Complex sentence: Surgical masks are also used by the general public in heavily populated East Asia countries to reduce the chance of spreading airborne diseases; in Japan, it is common to wear a face mask whilst ill to avoid infecting others in public settings.
Split into simpler sentences: Surgical masks are also used by the general public in heavily populated countries in East Asia to reduce the chance of spreading airborne diseases. In Japan, it is common to wear a face mask whilst ill to avoid infecting others in public settings.