Scientific history
▲"Faced the crisis - Social Development and Environmental Protection" Cover
Collection of the mystery of smoke
▲Sunshine and smoke
During World War II, Los Angeles, USA suffered a serious attack. The invaders were not the Japanese who had sneaked into Pearl Harbor, but the smoke scattered in the air. According to the Los Angeles Times, on July 26, 1943, a huge smoke screen fell to the city, causing a sharp drop in visibility in the city center, making buildings and streets hazy. During this sun-blocked day, thousands of residents in Los Angeles felt their eyes sting and their throats were scratched, accompanied by symptoms such as coughing, tears, and sneezing. In severe cases, they were uncomfortable in breathing, dizziness, nausea, and extremely uncomfortable. They realized that there were serious problems in the city where they lived.
Los Angeles is located on the west coast of the United States, backed by the coastal mountains and facing the Pacific Ocean. It has a bright sunshine, a warm climate and a beautiful scenery. Due to the early development of gold mines, canals, etc., Los Angeles' economic development level is very rapid. The development of oil in 1936, especially after the outbreak of World War II, led by aircraft manufacturing and military industry, the city gradually became an important seaport in the western United States and the third largest city in the United States, with its population and motor vehicle scale growing rapidly. However, urban prosperity has also brought about air pollution problems. According to the meteorological department records, visibility in Los Angeles dropped rapidly from 1939 to 1943, and people could only see up to three blocks during the day mentioned above. Rumors even pointed out that Los Angeles' Monroville Airport was once considering relocation to stay away from this constant smog weather.
Los Angeles residents are increasingly worried about the smoke that is dense in front of them and is gradually affecting the government. In October 1943, the Los Angeles County Council appointed a smoke exhaust committee to study the issue. According to the committee's recommendation, the county council proposed in 1945 to ban thick smoke emissions and establish an air pollution control agency. Soon, the city of Los Angeles adopted similar smoke exhaust management measures, but other cities in Los Angeles County did not take action.
At first, Los Angeles people in the smoke believed that factories were the culprit for the emission of smoke, but as the investigation progressed, people's perceptions changed new. In August 1945, Los Angeles County health official Svottot published a series of articles in the Pasadena Star, believing that smoke originated from multiple places, such as diesel trucks, home backyard incinerator , urban garbage dumps, etc. He even accurately pointed out the natural factors that bring smoke, that is, Los Angeles is in a basin, with the main air current below the atmospheric state. Coupled with the influence of the inverter layer, it is very unfavorable to the diffusion of pollutants and is very likely to form smoke. 1 Air pollution expert Raymond Tucker also holds the same view. In an article published in the Los Angeles Times in 1946, he pointed out: "Be careful when citing the problem entirely on industry or factories, because everyone will do what causes pollution." 2 Tucker put forward 23 detailed opinions, including prohibiting the incineration of garbage in home backyard incinerators and garbage dumps, and prohibiting the use of smoked trucks. In addition, he also suggested establishing a strong county-wide air pollution management agency to take timely pollution control measures.
Tuck's proposal was realized in 1947. On April 15 of that year, the Los Angeles County Council approved the draft legislation to establish a unified air pollution control area in the county. In response, the California City Alliance expressed support, believing that county-wide air pollution control is more effective than individual cities. The bill was passed by both the California Senate and House of Representatives and was signed and entered into force on June 10 by Gov. Earl Warren. Four months later, the Los Angeles County Air Pollution Control District was established as the first relevant agency in the United States. On December 30, the control zone enforced the air quality plan, requiring all major companies to have air pollution permits. In the following 10 years, Orange County , Riverside County and San Bernardino County established their respective control areas and merged later.
Although a county-wide unified air pollution control area has been established, people still do not know the specific components and causes of smoke, nor how to control it.
