Could combustion-generated nanoparticles induce cytotoxicity also at the extremely low doses typical of indoor environments?

Summary: The presence of nanoparticles in the environment is mainly attributed to outdoor sources but sub-10 nm particles may also form indoor as effect of domestic activities such as cooking, heating, air freshening. Today, due to the COVID-19 pandemic, people are staying home for longer periods of times, thus being exposed to a poor indoor air quality. Due to elevated numerical concentration and large surface area, the health effect of sub-10 nm particles can go beyond what expected from their low mass concentration in the atmosphere. The objective of this study is to find, based on analysis of recent in vitro studies, a dose-effect correlation based on particle size/surface more than on particle mass. Such a correlation cold be useful to assess the health effects of people exposed to very low mass doses of nanoparticles either indoor or outdoor.