TAILIEUCHUNG - IELTS to sccess part 5
Tham khảo tài liệu 'ielts to sccess part 5', ngoại ngữ, toefl - ielts - toeic phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | showed lhal even people inside such buildings were al risk if they walked past air exhaust ducts. 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. Cigarette smoke is also carried from room to room by some air-conditioning systems bringing with it the attendant risks of passive smoking. The past few years have seen a lot of studies into passive smoking the smoke breathed in by non-smokers living or working near smokers. In japan a survey of medical records showed that women whose husbands do not smoke are half as likely to acquire lung cancer as those who are married to smokers. Research into passive smoking in an office setting demonstrated similar risks for non-smokers working for many years next to smokers. Smoky air circulated by the air-conditioning system of the average office according to an Australian study caused non-smokers to breathe in the equivalent of three cigarettes in one day of work. I he ways in which air-conditioners work to dean the air can inadvertently cause health problems loo. One suc h way is with the use of an electrostatic precipitator which removes dust and smoke particles from the air. What precipitators also do however is emit large quantities of positive air ions into the ventilation system. A growing number of studies show that overexposure to positive air ions can result in headaches fatigue and feelings of irritation. Large air-conditioning systems add waler to the air they circulate by means of humidifiers. In older systems the water used for this process is kept in special reservoirs the bottoms of which provide breeding grounds 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 .
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