Indoor heterogeneous photochemistry of molds and their contribution to HONO formation. (5th December 2021)

• Record Type: Journal Article
• Authors: Kalalian, Carmen; Depoorter, Antoine; Abis, Letizia; Perrier, Sébastien; George, Christian
• Is Part Of: Indoor air. Volume 32:Number 1(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-05
• Subjects: Aspergillus niger -- indoor air quality -- microbial surfaces -- nitrous acid -- photochemistry -- Volatile Organic Compounds; Indoor air pollution -- Periodicals; Sick building syndrome -- Periodicals; Ventilation -- Periodicals; 613.5
• DOI: 10.1111/ina.12971
• Languages: English
• ISSNs: 0905-6947

Abstract

Abstract: To better understand the impact of molds on indoor air quality, we studied the photochemistry of microbial films made by Aspergillus niger species, a common indoor mold. Specifically, we investigated their implication in the conversion of adsorbed nitrate anions into gaseous nitrous acid (HONO) and nitrogen oxides (NOx ), as well as the related VOC emissions under different indoor conditions, using a high‐resolution proton transfer reaction‐time of flight‐mass spectrometer (PTR‐TOF‐MS) and a long path absorption photometer (LOPAP). The different mold preparations were characterized by the means of direct injection into an Orbitrap high‐resolution mass spectrometer with a heated electrospray ionization (ESI‐Orbitrap‐MS). The formation of a wide range of VOCs, having emission profiles sensitive to the types of films (either doped by potassium nitrate or not), cultivation time, UV‐light irradiation, potassium nitrate concentration and relative humidity was observed. The formation of nitrous acid from these films was also determined and found to be dependent on light and relative humidity. Finally, the reaction paths for the NOx and HONO production are proposed. This work helps to better understand the implication of microbial surfaces as a new indoor source for HONO emission.