The World Health Organization’s drinking water quality Guideline Value for fluoride is 1.5 mg / litre (WHO, 1993).
WHO emphasises that in setting national standards for fluoride it is particularly important to consider climatic conditions, volumes of water intake, and intake of fluoride from other sources (e.g. food and air).
Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. Frequent and regular physical exercise boosts the immune system and helps prevent "diseases of affluence" such as cardiovascular disease, type 2 diabetes, and obesity. It may also help prevent stress and depression, increase quality of sleep and act as a non-pharmaceutical sleep aid, help improve mental health, maintain steady digestion, regulate fertility health.