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OH and HO2 profiles measured in a real environment have been compared to the results of the INCA-Indoor model to improve our understanding of indoor chemistry. Significant levels of both radicals have been measured and their profiles display similar diurnal behavior, reaching peak concentrations during direct sunlight (up to 1.6×106 and 4.0×107 cm−3 for OH and HO2, respectively). Concentrations of O3, NOx, volatile organic compounds ( VOCs), HONO, and photolysis frequencies were constrained to the observed values. The HOx profiles are well simulated in terms of variation for both species (Pearson's coefficients: pOH=0.55, pHO2=0.76) and concentration for OH (mean normalized bias error: MNBEOH=−30%), HO2 concentration being always underestimated ( MNBEHO2=−62%). Production and loss pathways analysis confirmed HONO photolysis role as an OH precursor (here up to 50% of the production rate). HO2 formation is linked to OH-initiated VOC oxidation. A sensitivity analysis was conducted by varying HONO, VOCs, and NO concentrations. OH, HO2, and formaldehyde concentrations increase with HONO concentrations; OH and formaldehyde concentrations are weakly dependent on NO, whereas HO2 concentrations are strongly reduced with increasing NO. Increasing VOC concentrations decreases OH by consumption and enhances HO2 and formaldehyde. [ABSTRACT FROM AUTHOR]

This work presents an original method to identify priority indoor air pollutants in office buildings. It uses both a chronic risk assessment approach by calculating a hazard quotient, and a hazard classification method based on carcinogenic, mutagenic, reprotoxic, and endocrine disruptive effects. A graphical representation of the results provides a comprehensive and concise visualization of all of the information, including the number of buildings where each substance was measured, an indicator of exposure data robustness. Seventy-one out of 342 substances (20%) for which indoor air concentrations have already been measured in office buildings were identified as priority pollutants. The results were compared to previous prioritization studies in various types of indoor environments to assess the reliability of the method and highlight its advantages. Sensitivity analyses were performed to reduce the geographical scope (OECD countries only), time scope (after 2010 only), and measurement duration (working hours only) and showed little influence on the results. Finally, 123 additional substances that could be present in office indoor air but could not be assessed due to the lack of measurement data are proposed for future monitoring surveys to update the prioritization of indoor air pollutants in offices., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

OH and HO 2 profiles measured in a real environment have been compared to the results of the INCA-Indoor model to improve our understanding of indoor chemistry. Significant levels of both radicals have been measured and their profiles display similar diurnal behavior, reaching peak concentrations during direct sunlight (up to 1.6×10 6 and 4.0×10 7  cm -3 for OH and HO 2 , respectively). Concentrations of O 3 , NO x , volatile organic compounds (VOCs), HONO, and photolysis frequencies were constrained to the observed values. The HO x profiles are well simulated in terms of variation for both species (Pearson's coefficients: p OH =0.55, p HO 2 =0.76) and concentration for OH (mean normalized bias error: MNBE OH =-30%), HO 2 concentration being always underestimated (MNBE HO 2 =-62%). Production and loss pathways analysis confirmed HONO photolysis role as an OH precursor (here up to 50% of the production rate). HO 2 formation is linked to OH-initiated VOC oxidation. A sensitivity analysis was conducted by varying HONO, VOCs, and NO concentrations. OH, HO 2 , and formaldehyde concentrations increase with HONO concentrations; OH and formaldehyde concentrations are weakly dependent on NO, whereas HO 2 concentrations are strongly reduced with increasing NO. Increasing VOC concentrations decreases OH by consumption and enhances HO 2 and formaldehyde., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)