7. What is smog?

Smog is a type of air pollution characterized by a mixture of smoke and fog, hence the term "smog," which is a portmanteau of "smoke" and "fog." Smog occurs when pollutants such as nitrogen oxides (NOx), volatile organic compounds (VOCs), particulate matter (PM), and ground-level ozone (O3) combine with atmospheric moisture, sunlight, and temperature inversions to form a thick haze or fog-like layer in the lower atmosphere. Smog can occur in both urban and rural areas and is often associated with industrialization, vehicular emissions, and atmospheric conditions conducive to pollutant accumulation. There are two primary types of smog: Sulfurous (or "London") Smog: Sulfurous smog, historically known as "London smog," is characterized by high concentrations of sulfur dioxide (SO2) and particulate matter, primarily from the burning of coal and other fossil fuels in industrial processes, power plants, and residential heating systems. Sulfurous smog is typically grayish-yellow in color and has a distinct odor of sulfur dioxide. It can cause respiratory problems, eye irritation, and exacerbate health conditions such as asthma and bronchitis. Photochemical Smog: Photochemical smog, also known as "Los Angeles-type smog" or "summer smog," is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) from vehicle emissions, industrial activities, and other sources react with sunlight in the presence of atmospheric oxygen and heat to produce ground-level ozone (O3) and secondary pollutants such as peroxyacetyl nitrate (PAN) and other oxidants. Photochemical smog is characterized by a brownish-yellow haze and is often more prevalent in warmer months and urban areas with high levels of traffic and industrial activity. It can irritate the eyes, throat, and respiratory system, exacerbate respiratory conditions, and contribute to the formation of respiratory illnesses. Both types of smog can have adverse effects on human health, the environment, and ecosystems. Long-term exposure to smog pollutants can lead to respiratory diseases, cardiovascular problems, impaired lung function, and premature mortality. Smog can also damage crops, vegetation, and ecosystems, reduce visibility, and contribute to climate change by altering atmospheric composition and heat absorption. Efforts to reduce smog pollution involve implementing air quality regulations, improving emissions controls on vehicles and industrial sources, promoting cleaner energy sources and technologies, increasing public awareness, and adopting sustainable urban planning and transportation strategies to mitigate air pollution and protect public health and the environment. read less