The difference in exposure to secondhand smoke/aerosol indoors and outdoors is that indoors the concentration of the harmful chemicals, compounds, and particles released from the product or exhaled by the smoker/vaper may build up and/or stay in the enclosed space for longer periods of time, which means persons near the smoker/vaper indoors may be exposed to higher concentrations of the contaminants for longer durations.
Regardless of where the exposure takes place — outside or inside, secondhand exposure may pose health risks or worsens existing health symptoms for some people.
Read more about Secondhand Smoke/Aerosol.