- A lung is a kind of internal organ
- Internal organs are a part of the body
- Hence, lungs are a part of the body

- Lungs are a part of the body
- If something harms something else, then that something also harms the parts of that something else
- Therefore, if something harms the body, then that something also harms the lungs

- If something harms the body, then that something also harms the lungs
- Smoking harms the body
- Therefore, smoking harms the lungs

- Smoking harms the lungs
- Smoking is a kind of method for inhaling smoke
- Hence, inhaling smoke by smoking harms the lungs

- Harming something has a negative impact on / effect on that something
- Damage has a negative impact on a thing
- So, damage can mean harm

- Inhaling smoke by smoking harms the lungs
- Damage can mean harm
- So, inhaling smoke by smoking causes damage to the lungs

- A lung is a kind of organ for breathing air
- When a lung breathes in air the air goes directly to the lungs
- So, a lung is a kind of organ for directly breathing in air

- A lung is a kind of organ for directly breathing in air
- Air contains gasses
- Hence, a lung is a kind of organ for directly breathing in gasses

- A lung is a kind of organ for directly breathing in gasses
- Smoke is a kind of gas
- So, lungs can be used for directly breathing in smoke

- Lungs can be used for directly breathing in smoke
- To inhale means to breathe in
- Hence, lungs can be used for directly inhaling smoke

- Lungs are a part of the body0
- Inhaling smoke by smoking causes damage to the lungs
- Therefore, smoking causes direct damage to the lungs

So, smoking causes direct damage to the lungs
Smoking harms the body in many ways. It is most harmful to which organ?
- Smoking is a kind of method for inhaling smoke 
- Harming something has a negative impact on / effect on that something 
- A lung is a kind of internal organ 
- If something harms something else, then that something also harms the parts of that something else 
- To inhale means to breathe in 
- Smoke is a kind of gas 
- Internal organs are a part of the body 
- Damage has a negative impact on a thing 
- When a lung breathes in air the air goes directly to the lungs 
- Smoking harms the body 
- Air contains gasses 
- A lung is a kind of organ for breathing air