(Journal of the Air & Waste Management Association) This study measured nitrogen dioxide concentrations in indoor and outdoor environments and compared them to personal exposures in 18 cities in 15 countries around the world. Personal nitrogen dioxide exposures were more strongly correlated with indoor concentrations than with outdoor concentrations. The use of a gas stove in the home was found to be the dominant factor influencing nitrogen dioxide concentrations, with a 67% increase in mean personal nitrogen dioxide exposure. These associations indicate the global nature of the correlation between personal nitrogen dioxide exposures and indoor sources, such as gas stoves or space heaters, demonstrating that this relationship is not dependent on country-specific parameters.
J.I. Levy (1998) Impact of Residential Nitrogen Dioxide Exposure on Personal Exposure: An International Study, Journal of the Air & Waste Management Association, 48:6, 553-560, https://www.tandfonline.com/doi/abs/10.1080/10473289.1998.10463704