香港夏天，包括地鐵，食肆等，都會見到好多人用以下呢部嘢
1. 用水冷風機失去空調令人舒適之效果
空調目的係令人舒適，我地有個叫Thermal comfort zone去衡量(搵thermal comfort zone方法詳見<溫度、濕度點先算係舒適>一文)，一個人响某適當溫度及濕度下先會覺得舒服。的確水冷風機呢種Evaporative Cooling 係能夠令Dry Bulb Temperature 降低，但同時會令濕度升高，高濕度令人感覺不適，更容易令室內物件容易發霉。行內人見下圖就容易明白﹕
其實用基本邏輯諗下都知，如果水冷風機真係有用，我地洗乜用咁多錢嚟整中央冷氣？求其放堆水冷風機响度當冷氣咪得，既唔洗喉管又方便維護簡單。但可惜，好多人都搞唔清呢個世界係冇免費午餐，想要簡單地換取低溫少少冷風既時候係要用令人不適既高濕度空氣做等價交換。
2. 高濕度環境下使用完全無任何效果
都係要先掌握Psy Chart基本原理，舉個例子，假設而家某室外食肆溫度係35°C, 相對濕度係90%，如果用水冷風機"制冷"會發生乜事？
啲空氣濕度變成100%，但只換嚟1°C多少少既降溫，得不償失。
3. 最嚴重既係，用呢類灑水既水冷風機，係會令你死亡。
呢類水冷風機係散播退伍軍人病 Legionella Disease溫床。跟據衛生署衛生防護中心資料，20-45度水溫是退伍軍人病的溫床(尤其係35-42度)，正正係呢類水冷風機所用的儲水箱溫度。"Under all circumstances, the first option to be considered is to avoid, where reasonably
practicable, the use of equipment which can create a spray of contaminated water"
https://www.emsd.gov.hk/filemanager/en/content_645/COP-PLD_2021_en.pdf
4. 不乎合水務署"樓宇水管裝置手冊"要求, 於6.2.8 清楚寫明 "Water supply shall not be used for any heating, cooling or humidification purposes except with
the approval of the Water Authority.",
簡單嚟講就係違反原有供水用途，即係違法(見法例第104章<水務設施條例>
https://www.elegislation.gov.hk/hk/cap102!zh-Hant-HK?xpid=ID_1438402531424_001)
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以下係醫學上處理Legionella Disease 方法﹕
Legionella Disease (A type of Chest Infection)，係一種肺呼吸傳染病。Typical transmission via inhalation of aerosols (very small particles of water) from contaminated water or soil.
In general, people do not spread to other people, do not required isolation.
After contact with Water spray type humidifier / Water fountain / Cooling Tower / Hot Water Tanks & Heaters.
Elderly, Smoking, Lung/ Heart / Kidney, weak immune system相對易中招
Clinical features - 2-10 days after exposure, fever, low level of sodium in the blood, cough, shortness of breath, fatigue.
How to confirm: Urine Test
Treatment - Antibiotic that target Legionella, minimum 5 days
Death Rate: 70% if no treatment; 30% if with appropriate treatment
Report to Department of Health
Heater的話，可以加個Circulation Pump處理以避免某部份位置水溫太低
冷熱水管的話，加個Thermostatic Mixing Valve, 呢個嘢要盡量靠近出水端，當要用嗰陣先混合啲水，熱水管保持响60°C以上。
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以下係醫學上處理Legionella Disease 方法﹕
Legionella Disease (A type of Chest Infection)，係一種肺呼吸傳染病。Typical transmission via inhalation of aerosols (very small particles of water) from contaminated water or soil.
In general, people do not spread to other people, do not required isolation.
After contact with Water spray type humidifier / Water fountain / Cooling Tower / Hot Water Tanks & Heaters.
Elderly, Smoking, Lung/ Heart / Kidney, weak immune system相對易中招
Clinical features - 2-10 days after exposure, fever, low level of sodium in the blood, cough, shortness of breath, fatigue.
How to confirm: Urine Test
Treatment - Antibiotic that target Legionella, minimum 5 days
Death Rate: 70% if no treatment; 30% if with appropriate treatment
Report to Department of Health
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Building Services Engineers 响預防退伍軍人症呢件事上既責任主要係做好設計釐清Operation & Maintenance Precautions.
就Cooling Tower 而言，Building Services Engineering 有幾類做法可預防，舉例如下﹕
- Routine Cleaning & Disinfection, Sample Monitoring
- Bleed-off
- Chemical (Chlorinated) & Physical Treatment (Filter, Y-Strainer)
- Keep 7.5m from intake louvre
Building Services Engineers 响預防退伍軍人症呢件事上既責任主要係做好設計釐清Operation & Maintenance Precautions.
就Cooling Tower 而言，Building Services Engineering 有幾類做法可預防，舉例如下﹕
- Routine Cleaning & Disinfection, Sample Monitoring
- Bleed-off
- Chemical (Chlorinated) & Physical Treatment (Filter, Y-Strainer)
- Keep 7.5m from intake louvre
(鳴謝﹕Dr. 兔仔；Source: EMSD Code of Practice for Prevention of Legionnaires' Disease; WSD Handbook on Plumbing Installation)
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