noun
public health studies; public health science
Academic discipline focusing on public health, epidemiology, and community medicine.
彼女は大学で公衆衛生学を専攻している。
She is majoring in public health studies at university.
公衆衛生 is the general concept of public health, while 公衆衛生学 specifically refers to the academic study or science of public health.
Compound of 公衆 (public) + 衛生 (hygiene/health) + 学 (study/science).