Fire hazard, did you know that the airway can also be "very injured"?

This is the 4864th article of Da Yi Xiao Hu

In recent news, there have been many cases of fires caused by negligence in the kitchen, or electric vehicles illegally charging in the corridor, causing fires, and even deflagrations and explosions. We all know that fires and explosions will produce a large amount of high-temperature, toxic and harmful smoke, which can easily cause respiratory damage or even suffocation to trapped people, seriously threatening people's lives. In fact, many places or places in life are under the shadow of flammable and explosive materials. We need to learn to protect ourselves, especially our delicate respiratory tract.

After a fire occurs, thick smoke will be produced. The characteristics of hot smoke will rise upwards, and a large amount of thick smoke will float on the upper floors, which will cause harm to people on the upper floors. Experts remind that you should never try to get out of fireworks. It is recommended to lower your body in the thick smoke, preferably crawling, and keep your head as close to the ground as possible, for example, keep it below 30 cm. If there is a sudden explosion, it is often accompanied by flames shooting into the sky, and the energy of the explosion is released, and there is a risk of inhaling high-temperature flames, dry hot air, steam, and even toxic or irritating smoke or gas.

(I) There are three main types of clinical upper respiratory tract burns:

① Mild

Burns above the throat may manifest as whitening or shedding of the oral, nasal, and pharyngeal mucosa, congestion and edema, increased secretions, burnt nasal hair, irritating cough, difficulty or pain in swallowing, etc.

② Moderate

Burns above the bronchus cause hoarseness and dyspnea. In the early stage, the sputum is thin and often contains black carbon particles. There are occasional wheezing or dry rales in the lungs. Severe dyspnea can often be improved after tracheotomy.

③ Severe

Burns extend deep into the small bronchi, and respiratory distress occurs early and is severe, often not improved by tracheotomy. Pulmonary edema and even death may occur.

2. Why is a dust explosion in a fire scene dangerous?

Dust is also generated during the explosion, especially the dust cloud formed by the mixture of combustible dust and air in a confined space. Under the action of the ignition source, the dust-air mixture formed burns rapidly and causes a chemical reaction with a sharp increase in temperature and pressure. Dust explosions are often accompanied by aluminum powder, zinc powder, aluminum processing grinding powder, various plastic powders, intermediates of organic synthetic drugs, wheat flour, sugar, sawdust, dyes, bakelite ash, milk powder, tea powder, tobacco powder, coal dust, plant fiber dust, etc. People often choose to cover their mouths and noses with clothes at the first time, and some people have the conditions to wet towels and clothes with clean water to cover their mouths and noses. For some specific metal dusts (aluminum, magnesium powder), the reaction with water will make the combustion more intense, which will increase the danger.

3. What other risks are there in case of a factory fire?

The strong acids and alkalis that may be produced by the explosion are both "killers" of the airway. The acute manifestations are mainly caused by tissue edema and congestion caused by damage to the mucosal skin tissue, and even affect lung function. Chronic effects: Long-term exposure to high concentrations can cause chronic bronchitis, gastrointestinal dysfunction and tooth erosion.

If combustion causes carbon monoxide (commonly known as coal gas) to leak in the factory, poisoning symptoms will occur. After carbon monoxide is inhaled, it will combine with hemoglobin in the blood to form carboxyhemoglobin. When the concentration of carbon monoxide in the blood reaches 0.02%, people will experience symptoms such as nervous system damage and hypoxia in 23 hours. When the indoor environmental concentration reaches 0.08%, it will take 2 hours to coma. There is also colorless hydrogen sulfide gas with the smell of rotten eggs, which also has strong respiratory irritation symptoms and may even cause "lightning" death after inhalation. Colorless ammonia with a pungent smell is an alkaline gas. When ammonia reaches a concentration of 500-700mg/cubic meter in the air, it may cause rapid death.

Author: Putuo District Central Hospital

Department of Respiratory Medicine Shi Zhaowen, deputy chief physician