On July 26, 1943, Los Angeles was covered by a thick, eye-irritating gas that blocked out the sun. People were worried, thinking it might be a chemical attack. However, it turned out to be smog, not an act of war. Smog, a mix of smoke and fog, was a term first used in the early 1900s to describe the thick gray haze over cities like London. This type of smog, known as industrial smog, was caused by smoke from coal-burning stoves and factories mixing with moisture in the air.
The smog in Los Angeles was different. It had a yellowish color and a chemical smell. Since the city didn’t use much coal, the cause was unclear until chemist Arie Haagen-Smit discovered two main culprits: volatile organic compounds (VOCs) and nitrogen oxides. VOCs are compounds that easily become gases and can include elements like carbon, oxygen, hydrogen, chlorine, and sulfur. Some VOCs are naturally produced by plants and animals, while others come from human-made sources like solvents, paints, glues, and petroleum. Nitrogen oxides, on the other hand, are released during the incomplete burning of gasoline in vehicles, giving the smog its yellowish tint.
VOCs and nitrogen oxides react with sunlight to create secondary pollutants called PANs and ground-level ozone. These pollutants can irritate the eyes and damage lung tissue, making them key components of photochemical smog, which was affecting Los Angeles.
Smog impacts some cities more than others due to a mix of human pollution and local weather conditions. Industrial smog is common in places with high humidity, like London, while photochemical smog is more intense in urban areas with calm winds and warm, sunny weather. Sunlight’s ultraviolet radiation breaks down molecules that contribute to smog. Cities surrounded by mountains, like Los Angeles, or located in basins, like Beijing, are particularly vulnerable because smog has limited space to disperse. Temperature inversion, where a layer of warm air traps pollution near the ground, also plays a role.
Smog is not just an eyesore; it can irritate the eyes, nose, and throat, worsen conditions like asthma and emphysema, and increase the risk of respiratory infections such as bronchitis. It is especially harmful to young children and the elderly, and exposure during pregnancy has been linked to low birth weight and potential birth defects. Photochemical smog can also damage crops, reducing yields and making them more vulnerable to pests.
For many years, smog was seen as an unavoidable part of city life. Londoners got used to the infamous fog until the Great Smog of 1952, which stopped transportation and caused over 4,000 respiratory deaths. This led to the Clean Air Act of 1956, banning coal burning in certain areas and reducing smog levels. Similarly, regulations on vehicle emissions and fuel content in the United States have decreased smog levels.
Despite these efforts, smog remains a significant issue worldwide. Countries like China and Poland, which rely on coal for energy, experience high levels of industrial smog. Rapidly developing cities, including Mexico City, Santiago, New Delhi, and Tehran, are affected by photochemical smog and vehicle emissions. Governments have implemented strategies like restricting car usage to combat smog. As more than half of the global population moves to urban areas, transitioning to mass transit and reducing reliance on fossil fuels may help improve air quality.
Design an infographic that illustrates the formation of smog, highlighting the roles of VOCs, nitrogen oxides, and sunlight. Use visuals to explain the differences between industrial and photochemical smog. This will help you better understand the chemical processes involved and the environmental conditions that exacerbate smog.
Choose a city affected by smog, such as Los Angeles, Beijing, or London. Research the historical and current smog issues in that city, including causes, health impacts, and measures taken to reduce smog. Present your findings to the class, focusing on how local geography and policy have influenced smog levels.
In a controlled lab setting, simulate the formation of smog using safe chemicals that represent VOCs and nitrogen oxides. Observe how these chemicals react under a UV light to form smog-like conditions. Document your observations and discuss how this experiment relates to real-world smog formation.
Participate in a class debate on the effectiveness of government regulations in reducing smog. Consider historical examples like the Clean Air Act and current policies in various countries. Discuss the balance between economic growth and environmental protection, and propose additional measures that could be implemented.
Create a campaign aimed at raising awareness about the health and environmental impacts of smog. Develop posters, social media content, or a short video that educates the public on how they can contribute to reducing smog, such as using public transportation or supporting clean energy initiatives.
On July 26, 1943, Los Angeles was enveloped by a thick gas that irritated people’s eyes and obscured the sun. Alarmed residents feared their city had been attacked with chemical weapons. However, the cloud was not an act of war; it was smog. A combination of smoke and fog, the term “smog” was first used in the early 20th century to describe the dense gray haze that covered cities like London, Glasgow, and Edinburgh. This industrial smog typically formed when smoke from coal-burning stoves and factories mixed with moisture in the air.
