Drinking water is one of the best ways to replace the fluid lost through heat, according to Cindy Lam Lo-kuen, assistant professor of the family medicine unit at the University of Hong Kong. However, she advises that people should try to avoid concentrated fruit juice, soft drinks and beer, which she says can do more harm than good because their water concentration can be even lower than that in the blood. You can wash your face and body with tap water to cool down. But do not use ice water, as it will cause blood-vessel constriction and reduce the heat-loss function. Avoid going outdoors or doing strenuous exercise when the temperature climbs over 33 degrees Celsius as the body has difficulties releasing heat in such weather. Make sure you drink one litre of water if you are to do an hour's strenuous exercise or outdoor work in the heat. You can also add salt to the water. If you don't have an air conditioner at home, keep windows wide open and put household items away to improve ventilation.