The Dangers of Air Conditioning
空调的危害

By Robi Stauber ■纪冰 选注

About two-thirds of the world's population is expected to live in cities by the year 2020 and, according to the United Nations, approximately 3.7 billion people will inhabit urban areas some ten years later. As cities grow, so do the number of buildings that characterise them:1 office towers, factories, shopping malls and high-rise apartment buildings.2 These structures depend on artificial ventilation systems3 to keep clean and cool air flowing to the people inside. We know these systems by the term "air-conditioning".
Although many of us may feel air-conditioners bring relief from hot, humid or polluted outside air, they pose many potential health hazards.4 Much research has looked at how the circulation of air inside a closed environment—such as an office building— can spread disease or expose occupants to harmful chemicals.
One of the more widely publicised dangers is that of Legionnaire's disease,5 which was first recognised in the 1970s. This was found to have affected people in buildings with air-conditioning systems in which warm air pumped out of the system's cooling towers was somehow sucked back into the air intake,6 in most cases due to poor design. This warm air was, needless to say, the perfect environment for the rapid growth of disease-carrying bacteria originating from outside the building, where it existed in harmless quantities. The warm, bacteria-laden air was combined with cooled, conditioned air and was then circulated around various parts of the building.7 Studies showed that even people outside such buildings were at risk if they walked past air exhaust ducts.8 Cases of Legionnaire's disease are becoming fewer with newer system designs and modifications to older systems, but many older buildings, particularly in developing countries, require constant monitoring.
The ways in which air-conditioners work to "clean" the air can inadvertently9 cause health problems, too. One such way is with the use of an electrostatic precipitator, 10 which removes dust and smoke particles from the air. What precipitators also do, however, is emit large quantities of positive air ions11 into the ventilation system. A growing number of studies show that overexposure to positive air ions can result in headaches, fatigue12 and feelings of irritation.
Large air-conditioning systems add water to the air they circulate by means of humidifiers.13 In older systems, the water used for this process is kept in special reservoirs,14 the bottoms of which provide breeding grounds15 for bacteria and fungi which can find their way into the ventilation system. The risk to human health from this situation has been highlighted by the fact that the immune systems of approximately half of workers in air-conditioned office buildings have developed antibodies to fight off the organisms found at the bottom of system reservoirs.16 Chemical disinfectants, called "biocides", that are added to reservoirs to make them germ-free, are dangerous in their own right in sufficient quantities, as they often contain compounds such as pentachlorophenol, which is strongly linked to abdominal cancers.17
Finally, it should be pointed out that the artificial climatic environment created by air-conditioners can also adversely affect us. In a natural environment, whether indoor or outdoor, there are small variations in temperature and humidity. Indeed, the human body has long been accustomed to these normal changes. In an air-conditioned living or work environment, however, body temperatures remain well under 37℃, our normal temperature. This leads to a weakened immune system and thus greater susceptibility to diseases such as colds and flu.18

1. 随着城市的发展，代表着城市特征的建筑物也越来越多。
2. 高层公寓楼。high-rise:（建筑）多层的，高层的。
3. 人工通风设备。
4. 它们可能会给健康带来危害。
5. Legionnaire's disease: [医]军团病（一种大叶性肺炎）[因于1976年美国退伍军人大会（American Legion convention）期间首次得到确诊，故名]。Legionnaire/li:d32#ne2(r)/: 美国军团（系美国全国性退伍军人组织）成员。 6. warm air pumped...:从冷却塔压出的热空气又以某种方式抽吸回了进气孔。
7. 满布细菌的热空气和经过调节后的冷空气混合在一起，在建筑物的各个角落里循环流动。
8. air exhaust ducts: 废气管。duct:（输送液体、气体等的）导管。
9. inadvertently: 非故意的，无心的。
10. electrostatic precipitator: 静电滤尘器。
11. positive air ions: 空气中的正离子。
12. fatigue/f2#ti:g/: 疲劳，劳累。
13. humidifier: 增湿器，湿润器。
14. reservoir/#rez2vwa:(r)/: 贮液器。
15. breeding grounds: 滋生地，繁殖地。
16. 这种情况对人体健康造成的危害中最为突出的是：在空调环境下办公的员工中，有将近一半人的免疫系统中已经对系统贮液器底部的微生物产生了抗体。
17. 为了达到无菌的目的在贮液器中加入化学消毒剂，又称“杀菌剂”，当其剂量大到一定程度时也会变得危险，这是因为这类杀菌剂中往往含有五氯苯酚一类的化合物，后者与腹部癌症的发作有着极其密切的关系。
disinfectant: 消毒剂，杀菌剂；in one's own right: 凭本身的能力、实力等；pentachlorophenol/#pent2;kl0:r2#fi:n=／: [化]五氯苯酚（用作木材防腐剂、除草剂、灭菌剂等）； abdominal/*b#d=min2l/: 腹部的。
18. 这样的结果就是：人体免疫系统变得脆弱，因而更容易患上如伤风、流感一类的疾病。susceptibility: 易感性。