biostudies-literatureLakey PSJAlfred P. Sloan Foundation110https://www.ebi.ac.uk/biostudies/studies/S-EPMC9814873biostudies-literatureUnknown4(1)Historically air constituents have been assumed to be well mixed in indoor environments, with single point measurements and box modeling representing a room or a house. Here we demonstrate that this fundamental assumption needs to be revisited through advanced model simulations and extensive measurements of bleach cleaning. We show that inorganic chlorinated products, such as hypochlorous acid and chloramines generated via multiphase reactions, exhibit spatial and vertical concentration gradients in a room, with short-lived ⋅OH radicals confined to sunlit zones, close to windows. Spatial and temporal scales of indoor constituents are modulated by rates of chemical reactions, surface interactions and building ventilation, providing critical insights for better assessments of human exposure Communications chemistrySpatial and temporal scales of variability for indoor air constituents.PMC9814873G-2019-12306G-2020-13912Lakey PSJBottorff BKahan TFShaw DWang CZhou SRim DOsterstrom FFStevens PSCarslaw NRosales CWon YMattila JAbbatt JPDAmpollini LFarmer DKNovoselac ADeCarlo PFShiraiwa MReidy EfalseSpatial and temporal scales of variability for indoor air constituents.Historically air constituents have been assumed to be well mixed in indoor environments, with single point measurements and box modeling representing a room or a house. Here we demonstrate that this fundamental assumption needs to be revisited through advanced model simulations and extensive measurements of bleach cleaning. We show that inorganic chlorinated products, such as hypochlorous acid and chloramines generated via multiphase reactions, exhibit spatial and vertical concentration gradients in a room, with short-lived ⋅OH radicals confined to sunlit zones, close to windows. Spatial and temporal scales of indoor constituents are modulated by rates of chemical reactions, surface interactions and building ventilation, providing critical insights for better assessments of human exposure 2021-01-01T00:00:00Z2021 Aug2025-04-06T19:39:54.638Z2025-04-06T19:39:54.638ZS-EPMC98148733669755110.1038/s42004-021-00548-5