In 1948, farmers near oil refineries in southern California complained that air pollution affected their crops and allowed plant leaves to bleach, which was not the case in other regions. Based on this clue, J. Hagen Smit, a professor of chemistry at Caltech, began studying plants damaged by smoke. Hagen Smit noted that despite the smoking control measures, residents could smell a strange bleach on smoke days. At the same time, a colleague told him that he had tears in his eyes while driving, so he could no longer open his eyes to drive. So, after comprehensive consideration, he began to pay attention to the highly oxidized elements in the air in Los Angeles. In 1950, through experiments, Hagen Smit finally locked his eyes on ozone , which can cause eye sting and damage the respiratory tract.
But, where does ozone come from? In order to clarify the problem, Hagen Smit went to the refinery to collect some air samples and concluded through experiments that under the sunlight, the hydrocarbon from the refinery had a photochemical reaction with the nitrogen oxide emitted from the incomplete combustion of the automobile gasoline, forming ozone. In fact, in addition to ozone, photochemical smoke also includes nitrogen oxides, acetaldehyde and other oxidants, which are what they cause harm to human health.
took action to control smoke
grasped the causes of photochemical smoke, and the Los Angeles government also took action immediately. They focused their attention on oil fields, refineries, etc. that emit hydrocarbons, and other oil industries throughout the local oil industry. Due to the extremely strict measures taken, hydrocarbons have been emitted from 2,100 tons per day in 1947 to 250 tons per day in 1957. It can be said that such achievements are quite gratifying. At the same time, the local government has properly handled the open-air incineration problem of garbage dumps, reduced factory flue gas emissions, banned incinerators in the backyard of homes that emit black smoke, and adjusted the heating problem of Southern California orchards. 3
However, even so, photochemical smoke still exists in large quantities, and it is even becoming increasingly fierce. The above-mentioned photochemical smoke incident in Los Angeles in 1943 caused more than 400 deaths, which is only the number of deaths of elderly people over 65 in the same incident in December 1952. In September 1955, photochemical smoke caused more than 400 elderly people to die in just two days, and more people suffered from symptoms such as eye sting and difficulty breathing due to smoke stimulation. Some scholars have counted the number of days reported by Los Angeles County for residents to suffer from eye allergies, of which 187 days were reported in 1959, 198 days in 1960, 186 days in 1961, and 212 days in 1962. 4 Such data shows that the air pollution in Los Angeles County has not improved, but has continued to worsen.
really changed in 1953. The first winter of the winter, the murderous smoke in London claimed 4,000 lives. Fearing that the same disaster would come to Los Angeles, Gov. Goodwin Knight appointed chemist Arnold Beckman to form a committee to investigate and propose air pollution control. After more than a year of hard work, the Beckman-led committee has put forward several far-reaching recommendations planned to be implemented by the government air management agency in the coming years. They proposed:
1 to reduce oil refineries, reduce evaporation leakage during refueling, and further reduce hydrocarbon emissions.
2 Establish automobile exhaust emission standards.
3 Diesel trucks and buses use propane as fuel to replace the previous diesel.
4 The heavy pollution industry is considering slowing down its development speed.
5 Outdoor garbage is prohibited.
6 Develop a rapid transportation system. 5
1 Reduce refineries, reduce evaporation and leakage during refueling, and further reduce hydrocarbon emissions.
2 Establish automobile exhaust emission standards.
3 Diesel trucks and buses use propane as fuel to replace the previous diesel.
4 The heavy pollution industry is considering slowing down its development speed.
5 Outdoor garbage is prohibited.
6 Develop a rapid transportation system. 5
▲Los Angeles
In these suggestions, the committee has noticed the emissions of automobile exhausts.In fact, while the oil industry emits 500 tons of hydrocarbons per day, the automobile emissions are 1,300 tons - this is the biggest "culprit" of the photochemical smoke in Los Angeles. However, in a country like the United States on a wheel, automobiles not only drive the development of manufacturing, but also create rich economic and cultural benefits. In the process of Los Angeles becoming more urbanized, cars have played an irreplaceable role. In the early 1940s, Los Angeles owned 2.5 million cars, consumed 1,100 tons of oil every day, discharged more than 1,000 tons of hydrocarbons, more than 300 tons of nitrogen oxides, and more than 700 tons of carbon monoxide. 6 The concentration of the irritating photochemical smoke formed by so much exhaust gas can be imagined once it is shined by the local bright and warm sunlight. Therefore, the challenges facing the management of automobile problems here are huge.
