With the help of famous events in the history of foggy days

In the past week, a rare large-scale haze has shrouded China. More than a hundred large and medium-sized cities in 25 provinces have experienced haze weather to varying degrees, covering nearly half of China’s land. . South Korea's "Central Daily News" reported that the gray disaster "China's haze" caused by China has reached the "worst level in history." The suffocating haze stays over Beijing like a ghost, and Beijing's air pollution index is higher than The standard value set by the World Health Organization is 16.8 times so high that even if you wear a thick dust mask outdoors, "you can still smell the pungent smell" and "Beijing has become a city where you can't open your mouth to speak." . The U.S. Embassy in China even called it "poison gas" and advised its citizens to "not go out." Fog is a natural weather phenomenon and is not necessarily related to man-made pollution; haze is caused by particulate matter pollution. The main difference between the two is the air humidity. When the humidity is greater than 90%, it is usually called fog, while when the humidity is less than 80%, it is called fog. It is called haze, and when the humidity is between 80% and 90%, it is haze. Later, some people used the word smog to specifically refer to the mixture of particulate matter and smog caused by industrial emissions. Historically, many countries have experienced air pollution incidents caused by particulate matter.

An inventory of famous smog events in history

The Maas Valley haze incident in Belgium in 1930: The Maas Valley is a 24-kilometer-long river valley next to the Maas River in Belgium. . The Maas Valley area is an important industrial area, with 3 oil refineries, 3 metal smelters, 4 glass factories and 3 zinc smelting plants, as well as electricity, sulfuric acid, fertilizer plants and lime kilns. The industrial area All in a narrow basin. From December 1 to 15, 1930, the entire Belgium was covered in heavy fog and the climate was abnormal. Due to its special geographical location, a strong temperature inversion layer appears over the Maas Valley. Generally, the higher the airflow rises, the cooler the air temperature is. But when the climate is abnormal, the air temperature in the lower layers will be lower than the air temperature in the upper layers, causing a "temperature reversal" phenomenon. This reversal of the atmosphere is called a "reversal layer." The reversal layer will inhibit the rise of smoke, causing the smoke and dust in the atmosphere to accumulate. It accumulates under the reversal layer and cannot be convectively exchanged, causing air pollution. Under the influence of this temperature inversion layer and heavy fog, large amounts of smoke emitted by 13 factories in the Maas Valley Industrial Zone filled the sky above the valley and could not spread. Harmful gases accumulated thicker and thicker in the atmosphere, and their accumulated amounts were close to the limit of harming health. . Starting from the third day, due to the combined effects of sulfur dioxide and several other harmful gases and dust pollution, thousands of people in the River Valley Industrial Zone developed respiratory diseases. Symptoms include: chest pain, coughing, tearing, sore throat, hoarseness, and nausea. , vomiting, difficulty breathing. More than 60 people died in one week, which was more than ten times the normal number of deaths during the same period. Among them, patients with heart disease and lung disease have the highest mortality rate. Many domestic animals did not survive the disaster and died one after another.

An inventory of famous smog incidents in history

Photochemical smog incident in Los Angeles, USA in the 1940s: Los Angeles, on the southwest coast of the United States, faces the sea to the west and is surrounded by mountains on three sides. The early development of gold mines, oil and canals, coupled with its unique geographical location, soon made it a port city with developed commerce and tourism. However, the good times did not last long. Since the early 1940s, people have discovered that this city has changed from its previous gentleness and become "crazy". Every year from summer to early autumn, as long as it is a clear day, a light blue smog that fills the sky will appear over the city, making the sky above the entire city turbid. This kind of smoke can cause red eyes, sore throat, stuffy breathing, dizziness and headache. After 1943, the smog became more raging, causing large pine forests on the 2,000-meter-high mountain one kilometer away from the city to die, and citrus production decreased. This is the famous Los Angeles photochemical smog pollution incident. Photochemical smog is caused by automobile exhaust and industrial waste gas emissions. It generally occurs at noon or afternoon on sunny days in summer when the humidity is low and the temperature is between 24°C and 32°C. After the hydrocarbons and nitrogen dioxide in automobile exhaust are discharged into the atmosphere, they undergo photochemical reactions under strong sunlight and ultraviolet rays, and the products are highly toxic photochemical smog. In the 1940s, Los Angeles consumed approximately 1,100 tons of gasoline per day and emitted more than 1,000 tons of hydrocarbons, more than 300 tons of nitrogen oxides, and more than 700 tons of carbon monoxide. In addition, other oil combustion emissions from refineries, fuel supply stations, etc., these compounds are emitted into the sky above sunny Los Angeles, creating a toxic smog factory. The picture shows Los Angeles in heavy fog.

