Okay kiddo, let me tell you a story about the Great Smog of London!
Once upon a time, in the year 1952, there was a big problem in the city of London. You know how sometimes on a foggy day, everything looks kind of blurry and gray? Well, imagine that times 100!
The air in London was so polluted and dirty that people could hardly see a few feet in front of them. They had to use torches and even had car accidents because they couldn't see where they were going.
But it wasn't just a problem for vision - it was also really bad for people's health. The air pollution came from factories and homes burning coal, which released smoke and chemicals into the air. It made people's lungs hurt and caused them to cough and have trouble breathing. Animals and plants suffered too, and some even died from the pollution.
The smog was so bad that people started calling it the "Great Smog." It lasted for about five days, and it's estimated that thousands of people died because of it.
After the Great Smog, the government of London realized they needed to take action to clean up the air. They made laws to limit the amount of pollution factories and homes could produce, and worked to make public transportation cleaner.
So, even though the Great Smog was a really bad thing that happened, it also helped people realize that they needed to take better care of the environment and work to prevent things like this from happening again.