Morrison G C, Nazaroff W W, Cano-Ruiz J A, Hodgson A T, Modera M P
Department of Civil and Environmental Engineering, University of California, Berkeley, USA.
J Air Waste Manag Assoc. 1998 Oct;48(10):941-52. doi: 10.1080/10473289.1998.10463740.
The concentrations of contaminants in the supply air of mechanically ventilated buildings may be altered by pollutant emissions from and interactions with duct materials. We measured the emission rate of volatile organic compounds (VOCs) and aldehydes from materials typically found in ventilation ducts. The emission rate of VOCs per exposed surface area of materials was found to be low for some duct liners, but high for duct sealing caulk and a neoprene gasket. For a typical duct, the contribution to VOC concentrations is predicted to be only a few percent of common indoor levels. We exposed selected materials to approximately 100-ppb ozone and measured VOC emissions. Exposure to ozone increased the emission rates of aldehydes from a duct liner, duct sealing caulk, and neoprene gasket. The emission of aldehydes from these materials could increase indoor air concentrations by amounts that are as much as 20% of odor thresholds. We also measured the rate of ozone uptake on duct liners and galvanized sheet metal to predict how much ozone might be removed by a typical duct in ventilation systems. For exposure to a constant ozone mol fraction of 37 ppb, a lined duct would initially remove approximately 9% of the ozone, but over a period of 10 days of ozone removal efficiency would diminish to less than 4%. In an unlined duct, in which only galvanized sheet metal is exposed to the air-stream, the removal efficiency would be much lower, approximately 0.02%. Therefore, ducts in ventilation systems are unlikely to be a major sink for ozone.
机械通风建筑的送风污染物浓度可能会因风道材料的污染物排放及相互作用而改变。我们测量了通风管道中常见材料的挥发性有机化合物（VOCs）和醛类的排放率。发现某些风道内衬材料每暴露表面积的VOCs排放率较低，但风道密封填缝料和氯丁橡胶垫圈的排放率较高。对于典型风道，预计其对VOC浓度的贡献仅为常见室内浓度的百分之几。我们将选定材料暴露于约100 ppb的臭氧中并测量VOC排放。暴露于臭氧会增加风道内衬、风道密封填缝料和氯丁橡胶垫圈的醛类排放率。这些材料排放的醛类可使室内空气浓度增加，幅度高达气味阈值的20%。我们还测量了风道内衬和镀锌金属板上的臭氧吸收率，以预测通风系统中典型风道可能去除的臭氧量。对于暴露于37 ppb恒定臭氧摩尔分数的情况，有内衬的风道最初会去除约9%的臭氧，但在10天的时间里，臭氧去除效率会降至4%以下。在无内衬的风道中，只有镀锌金属板暴露于气流中，去除效率会低得多，约为0.02%。因此，通风系统中的风道不太可能是臭氧的主要汇。
