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  1. Most people spend 80-90% of their time indoors, so the quality of our indoor environment is important both in terms of our health and our work efficiency.  The main factors that impact on the indoor environment are temperature, humidity, air movement and exchange rate, ventilation and particle, biological and gaseous pollutants.  As the use of air conditioning systems is increasing and so are the health issues associated with poor indoor air quality, such as e.g. sick building syndrome (SBS) which has an array of symptoms, including nausea, fatigue, eye, nose or throat irritation, allergies, ‘flu -like symptoms and increased asthma attacks.[1] Air conditioning, an increasingly common feature in modern indoor environments can play an important role in mediating many of these factors. This importance is highlighted by one study in the USA, which demonstrated that, in hot weather, people with air conditioning were 10.2% less likely to die than those without.[2]  Pollutants in air conditioning systems include dust mites, bacteria or toxic substances or particles from the outdoor environment which can also enter the indoor environment via doors and windows.[3] Chinese studies of mites in the dust of air-conditioner filters (MACF) have shown that air samples from shopping malls, hotels and households contained significantly higher concentrations of dust mites after the air-conditioning had been running for an hour.[4]  MACF concentrations were also affected by temperature and latitude, the type and the age of the air conditioner and the time it was in use. Wall and window based units are more likely to have a higher MACF density than floor based units, and MACF concentration was also affected by the cleaning and/or filter replacement interval.[5] Air conditioners can also harbour bacteria such as Legionella, that can cause two illnesses: Legionnaires disease (similar to pneumonia) and Pontiac Fever, a similar but much milder disease.[6] Legionella bacteria can grow in the water cooling towers used in the air-conditioning units of large buildings.[7] They are spread via water droplets small enough for inhalation, infecting people who inhale them.[7] Evaporative air conditioners, commonly found in domestic use, may also harbour Legionella bacteria and should therefore be regularly cleaned and left clean and dry when not in use.[8] The free living amoebae Acanthamoeba, normally found in air, soil and water, has also been found in air-conditioning units. Acanthamoeba can cause serious health conditions such as primary amoebic meningoencephalitis, granulomatous amoebic encephalitis and chronic amoebic keratitis, and pose a potential health risk worldwide.[9] [10] Air conditioner filters have been shown to contain poly-brominated diphenyl ethers (PBDEs) which have been shown to have adverse effects on the thyroid and liver of animals, [11] [12] as well as potential carcinogenic effects in humans.[12] The largest supermarket (24,000 m2) in Hangzhou, China, which utilises both central ventilation and air conditioning systems, was used for a long-term air sampling investigation to detect the concentration of airborne polycyclic aromatic hydrocarbons (PAHs), which are probable human carcinogens. Total levels of PAHs increased when the central ventilation and air conditioner systems were used together when compared to a time when the air conditioner was switched off. Therefore, overall, air conditioning reduces levels of PAHs. [13] Although air conditioning is designed to reduce the levels of external particulate pollutants and ozone, these substances can accumulate in filters, and levels of indoor pollutants, e.g. if people smoke in the building, can be increased.[14] Humidity levels are commonly low in air-conditioned buildings and ideally should be routinely monitored. Long term exposure to a very dry atmosphere can cause itching that may develop into contact dermatitis, elevation of the specific gravity of urine, exacerbations or skin complaints such as atopic dermatitis and cause general surface roughness to the skin.[15] [16] A study of 10 drivers who used their car air conditioner for more than an hour a day for 6 months showed a greater predisposition to respiratory complaints – mild airflow disturbances then the control group.