Attention! Clear skies do not equal good air quality

As the saying goes, "Don't go out during the 39th and 49th days of winter." January is the time of the year when the average temperature is the lowest. Low temperatures are not only conducive to the spread of viruses, but also a season when smog is more common.

Yellow alert!

Many friends may be wondering, why is there a yellow alert for air pollution when the sky is clear recently? Let's take a look!

"Smog only occurs on cloudy days" seems to be a common perception among the general public. Everyone thinks that a sunny day means the air quality is particularly good, but this is not the case.

What is smog?

"Fog" is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground. It is a weather phenomenon that makes horizontal visibility less than 1 km. Fog is a "liquid".

"Haze" is a phenomenon in which a large number of extremely fine dry dust particles float evenly in the air, making the horizontal visibility less than 5 kilometers or below. Haze is a "solid" air turbidity.

"Smog" is a general term for fog and haze. Generally speaking, when visibility is between 1 and 10 kilometers, there may be both solid matter (the contribution of haze) and liquid matter (the contribution of mist) , which are difficult to distinguish, so it is called the "smog" phenomenon.

“Haze” is a carrier of many harmful substances

PM2.5 particles are the main component of haze and are the "culprit" that causes smog weather. Due to their small particle size and large specific surface area, they can carry a lot of heavy metal ions (such as lead, pot, arsenic, etc.), chemical substances (such as sulfate, formaldehyde, etc.) and bacteria, viruses and other toxic and harmful substances, which cause the greatest harm to the human body.

1. Water-soluble ions: They are the main components of PM2.5 and directly affect the pH of atmospheric precipitation. They mainly include fluoride, chloride, sulfate, nitrate and ammonium salt, etc. They come from the secondary transformation process of smoke produced by coal combustion in the air; they are also secondary transformation products of motor vehicle exhaust emissions.

2. Metal and metalloid elements: PM2.5 easily absorbs toxic metals and metalloids in the air, including antimony, aluminum, arsenic, beryllium, cadmium, chromium, mercury, lead, manganese, thallium, selenium, etc. They come from industrial sources such as steel, cement, coal-fired boilers, mobile sources such as motor vehicles, and restaurant fumes, decoration and other emissions.

3. Polycyclic aromatic hydrocarbons: a type of persistent organic pollutant. They mainly include: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, etc. They come from the industrial production of coal and crude oil, incomplete combustion of organic matter during heating, fire, garbage incineration, vehicle traffic, smoking and volcanic activities.

Generally speaking, the smog in cities mainly comes from industrial pollution, domestic pollution and traffic pollution, and these pollutions will not stop whether it is sunny or rainy, and what should exist in the air will eventually exist in the air. It cannot be said that it does not exist just because it cannot be seen by the naked eye.

Haze can cause damage to multiple systems

The elderly, children, and people with underlying diseases are more vulnerable to the attack due to their lower immunity and should be paid more attention to .

PM2.5 particles are small in size and easily deposited in the alveolar area. Atmospheric particles that enter the respiratory tract will destroy the defense function of the respiratory tract, damage lung function, cause coughing, sputum, chronic bronchitis, emphysema and other diseases, induce or aggravate inflammation, and cause the occurrence of asthma in children and adults and worsen symptoms.

PM2.5 can stimulate the vagus nerve in the lungs, causing autonomic nervous system disorders and affecting the heart, causing cardiac toxicity such as changes in heart rate variability, myocardial ischemia, myocardial infarction, arrhythmia, atherosclerosis, etc.

PM2.5 can cause toxicity to the blood system . It can cause coagulation abnormalities and increase blood viscosity in the body, thereby leading to cardiovascular events such as atherosclerosis and myocardial infarction. It is a potential hidden danger for vascular accidents.

PM2.5 contains a lot of heavy metals and polycyclic aromatic hydrocarbons, which can damage genetic material, interfere with normal cell division, destroy the body's immune function , and cause cancer and deformity. It can easily lead to intrauterine growth retardation and low birth weight. Toxins can also pass through the placenta and directly poison the fetus, especially in early pregnancy.

Scientific research data shows that the hazards of PM2.5 to human health are complex and diverse, and some of the harmful effects have not yet been fully understood by humans.

Personal protection measures during haze

1. It is recommended that susceptible groups such as children, the elderly, and patients with respiratory, cardiovascular and cerebrovascular diseases reduce outdoor activities , and encourage them to take public transportation as much as possible and reduce the number of motor vehicles on the road.

2. During outdoor activities, protective measures such as wearing masks can be adopted .

3. Maintain personal hygiene . When entering indoors from outdoors, you should wash your face, rinse your mouth, and clean your nose in time to remove any contaminants on your body.

4. Eat a light diet and drink plenty of water . It is advisable to choose light, easy-to-digest and vitamin-rich foods. Drink plenty of water, eat more fresh vegetables and fruits, and supplement various vitamins and inorganic salts to moisten the lungs and remove dryness, remove phlegm and relieve cough, and strengthen the spleen and kidney. Eat less irritating foods and eat more pears, loquats, oranges, tangerines and other foods that clear the lungs and reduce phlegm.

5. There is less sunshine in winter, and insufficient ultraviolet radiation can cause insufficient production of vitamin D in the human body. Some people will experience mental laziness, depression, etc., so they can supplement vitamin D appropriately .

6. Try to smoke less or quit smoking . Cigarettes, cigars and pipes produce harmful fine particles when burned. Tobacco smoke contains more than 7,000 compounds, which can seriously harm the health of smokers and people who inhale "second-hand smoke". In smog weather, it is like "adding insult to injury".

How to open windows for ventilation during haze?

Studies have found that when doors and windows are closed and there is no indoor pollution caused by smoking, fuel burning, cooking fumes and other human activities, the indoor PM2.5 concentration is generally 70% to 85% of the outdoor concentration. These particles mainly penetrate from the outdoor into the indoor through gaps such as doors and windows. For example, when the outdoor PM2.5 concentration is 500μg/m3, the indoor concentration is 350μg/m3 to 425μg/m3. Therefore, on foggy days when outdoor PM2.5 pollution is heavy, doors and windows should be closed and air purifiers should be used, but when using air purifiers, proper ventilation should also be taken into account.

If you really need to open windows for ventilation during smog weather, you should try to avoid the peak hours of smog in the morning and evening. You can open the windows a little for ventilation for half an hour to an hour each time . You can also plant more green plants on the balcony, terrace, and indoors, such as green crown leaf plants such as green radish, evergreen, and tiger skin plant, because their leaves are larger and have relatively strong adsorption capacity.