It is known that smoking is harmful to our ______ (healthy).

It is known that smoking is harmful to our ______ (healthy).

The sentence requires a noun to complete the prepositional phrase "to our ______". "Healthy" is an adjective, so we need to use its noun form "health".

health

Smoking poses severe risks to human health by damaging multiple organ systems. The World Health Organization estimates tobacco use causes over 8 million deaths annually, with lung cancer, cardiovascular diseases, and respiratory illnesses being the primary killers. Even secondhand smoke exposure increases non-smokers' risk of heart disease by 25-30% and lung cancer by 20-30%. Protecting one's health starts with avoiding tobacco in all forms.