[17] Air conditioning systems can help to decrease the level of particulate pollutants and ozone in our indoor environments and can prevent heat-related illness in hot weather. However the filters designed to perform this role have the potential to absorb toxic substances and harbour dust mites which can increase health risks, particularly for asthma and allergy sufferers. Water cooling towers used in air conditioning systems of large buildings are a favourable environment for pathogens, which can infect those inside. Finally, dry air can result from the use of air conditioners, which can have adverse effects on skin. Risks can be reduced by controlling humidity and routinely cleaning filters, as well as regular opening of the windows for fresh air inflow. But increasing time spent outside and especially outside the cities is definitely the best piece of advice still available in this world.   [1] Joshi, S. (2008). The sick building syndrome. Indian Journal Of Occupational And Environmental Medicine, 12(2), 61. [2] O'Neill, M. (2005). Disparities by Race in Heat-Related Mortality in Four US Cities: The Role of Air Conditioning Prevalence. Journal Of Urban Health: Bulletin Of The New York Academy Of Medicine, 82(2), 191-197. [3] Yu, B., Hu, Z., Liu, M., Yang, H., Kong, Q., & Liu, Y. (2009). Review of research on air-conditioning systems and indoor air quality control for human health. International Journal Of Refrigeration, 32(1), 3-20. [4] Zhan, X., Li, C., Xu, H., Xu, P., Zhu, H., Diao, J., Zhao, B. (2015). Air-conditioner filters enriching dust mites allergen. International Journal of Clinical and Experimental Medicine, 8(3), 4539–4544. [5] Wu, J., Liu, Z., Ran, P., & Wang, B. (2009). Influence of environmental characteristics and climatic factors on mites in the dust of air-conditioner filters. Indoor Air, 19(6), 474-481. [6] Legionella | Signs and Symptoms | Pontiac Fever | Legionnaires | CDC. (2017). Retrieved 13 September 2017, from [7] Legionella | Causes and Transmission | Legionnaires | CDC. (2017). Retrieved 13 September 2017, from [8] Minimising the risk of a Legionella infection at home. (2017). Retrieved 13 September 2017, from [9] Astorga, B., Lorenzo-Morales, J., Martín-Navarro, C., Alarcón, V., Moreno, J., & González, A. et al. (2011). Acanthamoeba Belonging to T3, T4, and T11: Genotypes Isolated from Air-Conditioning Units in Santiago, Chile. Journal Of Eukaryotic Microbiology, 58(6), 542-544. [10] Marciano-Cabral, F., & Cabral, G. (2003). Acanthamoeba spp. as Agents of Disease in Humans. Clinical Microbiology Reviews, 16(2), 273-307. [11] Besis, A., Katsoyiannis, A., Botsaropoulou, E., & Samara, C. (2014). Concentrations of polybrominated diphenyl ethers (PBDEs) in central air-conditioner filter dust and relevance of non-dietary exposure in occupational indoor environments in Greece. Environmental Pollution, 188, 64-70. [12] ATSDR - ToxFAQs™: Polybrominated Biphenyls (PBBs). (2017). Retrieved 13 September 2017, from [13] Lv, J., & Zhu, L. (2013). Effect of central ventilation and air conditioner system on the concentration and health risk from airborne polycyclic aromatic hydrocarbons. Journal Of Environmental Sciences, 25(3), 531-536. [14] Increased Use of Air Conditioning | Indoor Air Quality (IAQ) Scientific Findings Resource Bank (IAQ-SFRB). (2017). Retrieved 13 September 2017, from [15] Chou, T., Lin, K., Sheu, H., Su, S., Lee, C., & Guo, H. et al. (2006). Alterations in health examination items and skin symptoms from exposure to ultra-low humidity. International Archives Of Occupational And Environmental Health, 80(4), 290-297. [16] Ohno, H., Nishimura, N., Yamada, K., Shimizu, Y., Iwase, S., Sugenoya, J., & Sato, M. (2013). Effects of water nanodroplets on skin moisture and viscoelasticity during air-conditioning. Skin Research And Technology, n/a-n/a. [17] Khaliq, F., Sharma, S., & Tandon, O. (2006). Pulmonary functions in air conditioner users. Indian J Physiol Pharmacol, 50(1), 67-72. Retrieved from
