Thier hygiene and personal
The answer is Black lung disease
Drugs that break down a psychological barrier against doing other drugs are known as gateways drugs.
A very known gateway drug (or at least one that has been considered as such) is marijuana or weed. A drug that is being widely consumed in various countries and is also being sold as a legal drug in some countries.
The heart rate is different while dancing, studying and riding a bike because the amount of blood needed for each activity is different. Blood pumps as fast as it as needed by the cells, which is why riding a bike has fast heart rate while studying has a regular heart rate.