The smog in Los Angeles was different; it had a yellowish tint and a chemical smell. Since the city did not rely heavily on coal, its origins remained unclear until chemist Arie Haagen-Smit identified two main contributors: volatile organic compounds (VOCs) and nitrogen oxides. VOCs are compounds that easily vaporize and can include elements such as carbon, oxygen, hydrogen, chlorine, and sulfur. Some VOCs are naturally produced by plants and animals, while others come from human-made sources like solvents, paints, glues, and petroleum. In contrast, nitrogen oxides are released during the incomplete combustion of gasoline in motor vehicles, contributing to the yellowish color of this type of smog.
VOCs and nitrogen oxides react with sunlight to create secondary pollutants known as PANs and ground-level ozone. Both PANs and ozone can cause eye irritation and damage lung tissue, making them key components of photochemical smog, which was affecting Los Angeles.
So, why does smog impact some cities more than others? Both industrial and photochemical smog result from a combination of human pollution and local weather conditions. London’s high humidity made it susceptible to industrial smog, while photochemical smog is most intense in urban areas with calm winds and warm, sunny weather. The ultraviolet radiation from sunlight provides the energy needed to break down molecules that contribute to smog formation. Cities surrounded by mountains, like Los Angeles, or located in basins, like Beijing, are particularly vulnerable to smog because there is limited space for it to disperse. This is also influenced by a phenomenon called temperature inversion, where a layer of warm air traps pollution close to the Earth’s surface.
Smog is not just an unsightly problem; it can irritate the eyes, nose, and throat, worsen conditions like asthma and emphysema, and increase the risk of respiratory infections such as bronchitis. It can be especially harmful to young children and the elderly, and exposure during pregnancy has been linked to low birth weight and potential birth defects. Secondary pollutants found in photochemical smog can also damage crops and reduce yields, making them more vulnerable to pests.
For many years, smog was viewed as an unavoidable consequence of urban life. Residents of London became accustomed to the infamous fog until the Great Smog of 1952, which paralyzed transportation in the city for days and resulted in over 4,000 respiratory deaths. This led to the Clean Air Act of 1956, which prohibited coal burning in certain areas, significantly reducing smog levels. Similarly, regulations on vehicle emissions and fuel content in the United States have decreased the volatile compounds in the air and, consequently, smog levels.
Despite these efforts, smog continues to be a significant issue worldwide. Countries like China and Poland, which rely on coal for energy, experience high levels of industrial smog. Rapidly developing cities, including Mexico City, Santiago, New Delhi, and Tehran, are affected by photochemical smog and airborne particles from vehicle emissions. Governments have implemented various strategies to combat smog, such as restricting car usage for certain periods. As more than half of the global population moves to urban areas, transitioning to mass transit and reducing reliance on fossil fuels may help improve air quality.
Smog – A type of air pollution caused by the interaction of sunlight with pollutants such as vehicle emissions and industrial fumes. – The city issued a smog alert, advising residents to limit outdoor activities due to poor air quality.
Pollution – The introduction of harmful substances or products into the environment, leading to adverse effects on ecosystems and human health. – Efforts to reduce pollution have led to stricter regulations on industrial waste disposal.
Compounds – Substances formed when two or more chemical elements are chemically bonded together, often contributing to environmental changes. – Nitrogen oxides and sulfur dioxide are compounds that contribute to acid rain.
Ozone – A molecule composed of three oxygen atoms, found in the Earth’s stratosphere, that absorbs most of the sun’s ultraviolet radiation. – The depletion of the ozone layer has raised concerns about increased UV exposure and its effects on skin cancer rates.
Emissions – The release of gases or particles into the atmosphere, often from industrial processes or vehicles, contributing to air pollution. – Reducing carbon emissions is crucial for mitigating climate change impacts.
Respiratory – Relating to or affecting the organs involved in breathing, often impacted by air quality and pollutants. – Prolonged exposure to polluted air can lead to serious respiratory issues, such as asthma and bronchitis.
Temperature – A measure of the warmth or coldness of an environment, which can influence weather patterns and climate conditions. – Rising global temperatures are a significant indicator of climate change.
Humidity – The amount of water vapor present in the air, affecting weather conditions and human comfort levels. – High humidity levels can exacerbate the effects of heat, making it feel hotter than it actually is.
Sunlight – The natural light emitted by the sun, essential for photosynthesis and influencing climate and weather patterns. – Sunlight is a critical factor in the process of photosynthesis, enabling plants to produce oxygen and energy.
Health – The state of physical and mental well-being, often influenced by environmental factors such as air and water quality. – Access to clean air and water is fundamental to maintaining good health and preventing disease.
