There was no clear medical evidence for harmfulness of smoking before 1970's, so smoking was allowed in any airlines.

USA is one of the earliest state to understand smoking is harmful for others' health, so US FAA banned smoking on all US domestic flights since 1979. But smoking is still allowed on most international flights.

Air Canada is the 1st airline to run system-wide non-smoking policy, since 1987. Most airlines of developed countries followed.

Even China, a rather poor and backward socialist country, banned smoking in all flights since 2000.

Strangely, smoking is still allowed in Olympic Airways of Greece, as well as numerous Middle East airlines like Emirates and Gulf Air, even these countries are richer and more advanced than China!