate 10% decrease in conductance following exercise in association with HONO exposure, compared with a 2% decrease with clean air (p = 0.038).
亚硝酸（HONO）可通过二氧化氮（NO2）与室内表面的水反应间接形成，也可在燃烧过程中直接形成。这种气态污染物可能是氮氧化物暴露效应评估中一个此前未被认识到的致病因素。本研究首次尝试评估HONO对人体气道以及眼鼻黏膜的暴露效应。15名健康的成年不吸烟者按照双盲、平衡方案，分别暴露于清洁空气、77 ppb和395 ppb的HONO环境中3.5小时。每次暴露前有1小时的基线测量期，暴露之间间隔1周。暴露期间有10分钟的运动时段。效应测量包括支气管反应性评估、特定气道传导率测量、肺量计测量、鼻声反射测量、鼻腔灌洗、泪液细胞学检查、二氧化碳眼激发试验、眼红评估以及主观感受。发现HONO暴露对眼睛的影响表现为泪液细胞学检查中与暴露相关的变化。具体而言，暴露于清洁空气、77 ppb和395 ppb的HONO后，鳞状细胞数量分别增加了20%、67%和80%（p = 0.004）。还测量了暴露对二氧化碳眼激发试验敏感性和特定气道传导率影响的可能指标。对于特定气道传导率，与清洁空气暴露时运动后传导率下降2%相比，HONO暴露时运动后传导率下降约10%（p = 0.038）。
