Fossil fuels are non-renewable sources of energy as they are derived from pre-historic fossils and it is certain that they will deplete in the near future.
The bigegst disadvantage of the fossil fuels is that they release carbon dioxide, nitrogen dioxide, sulfur dioxide, carbon monoxide gasses, which lead to serious environmental issues such as air pollution. They are responsible for the global warming..
Besides the environmental effect, carbon dioxide can also cause serious health complications such as chronic asthma, low lung functioning, chronic bronchitis..