  2.   What is healthy fluoride intake Fluoride is a mineral, and when present at the right level, it has long been believed to have two beneficial effects: preventing tooth decay and contributing to healthy bones.[1] Adding fluoride to drinking water (fluoridation) to prevent dental caries has often been regarded as one of the top ten public health achievements of the 20th century. In the US, fluoride is added to about 70% public drinking water. However, the benefits of fluoridation have come under recent scrutiny, due to the reliance on evidence from old statistical interpretations, rather than the up-to-date real-world evidence.[2] Reductions in dental caries attributable to fluoridation were initially estimated at approx. 50%-60%.[3] More recent estimates are much lower, 18%--40%, and are thought to probably be lower still, as the widespread use of oral hygiene in general terms has been improving and is now probably the most important factor for reducing dental caries.[3] Some studies have shown limited differences in tooth decay rates between countries with fluoridated and non-fluoridated water, or between states that fluoridate a high versus low percentage of their water.[4] [5] Higher levels of fluoridation of drinking water have been shown to correlate with an increased incidence of fluorosis, an abnormal condition caused by the excessive intake of fluorides, characterized in children by discolouration and pitting of the teeth. One meta-analysis suggested that, for a fluoride level of 0.7 ppm, the percentage of participants with “fluorosis of aesthetic concern” was approx. 12%. This rose to 40% when looking at fluorosis of any kind.[2] Numerous studies have shown that excessive fluoride intake in infancy and early childhood can have a wide array of devastating health effects. These outcomes can be irreversible and include structural and functional changes to the central nervous system that can lead to memory, learning and intellectual deficits.[6] Harvard researchers showed that children who live in areas where the level of fluoridation is higher had a “significantly lower IQ than those in low fluoride areas”, further showing a direct link with fluorosis (a consequence of high levels of fluoride in drinking water) and decreased IQ levels, stating that “the results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment”.[7] There have been literally hundreds of human and animal studies that link excessive fluoride to changes in the brain.[8] These adverse effects include reductions in communication pathways,[9] impaired defence systems[10] and damage to specific regions.[11] Given the harmful side effects associated with excessive exposure to fluoridated water, it is therefore wise to investigate the level of fluoridation of your own drinking water, particularly in homes with children, whose development may be affected. Those living in areas with fluoridated mains water may wish to consider the use of water filters or bottled water as an alternative source of drinking water, particularly for children.   [1] Smith, GE. (1985) Fluoride, teeth and bone. Med J Aust. 143(7). 283-6. [2] Iheozor-Ejiofor, Z. et al. (2015) Water fluoridation for the prevention of dental caries. Cochrane Database Syst Rev. [epub ahead of print] doi: 10.1002/14651858 [3] CDC (2001) Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States. Retrieved May 2016 from, [4] Ismail, AL. et al. (1993) Should the drinking water of Truro, Nova Scotia, be fluoridated? Water fluoridation in the 1990s. Community Dent Oral Epidemiol. 21(3). 118-25. [5] Franzolin Sde, O. et al. (2010) Epidemiology of fluorosis and dental caries according to different types of water supplies. Cien Saude Colet. 15. 1841-7. [6] Khan, SA. et al. (2015) Relationship Between Dental Fluorosis and Intelligence Quotient of School Going Children In and Around Lucknow District: A Cross-Sectional Study. J Clin Diagn Res. 9(11).  [epub ahead of print] doi: 10.7860/JCDR/2015/15518.6726. [7] Choi, AL. et al. (2012) Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis. Environ Health Perspect. 120(10). 1362-8. [8] Niu, R. et al. (2015) Effects of fluoride on microtubule ultrastructure and expression of  Tubα1a and Tubβ2a in mouse hippocampus. Chemosphere. 139: 422-7. [9] Long, YG. et al. (2002) Chronic fluoride toxicity decreases the number of nicotinic acetylcholine receptors in rat brain. Neurotoxicol Teratol. 24(6). 751-7. [10] Niu, R. et al. (2016) Changes in Liver Antioxidant Status of Offspring Mice Induced by Maternal Fluoride Exposure During Gestation and Lactation. Biol Trace Elem Res. 172(1). 172-8. [11] Zhang, M. et al. (2007) Effects of fluoride on the expression of NCAM, oxidative stress, and apoptosis in primary cultured hippocampal neurons. Toxicology. 236(3). 208-16.
