When a high-rise building is on fire, should you run up or down? Don't wait until tragedy happens before you know it.

Expert of this article: Yang Chao, PhD in Chemistry, University of Chinese Academy of Sciences

This article was reviewed by Liu Yongjia, Deputy Chief of Harbin Forest Fire Brigade and Director of Fire Fighting and Rescue Command

With the rapid development of urban construction

There are more and more high-rise buildings in cities.

Most people’s work and life

In buildings or high-rise buildings

Due to the large flow of people and different lifestyles

There are many fire hazards

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A high-rise building in Dalian, Liaoning

——Triumph International Building

Fire occurred last year

The fire department dispatched 24 fire stations

Nearly 400 firefighters

More than 7 hours

The fire at the Kaixuan International Building was put out.

The fire is merciless

Once a high-rise building catches fire

The first reaction of many people is to run.

But in the high-rise

Should I run up or down?

Why does a high-rise building catch fire?

Why is fire fighting and rescue work so time-consuming and laborious?

Image source: Photographed by the author

Today is

National Disaster Prevention and Reduction Day (May 12)

Emphasis on disaster prevention and mitigation

Protecting the bottom line of life

I hope you don't need these first aid tips

But you must know

Why is it difficult to rescue people when a high-rise fire breaks out?

Fires in high-rise buildings are generally caused by violations of safety regulations in production and life, careless use of fire/improper use of electricity, natural phenomena, arson, etc.

Why is it difficult to rescue a fire in a high-rise building? Compared with a fire in an ordinary low-rise building, a fire in a high-rise building has the following characteristics:

1. Chimney effect increases oxygen circulation

The internal structure of a high-rise building is relatively complex, and generally there will be multiple stairwells, elevator shafts, exhaust ducts and other vertical shafts, which have the characteristics of chimneys. After a building catches fire, the hot air inside the building and the cold air outside the building form a density difference, thereby forming a pressure difference. The pressure difference forces the hot air in the building to flow upward along the vertical pipes and then be discharged from the exhaust vents on the top of the building. At this time, a negative pressure area will be formed near the fire point, and the low-temperature and low-density fresh air outside the building will be sucked in from the bottom of the building. Such air flow will bring more fresh air into the building, which is the chimney effect. Oxygen continues to flow in, thereby fueling the fire. The higher the height of the high-rise building, the more obvious the chimney effect.

Image source: Photographed by the author

2. The wind is strong at high altitudes and the fire spreads quickly

Tests conducted by the Shanghai Fire Department show that if a building 100 meters high catches fire, the fire can spread from the bottom through the vertical shaft to the top floor within 30 seconds, and the entire building can instantly become a "three-dimensional fire scene". The wind speed at 90 meters in a high-rise building can reach 15 meters per second, and the higher the floor, the greater the wind speed, which accelerates the spread of the fire.

3. Limited by the height of the lifting vehicle

At present, the height of domestic aerial fire trucks is about 50 meters, and the height of some vehicles can reach 80 meters. The maximum operating height of aerial fire trucks produced and used in the world is 110 meters, while the floor height of residential and commercial buildings is generally 3-4 meters. Therefore, aerial fire trucks can generally only rescue floors below the 14th floor, and rescue work on fires on higher floors will be restricted.

4. Firefighters are physically limited

When a fire occurs, the power system is shut down or fails, and electrical equipment such as elevators cannot be used. Although well-trained firefighters can walk to the 12th floor or higher of a building, they still need to carry personal protective equipment and fire-fighting and rescue equipment to climb stairs for rescue. These additional weights of at least 20 kilograms will greatly consume the firefighters' physical strength and reduce rescue efficiency.

5. Difficulty in evacuating damaged and trapped people

According to calculations, if there are 120 people on each floor and only one evacuation staircase, if a fire occurs, it will take 19 minutes to evacuate all people on the 15th floor to the ground, 39 minutes for a 30-story building, and more than an hour for a 50-story building. In actual fire situations, it will take even longer. The most efficient and safe time to escape after a fire is 7 minutes, so there are great safety hazards in escaping from a high-rise building fire.

If a high-rise building is on fire, should you run upstairs or downstairs?

If you are in a high-rise building, how can you save yourself after a fire? Here are four escape suggestions:

▶When encountering a fire, stay calm, call the fire alarm 119, explain the cause, location, and size of the fire, analyze the fire situation clearly, and escape quickly through a safe passage.

▶Trapped people below the 10th floor can escape immediately through the evacuation passage. If the fire is not big, you can wet the bedding or blanket with water and wrap it around your body. At the same time, protect your mouth and nose with a wet towel and move forward by bending over to prevent choking by thick smoke and reduce the impact of toxic gases produced by combustion. If the fire is big, do not blindly choose to jump off the building because of excessive excitement. You must follow the 7-meter jumping principle - as long as it is higher than 7 meters, don't expect to escape by jumping off the building.

▶For those who live on the 10th floor or above, if the fire is not big and the fire is below their location, they can first move to the rooftop, enter the building of the adjacent unit from the rooftop, and take the elevator to escape to the outside; if the fire is large, due to the "chimney effect", they must not escape through the corridor, and should find a safe and conspicuous balcony or window to wait for rescue by firefighters.

Image source: Photographed by the author

▶Buildings over 100 meters tall usually have refuge floors, where people can take refuge after a fire. If all safety passages are cut off, the bathroom can also be used as a relatively safe place to take shelter. In an emergency, you can also close the bathroom doors and windows, seal the gaps, open all faucets, and lie in a bathtub if there is one to take shelter temporarily, buying time for firefighters to rescue.

How to prevent fire?

Since rescue is difficult after a high-rise building catches fire, prevention is the key factor. Preventive measures for high-rise building fires can start from the following points:

Strengthen the management of fire prevention facilities in high-rise buildings, regularly test and inspect automatic fire alarm systems, fire extinguishing systems, emergency broadcast systems and other linkage control equipment, and ensure that high-level fire water tanks, fire pump outlet pipe valves, and valves on sprinkler fire extinguishing system pipelines are always open.

Strengthen the fire safety management of buildings, ensure that evacuation passages and emergency exits in buildings are unobstructed at all times, and normally closed fire doors should be kept closed.

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Enhance fire safety awareness to avoid fires caused by careless use of fire/improper use of electricity in violation of safety regulations in production and life, and at the same time improve the ability to deal with emergencies and self-rescue in fires.

Strengthen the quality control of decoration materials, use non-combustible or flame-retardant materials to decorate the interior of buildings, and avoid using combustible or flammable materials or materials that produce toxic and harmful gases after combustion for decoration.

When on a business trip or traveling, the first thing you should do when staying in a high-rise hotel is to check around and memorize the emergency exit layout. If you have time, you can also simulate walking through the escape route so that in the event of an emergency such as a fire, you can escape quickly.

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