Los Angeles people did not retreat. At the institutional level, recognizing that a county cannot effectively control the pollution of motor vehicles, the California Legislature founded the California Motor Vehicle Pollution Control Bureau, giving it the power to "test vehicle exhaust emissions and approve emission control devices"7. At the same time, some officials argued for their own and the people's health. Among them, Los Angeles County Inspector Kenneth Hahn forced Detroit auto tycoons to produce and install exhaust pollution control devices through his own efforts. In February 1953, Hahn wrote to Ford's general manager, asking whether his company was conducting research on eliminating or reducing exhaust emissions, but got answers to the research plan that none of the automakers did. Hahn perseveres and constantly urges auto manufacturers to develop exhaust control devices. By the end of 1953, automakers said they had started research on the device, and after repeated questioning by Hahn, they responded in 1955 that they would develop such a device to reduce hydrocarbons in exhaust gases. 18 months later, Hahn asked again whether the device was installed on a car produced in 1957, and the answer was that it was possible the following year. Communications continued, and by November 18, 1960, General Motors told Hahn that a crankcase purifier would be installed on a car produced in 1961 for California, but it did not work well. It was not until 1966 that the improved exhaust control device was officially installed on new cars in California.
Due to the installation of exhaust gas control devices, from 1966 to 1968, the daily hydrocarbon emissions of Los Angeles motor vehicles decreased by 200 tons, and the emissions of carbon monoxide and carbon dioxide also decreased a lot. However, while these harmful substances are reduced, another toxic substance, , nitrogen peroxide, , is showing an increase. To solve this problem, California first issued mandatory regulations in 1975 requiring automobiles to install catalytic converters to reduce emissions of hydrocarbons, carbides and nitrogen oxides that produce nitrogen peroxide. As someone said: "The air quality in Los Angeles has been improved due to this government mandatory measure." 8
▲Los Angeles in the smoke
At the same time, Los Angeles and its California are also taking other methods to limit car exhaust. Since 1970, Los Angeles has firmly implemented the Clean Air Act passed by the U.S. government, gradually phased out the use of leaded gasoline, and advocated the use of methanol and natural gas instead of gasoline in the 1970s and 1980s to cut half of the motor vehicle smoke.
It is worth noting that although the Los Angeles government has been constantly trying to control air pollution since 1943, it has only achieved the effect of reducing smoke and has not completely removed the label of "Smoke City" in the United States, because automobile consumption throughout the United States, including Los Angeles, has become a unique culture. It was not until 2007 that after years of hard work, the hat of shame that had been slapped for 60 years was truly taken off. At this time, Los Angeles finally met the standard of clean air.
As two classic cases in the history of air pollution in Europe and the United States, the London smoke in 1952 has different characteristics from the Los Angeles smoke in the mid-20th century. In 1952, London smoke was a typical environmental disaster caused by coal-fired waste gas and weather factors, and it was a coal-fueled air pollution. The history of such disasters dates back to the first half of the 19th century and are air pollution caused by traditional coal-based industries.In contrast, Los Angeles smoke occurred in the 20th century when oil resources were developed and utilized on a large scale. It is a relatively new form of air pollution and has become a development hazard for large cities with developed industries and numerous automobiles. From the perspective of the formation climate, the air is not circulated when both burst, but the former is mostly cold and humid, while photochemical smoke requires warm sunlight in summer. Despite the above differences, both air pollution brought huge casualties and huge property losses, causing serious trauma to people of that era. Fortunately, no matter how terrible the disasters they face or how heavy the price they pay, the locals never choose to give up. For themselves and for the healthy life of their descendants, they struggle unremittingly, even if every effort is only exchanged for small progress. This is where hope lies.
▲ "Facing the Crisis - Social Development and Environmental Protection"
(This article is excerpted from "Facing the Crisis - Social Development and Environmental Protection", China Science and Technology Press, 2014.1.)
