Uses of fuels in cars , industries , household activities , etc.
77% i think
The answer is smog
Humans)
Urbanization and industrialization
Major cities are large urban or metropolitan areas in a state, country, or region. Major cities of the world include Beijing, Hong Kong, London, Paris, and New York City.
Subways are located in most major metropolitan cities such as New York, Miami, Los Angeles, and Philadephia.
Madrid, Barcelona, and Valencia are three of the major Spanish cities with vibrant cultures, historical landmarks, and bustling metropolitan areas.
fossil fuels
automobiles
All major metropolitan cities do have a Chamber of Commerce. Smaller cities usually do not have a Chamber of Commerce. This is an organization that attempts to attract businesses to a city.
Oil spills is the biggest cause of marine pollution. An oil spill can devastate and area of the ocean. Factories are another major cause of marine pollution.
"Many major United States metropolitan cities are considered to be cities of the future. Some of these cities are Los Angeles, New York City, Chicago, and Washington D. C."