People who have worked their way up to that room at the top are likely to have a sense of daring - so heights rarely unnerve them. But they also realise that fire-safety measures are an ever-present concern. As more high-rises take their place along the Hong Kong skyline, fire safety has emerged as a distinct engineering discipline that developers, government, property management companies and others turn to when construction reaches for the skies. Fire-safety engineers are the people on whom architects and fellow engineers depend in ensuring that safety appliances, evacuation routes and alarms are all in the right place in the event that the worst happens. 'In Hong Kong, the only way to build is up, so we have good reason to use fire-safety engineering here as, especially in terms of density, we must have the highest concentration of high-rises in the world,' said Richard Yuen Kwok-kit, associate professor at City University of Hong Kong's Faculty of Science and Engineering. A unique feature of Hong Kong high-rises is that on every 25th storey a floor must be set aside solely for evacuation purposes and as a control centre for firefighters and other emergency personnel in case of an emergency. This ensures that, in the event of a fire, those who have to evacuate from the upper floors get a chance to rest or receive treatment. The Fire Safety Code enshrines the rules for fire prevention, evacuation, and maintenance that are followed by architects, engineers and fire officials, and provides guidelines and measures for fire prevention, evacuation and maintenance. As well as legal aspects, experts take account of mass psychology when they design evacuation and safety procedures. Computer simulations help engineers and fire officers identify crowd behaviour patterns in times of emergency, and software is used to predict smoke movement (smoke is often the biggest killer in fires). Requirements at residential buildings differ from those at commercial premises, but the main concern is always the safety and preservation of life. 'Research is still ongoing in areas such as fire doors and the movement of smoke,' Dr Yuen said. 'When it gets down to the micro levels of a fire door, there will be a gap if there is enough pressure. Research into this looks at how gaps affect the mechanism for stopping smoke flow.' As sky-high dwellings gain in popularity among the lifestyle-conscious, designers, engineers and fire-safety officials will keep stepping up their efforts to ensure that flames and smoke cause minimal harm, and people can escape safely in an emergency.