An advertisement on the radio warning the public against the dangers of smoking is called a

An advertisement on the radio warning the public against the dangers of smoking is called a "Public service announcement".

Explanation:

A PSA stands for public services announcement. It refers a public interest video circulation without any charges, also in the aim of inducing awareness about social issue and varying public attitudes, behaviours towards it. In the UK named as 'public information’s films' (PIFs) while in Hong Kong termed as 'announcements in the public’s interest' (APIs).

The first public services announcements as moving images form) were made in both the US and the UK before and during the years of World War II. Health and safety are the most popular topics of PSAs, such as digital emergency preparedness & safety tips on air and online campaign.

because health skills are tools and strategies and also practical skills are also something you need to learn (like tools and strategies) and put it in reality.