Smog usually occurs over cities which

Smog usually occurs over cities which burn a lot of fossil fuels. When fossil fuels such as coal, oil, and natural gas are burned, they release pollutants into the air. These pollutants include particulate matter, nitrogen oxides, sulfur dioxide, and volatile organic compounds. When these pollutants react with sunlight, they form a mixture of air pollutants known as smog. Cities with high levels of traffic and industrial activity tend to produce more smog than areas with fewer sources of pollution. Smog can cause a variety of health problems, such as respiratory issues, eye irritation, and cardiovascular problems, so it is important to monitor and manage smog levels in cities.