Imagine a fire alarm ringing in a crowded Macau casino. Perhaps no one would run. In the eyes of a punter, his baccarat game may be a matter of life and death - far more important than any fire drill. But what if it wasn't a drill? Macau takes pride in having the world's most crowded casinos. Dense crowds of adrenalin-pumped gamblers fill the halls and gaming rooms, packed around the tables and slot machines. It's a safe bet that the location of the fire exits is the last thing on their minds. The location and design of the fire exits speak volumes about a security dilemma faced by Macau's casinos. They need the doors for emergencies; but if there are too many exits, too easy to use, then petty thieves and card cheats can take advantage of them to hide and escape. So it is in the casinos' security interest to lock or obscure the exits. Take the case of the 35-year-old Casino Lisboa, known for its complicated floor plan that can feel like a maze. On the no-smoking ground floor, there are four entrances that also function as fire exits, a security guard explained. 'Don't worry,' he said reassuringly, 'there will never be a fire here.' Let's hope so. The last casino fire in Macau was on June 15, 1995, when a blaze started from a short circuit in a restaurant kitchen. Five hundred employees and gamblers were evacuated. And let us hope you are not on the third and fourth VIP floors if fire does break out. They were designed with narrow, winding corridors for maximum security, and guards are constantly on duty. 'If there is a fire now, I will tell you not to panic and instruct you to run right there,' the Lisboa guard comforted me, pointing to an exit. The 14-month-old Sands casino came up with a new solution to the security dilemma: fire exit doors are simply locked. Posing as tourists, a colleague and I surveyed the casino, pushing door after door labelled with the classic green 'Exit' sign. Soon, a security guard in a bright yellow uniform stopped us. The emergency exit doors are locked electromagnetically, he explained. 'Unless you are staff members with a special key card to swipe through the lock, you won't be able to pass through the fire exit,' he said. But as soon as sensors detect smoke, fire or heat, then computers open the doors automatically, he said. Would the doors be opened if a rat caused a panic? Or if a man flashed a gun? What happens in a power outage? 'Maybe someone in the control room will manually press a button for the doors to open,' the guard said, trying to allay our fears. What if that someone in the control room accidentally falls asleep? The guard shrugged and showed us the exit.