An inventory of famous smog incidents in history

The 1948 Donora smog incident in the United States: Donora is a small town in Pennsylvania, located 30 kilometers south of Pittsburgh. The town is located inside a horseshoe-shaped river bend, with hills on both sides sandwiching the town into the valley. The town of Donora is home to sulfuric acid plants, steel plants, and zinc smelting plants. For many years, the chimneys of these plants have been spewing smoke and mist into the air, and the residents of the town are accustomed to the strange smell in the air. From October 26 to 31, 1948, a persistent fog made the town of Donora look particularly dark. The climate is humid and cold, the sky is overcast, and there is no wind. The air loses its vertical movement up and down, causing a temperature inversion.

In this dead wind state, the factory chimneys did not stop emitting smoke, as if they were about to break through the frozen atmosphere. Two days have passed, and the weather has not changed, except that the smoke in the atmosphere is getting thicker and thicker, and a large amount of smoke emitted by the factory is enclosed in the valley. The pungent smell of sulfur dioxide in the air was nauseating. Visibility was so low that the factory, except for its chimneys, was lost in smoke. What followed was a sudden onset of illness among 6,000 people in the town, with symptoms including eye disease, sore throat, runny nose, cough, headache, chest tightness, vomiting, etc., and 20 of them died soon after. Most of the deceased were over 65 years old, and most of them had heart disease or respiratory diseases. The main reason for the smog incident was that gases and metal particles containing toxic and harmful substances such as sulfur dioxide emitted by factories in the town accumulated in the valley under abnormal climate conditions and persisted. These toxic substances adhered to suspended particulate matter. on, seriously polluting the atmosphere. People inhale a large amount of these toxic gases in a short period of time, causing various symptoms and even serious illness. The Donora smog incident, like the Maas Valley smog incident in Belgium in December 1930 and the Poza Rica incident in Mexico in 1959, are all air pollution incidents caused by industrial smoke emissions.

An inventory of famous smog incidents in history

The 1952 smog incident in London, England: From December 5 to 8, 1952, a disaster struck London, England. There is a high pressure center over the city of London, located in the Thames River Valley. There has been no wind for several days, and the anemometer reads zero. Heavy fog has shrouded the city of London. It is also the time when a large amount of coal is burned in the city in winter. The soot and dust emitted accumulate in the windless state. Smoke and moisture accumulate in the atmosphere, causing the sky above the city to be filled with smoke for four or five consecutive days, with extremely poor visibility. Low. Under such weather conditions, planes were forced to cancel flights, cars had to turn on their lights even when driving during the day, and pedestrians found it extremely difficult to walk and had to fumble along the sidewalk. As pollutants in the atmosphere continue to accumulate and cannot diffuse, many people feel difficulty breathing, stinging eyes, and tears. London hospitals were overflowing due to a sharp increase in patients with respiratory diseases, and coughs could be heard everywhere in London. In just four days, more than 4,000 people died. Two months later, more than 8,000 people died. Even the 350 cows in a grand prize-winning cattle exhibition at that time suffered a tragedy. One cow died on the spot, 52 were seriously poisoned, and 14 of them were dying. This is the appalling "London Smog Incident". The main cause of the London smog incident is the continuous accumulation and fermentation of smoke emitted by coal-burning and industrial heating in winter under the inversion layer. Sadly, 10 years later, a similar smog event occurred in London, causing 1,200 abnormal deaths. It was not until the 1970s that London switched to gas and electricity and moved thermal power stations out of the city, reducing urban air pollution by 80%.