Real-Time Measurements of Botanical Disinfectant Emissions, Transformations, and Multiphase Inhalation Exposures in Buildings

Abstract

Thymol-based botanical disinfectants have emerged as natural alternatives to traditional chemical disinfectants given their effectiveness as antimicrobial pesticides and ability to inactivate SARS-CoV-2. This study investigates the impact of botanical disinfectants on indoor air chemistry and human exposure. Controlled surface disinfection experiments were conducted in a mechanically ventilated zero-energy tiny house laboratory. Volatile organic compounds (VOCs) and aerosol size distributions were measured in real-time (1 Hz) with a proton transfer reaction time-of-flight mass spectrometer and a highresolution electrical low-pressure impactor, respectively. Botanical disinfectant spray and wipe products drove sudden changes in the chemical composition of indoor air. Mixing ratios of monoterpenes (C 10 H 16 ) and monoterpenoids (C 10 H 14 O, C 10 H 16 O, C 10 H 18 O, and C 10 H 20 O) increased suddenly during the disinfection events (10 −1 to 10 2 ppb) and exhibited volatility-dependent temporal emission profiles. VOC emission factors ranged from 10 0 to 10 4 μg g −1 , and thymol intake fractions ranged from 6 to 7 × 10 3 ppm. Rapid new particle formation events were observed due to ozonolysis of monoterpenes and monoterpenoids, increasing sub-100 nm particle number concentrations by 10 4 to 10 5 cm −3 . Botanical disinfectant sprays initiated multiphase inhalation exposure to VOCs, secondary organic aerosol, and sub-10 μm droplets, with large deposited doses in each respiratory tract region associated with the latter two.

High time‐resolution measurements of ultrafine and fine woodsmoke aerosol number and surface area concentrations in biomass burning kitchens: A case study in Western Kenya

“…The range in indoor PN (10 3 to >10 6 /cm 3 ) and PSA (10 2 –10 5 μm 2 /cm 3 ) concentrations can inform the suitability of field sampling strategies for monitoring woodsmoke aerosol size distributions via electrical mobility and aerodynamic size classification techniques. PN and PSA size distributions can be coupled with deposition fractions for the human respiratory tract to estimate inhaled deposited dose rates 113–116 …”

“…Though the common ways of deciding original and improved stove tiers based on mass metrics, such as PM 1 , PM 2.5 , elemental carbon, and brown carbon, are highly systematic and widely effective for comparing cooking environments with the same stove types, 25 it is clear that cookstoves with improved combustion such as rocket, gasifier, and air injection have the potential to release a greater abundance of particles smaller than 30 nm relative to TSFs (exemplified in distributions can be coupled with deposition fractions for the human respiratory tract to estimate inhaled deposited dose rates. [113][114][115][116] The field measurements in the Nandi kitchens can guide the development and application of low-cost aerosol sensing technologies for deployment in biomass burning environments. There has been significant research on the design, assessment, and use of low-cost optical particle counters, however, such sensors cannot reliably detect sub-300 nm particles.…”

Chemistry and human exposure implications of secondary organic aerosol production from indoor terpene ozonolysis

“…2A); this is 140 to 190 times more than the peak outdoor monoterpene mixing ratios observed outside the research building for this day (~2 ppb). While indoor mixing ratios depend on a variety of factors, including the AER, cleaning solution concentrations, and cleaning surface area, the limonene mixing ratios observed in this study were approximately 1.3 to 2.2 times more than a lemon-scented furniture polish (wax) application to a coffee table inside a 25-m 3 chamber (15), about 1.8 to 2.4 times more than the peak limonene concentration from a household product used in a 50-m 3 chamber (11), approximately 20 times more than the peak indoor mixing ratios previously observed in an Australian classroom (~17 ppb) (13), 3.7 to 5 times more than monoterpene emissions from botanical disinfectants sprayed onto a glass kitchen countertop (32), and about 56 to 76 times more than the peak mixing ratios observed during the HOMEChem field campaign (~5 ppb) (33), where similar mopping experiments using a monoterpene-based cleaner were done. The volume of the HOMEChem test house was larger (250 m 3 ) as compared to the room used in this study (~50 m 3 ); thus, the emissions from the mopping events dispersed into a larger volume, resulting in lower concentrations during the mopping episode.…”

Detecting residual chemical disinfectant using an atomic Co–Nx–C anchored neuronal-like carbon catalyst modified amperometric sensor

“…4 Hydrogen peroxide (H 2 O 2 ) is recognized as one of the most reliable disinfectants for sterilization and reuse of PPE. [5][6][7][8] It has been demonstrated that H 2 O 2 vapor (especially after ionization) could kill 100% influenza A virus (having similar virological characteristics as coronaviruses) on N95 masks in 60 minutes, 9 or kill >99.9999% Geobacillus stearothermophilus spores (more resistant to killing with H 2 O 2 than most viruses) on surfaces of PPE in 100 minutes. 10 However, H 2 O 2 residues on such inadequately rinsed medical instruments and PPE would cause a health risk for wearers.…”

“…9,11 The US Centers for Disease Control has listed upper airway irritation, inflammation of the nose, hoarseness, shortness of breath and tightening of the chest as possible reactions to inhalation of even low levels of H 2 O 2 . 8,12 It has been emphasized not to use face masks immediately after H 2 O 2 disinfection because of the residual oxidant. The removal process of residual H 2 O 2 usually consumes 2-18 hours to ensure that the residual oxidant was below the safety limit (1 ppm), 9,13 whereas the overlong process is undesirable due to energy consumption, spatial occupation, and time constraints raised by an emergency like COVID-19.…”