Health experts have warned the people to switch off gas room heaters before going to bed to avoid risks of causing fires or suffocation. Shaikh Zayed Hospital Chairman, Dr Zafar Iqbal told APP on Sunday that the public should observe safety measures while using gas room heaters to avoid mishaps which could lead to death. Treatment of the gas affected patients was a very complicated process, he added. He said that before going to bed people should ensure that room heaters were properly switched off and gas supply should be closed at the source to avoid leakages. Jinnah Hospital Medical Superintendent, Dr Fazal Ur Rehman said that majority of people used gas heaters in almost air tight rooms during the winter season, which resulted in gas poisoning and could also lead to fatal casualty due to absence of adequate fresh oxygen intake. He stressed that a window or a ventilator should be kept open to allow oxygen to continue circulating in the room. Former managing director of Heavy Electrical Complex, Engineer Ashique Ali said that combustion of natural gas produced carbon monoxide which was hazardous to life as it destroyed red blood cells which maintained adequate oxygen level in blood. Dr Zafar said that low levels of blood oxygen adversely affected the entire human body, especially the brain, liver, kidney, muscles and the living tissues.