The worse the air quality, the thicker the clouds?

That's not necessarily true. The poor air quality in cities is not caused by thick clouds. This is mainly due to heavy industry and many vehicles. Waste gas and smoke float in the air and are not easy to disperse. It belongs to industrial smoke and waste gas, which is harmful to human body. Clouds are sometimes thick in mountainous areas, which is a meteorological feature of rainy days. No matter how thick the clouds are, they are harmless to the human body.