  3. What is healthy water consumption Water is a major and vital constituent of the human body. The average adult’s body is about 60% water, whilst an infant’s is 75% and an elderly person’s 55%. Even a few days without water can be fatal. The roles of water in the body are wide and far-reaching and include body temperature regulation, participation in many biochemical reactions at cell level, the flushing away of waste products, lubrication of joints and the moistening of tissue, such as the eyes, nose and mouth. It is also the solvent for distributing nutrients and minerals throughout the body. General organ function is enhanced by the presence of water, which also helps the muscles (including the heart) work with less stress.[1] There is increasing evidence to suggest that mild dehydration can promote the development of many chronic diseases. These include:[2] Exercise-induced asthma Urolithiasis Urinary tract infections Constipation Hypertension Fatal coronary heart disease Venous thromboembolism Cerebral infarct Bronchopulmonary disorders Hypertonic dehydration in infants Hyperglycaemia in diabetic ketoacidosis Mild dehydration also impairs important aspects of cognitive function, including alertness, concentration and short term memory.[3] The regulation of water balance is a very precise and complex process. In a healthy adult, an imbalance of just 1% is corrected by the body within about a day. However, in young children and the elderly, regulation is not so efficient, making them far more susceptible to dehydration and its accompanying health complications.[4]     The most common causes of dehydration are fever, heat exposure, excessive exercise, vomiting diarrhoea, and increased urination due to infection. Diseases such as diabetes can increase urine output, making diabetics more predisposed to dehydration.[5] The symptoms of moderate dehydration include increased thirst, dry mouth, headache and dizziness. As the body becomes more dehydrated, the urine becomes darker in colour (deep yellow or amber) and this in itself may be a useful indicator of dehydration. Severe dehydration can quickly become very serious, if not life threatening, particularly in the very young and the elderly. The exact water requirements of an adult are difficult to define, as there are many influencing factors. These include the climate in which we live and our level of physical activity etc. It is estimated that an average sedentary adult requires about a litre and a half of water per day. Mineral water is a preferable source of hydration compared to calorie-laden sweet drinks, beer, tea or coffee, which all may have diuretic effects, in addition to being associated with metabolic syndrome, fatty liver disease and obesity to name a few.[6] Soup is also a good source of water, as are fruit and vegetables, which are generally high in water content. Despite some claims, there is only limited evidence to suggest that drinking water has a direct effect on weight.[7] However water is known to aid the digestive process, and drinking water as a substitute for sugary or “diet” drinks, which are both associated at least with weight gain and adverse metabolic changes.[8] Thus the benefits of staying hydrated are clear - reduced risks of various health conditions, improved cognitive function, and the potential to aid weight loss if water is used as a substitute for other calorie-laden soft drinks. These positive effects may be most pronounced in those most susceptible to dehydration and care should therefore be taken in these populations when it comes to keeping topped up with enough water every day.   [1] Popkin, BM. et al. (2010) Water, hydration and health. Nutr Rev. 68(8). 439-58. [2] Manz, F. & Wentz, A. (2005) The importance of good hydration for the prevention of chronic diseases. Nutr Rev. 63(6 pt 2). S2-5 [3] Ritz, P. & Berrut, G. (2005) The importance of good hydration for day-to-day health. Nutr Rev. 63(6 pt 2). S6-13 [4] Jéquier, E. & Constant, F. (2010) Water as an essential nutrient: the physiological basis of hydration. Eur J Clin Nutr. 64(2). 115-23. [5] Adam, P. (1997) Evaluation and management of diabetes insipidus. Am Fam Physician. 55(6). 2146053. [6] Harvard T.H. Chan School of Public Health. (2015) Sugary drinks. Retrieved April 2016, from [7] Muckelbauer, R. et al. (2013) Association between water consumption and body weight outcomes: a systematic review. Am J Clin Nutr. 98(2). 282-99. [8] Vartanian, LR. et al. (2007) Effects of soft drink consumption on nutrition and health: a systematic review and meta-analysis. Am J Public Health. 97(4). 667-75.