Li Yanming, Deputy Director of the Department of Respiratory and Critical Care Medicine at Beijing Hospital, Ministry of Health, member of the Infection Group of the Chinese Medical Association's Respiratory Disease Branch, and youth committee member of the Chinese Medical Association's Internal Medicine Society. His research focuses on respiratory infections and elderly lung infections. He has conducted in-depth research in areas such as ventilator-associated pneumonia, pharmacokinetic/pharmacodynamic studies of antibacterial drugs, elderly lung infections, systemic fungal infections, and catheter-related infections. He has been involved in multiple municipal, ministerial, and national-level scientific research projects and has published over 10 papers in core journals. He was recognized as an Advanced Individual in the Capital's Prevention and Control of Atypical Pneumonia and has won the Third Prize of the Beijing Science and Technology Award.
Yang Fude, Chief Physician, Professor, and Graduate Supervisor at Peking University Teaching Hospital — Beijing Huilongguan Hospital, Director of the Clinical Psychopharmacology Research Laboratory, Director of the National Drug Clinical Trial Base, Deputy Secretary of the Party Committee, and President. Director of the Beijing Psychological Assistance Hotline (Head of Expert Group), Director of the Expert Committee for the Management of Severe Mental Illness Treatment in Beijing, Director of the Beijing College Students' Psychological Crisis Prevention and Intervention Guidance Center, Director of the Beijing Psychological Crisis Research and Intervention Center, and Director of the WHO Collaborating Center for Research and Training in Mental Health Crisis.
Since 2013, people have gradually become familiar with a term — hazy weather; another very popular term is PM2.5, which at its peak reached 993 micrograms per cubic meter, far exceeding safe levels. During the continuous hazy days in Beijing, the number of patients visiting the respiratory department has increased significantly. Today, authoritative expert Li Yanming from the Department of Respiratory and Critical Care Medicine at Beijing Hospital will talk about the impact of hazy weather on human health.
What is hazy weather?
What is hazy weather? Many people feel that fog and haze are similar, but they are actually two completely different phenomena.
Fog is a natural phenomenon that occurs when the air humidity is very high. Its composition is water, and it dissipates when the sun comes out. It has no physical impact on the human body.
Haze, on the other hand, is a form of environmental pollution caused by human activities. Its composition consists of fine particulate pollutants that do not disappear as humidity decreases. Haze can affect our bodies, especially the respiratory system, causing discomfort and exacerbating some underlying illnesses in patients.
What causes haze?
What is the main cause of haze? It is PM2.5. PM2.5 is the most important fine particulate matter in haze, resulting from human activities. Its components may include coal combustion byproducts, nitrates, sulfates, biofuels, industrial emissions, etc., but it mainly comes from the following four sources:
The first is vehicle exhaust. There are now more than 5 million vehicles in Beijing, especially diesel vehicles, which release large amounts of exhaust every day.
The second is dust. Sometimes Beijing resembles a large construction site, and the dust from these sites also becomes a major contributor to haze.
The third is industrial emissions. Some manufacturing industries, such as thermal power plants, steel mills, and cement plants, also produce large amounts of industrial waste gas daily.
The fourth is northern coal. What do we rely on for heating? Coal. But the burning of coal is a very important cause of haze.
What is PM2.5?
So what does PM2.5 refer to? It refers to the diameter of particles. PM2.5 consists of particles with a diameter of less than or equal to 2.5 micrometers. PM10 refers to airborne particles with a diameter of less than or equal to 10 micrometers.
Our respiratory tract is like a large tree branch, branching off into smaller and smaller parts. So, if you inhale air containing many of these particles, they will deposit in different airways and bronchi based on their size. The smaller the particle, the more likely it is to reach the deeper bronchi or even our respiratory bronchioles, having a greater impact on the human body. Larger particles, due to their size, are less likely to deposit in the deeper bronchi. This is why everyone has been talking about PM2.5 recently — because its diameter is so small that it can even penetrate the walls of the airways and enter the bloodstream, affecting the entire body. Therefore, it has a significant impact on human health.
What harm does haze cause to humans?
Haze has a major impact on human health. A person normally breathes 12 to 16 times per minute, taking over 20,000 breaths per day. Whether we like it or not, we exchange gases with the environment at least tens of thousands of times daily. If the air we breathe is not clean, it can be very harmful to our health. One of the most deadly diseases caused by this is lung cancer. Currently, lung cancer ranks first among both men and women in our country. One of the main reasons for the increase in lung cancer is environmental pollution, which includes PM2.5.
When haze occurs, people often feel very uncomfortable, experiencing coughing, breathing difficulties, throat itching, eye irritation, and a series of other discomforts. The primary sensation is coughing. Coughing first makes people feel very fatigued. Secondly, it can trigger certain symptoms, such as insomnia, muscle soreness, hoarseness, and urinary incontinence in women. Thirdly, it can cause slow, destructive arrhythmias. Fourthly, it can worsen hernias and, in severe cases, lead to pneumothorax, endangering the patient’s life.
In hazy weather, doctors in the respiratory department can clearly notice an increase in the number of patients seeking treatment. Some are elderly, some are children, and others are those who already have underlying respiratory conditions, such as chronic bronchitis or asthma. They mostly come to the respiratory department for treatment. Both children’s hospitals and general hospitals are overcrowded.
Listing two incidents that occurred abroad can help us understand the power of haze. London, once known as the "foggy city" in the UK, experienced the Great Smog of 1952, which claimed 4,000 lives in just four days and caused 12,000 deaths in a short period. Another example is the Donora Smog event in the United States in October 1948, where 6,000 people fell ill and 17 died in a short time.
How can we combat haze?
After hazy weather occurs, various responses have emerged. Government departments have taken 30% of official vehicles off the road; primary school students are advised to stay in classrooms and avoid running on the playground; transportation authorities recommend that people drive as little as possible.
It is important to note that the human lung is like a rather delicate child. For example, the lungs have five lobes, and even if half of the lung function is lost, a person can still live normally without particularly obvious symptoms, perhaps only experiencing coughing or shortness of breath, which are often overlooked and result in lung damage. Therefore, even if you don’t feel any particular discomfort during hazy weather, you should still try to protect your lungs by doing the following:
First, close windows and doors. Avoid outdoor activities.
Second, use air purifiers to reduce fine particulate pollution in the air.
Third, if you need to go out, it is recommended that you wear a mask.
What kind of mask is good for protection against haze?
Cotton mask haze prevention rating: ★
Colorful cartoon-patterned masks are often seen on the streets. These masks primarily serve to keep you warm but do not effectively block bacteria, viruses, or inhalable particulate matter.
Gauze mask haze prevention rating: ★★
The principle behind gauze masks is mechanical blocking, but because the gaps in the gauze are relatively large, they can block particles larger than PM2.5 but offer very weak protection against PM2.5 particles.
Activated carbon mask haze prevention rating: ★★
These contain some activated carbon components, which mainly help block harmful gases in the air but still cannot prevent fine particles.
N95 mask haze prevention rating: ★★★
N95 masks are medical-grade specialized masks that offer good protection against PM2.5. However, wearing them for just six hours will almost certainly cause headaches, similar to oxygen deprivation, because they fit so tightly and can feel very uncomfortable. Therefore, it is not recommended to wear N95 masks outdoors, especially not suitable for the elderly.
Regular medical mask haze prevention rating: ★★★
These masks can block particles as small as PM4, but their blocking rate for particles smaller than 3 micrometers is not high.
Surgical medical mask haze prevention rating: ★★★★★
Surgical medical masks have an additional layer compared to regular medical masks, making them more effective.