I'm thinking of getting my downstairs neighbour evicted for smoking pot in a non-smoking apartment
Why does this make you want to have him evicted?
I cannot concentrate and it's causing me headache
If someone is smoking in a non-smoking apartment then they should stop. It's not cool to inconvenience others just because they want to get high.
Exactly. They are being really inconsiderate since I can smell it everyday.
Talk to the landlord and see what can be done. If they don't stop then they should get evicted.