Across many major cities, a hazy brown soup of pollution hangs over the skyline, especially in the warmer months. This is smog, known more specifically as ground-level ozone. Smog is air pollution that reduces visibility. Smog is formed when industrial emissions from power plants, factories, cars, and other sources react with heat and sunlight in the atmosphere.
Smog is unhealthy to humans and animals, and it can kill plants. It can irritate your eyes, nose and throat. Also, it can worsen existing heart and lung problems or perhaps cause lung cancer with regular long-term exposure. It also results in early death.