Comparative characteristics of relative pollution exposure caused by human surface chemical reaction under mixing and displacement ventilation

Wang, Jun; Yang, Jie; Yu, Jiang; Xiong, Feng

doi:10.1016/j.buildenv.2018.01.044

Cited by 9 publications

(7 citation statements)

References 11 publications

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“…A second possibility is a shift within the Criegee pathways at the higher ozone concentrations to reaction products that were not being measured. Materials with a higher degree of soiling (i.e., higher squalene loadings), such as unwashed hair, exhibit higher emission rates of products, such as acetone and 6-MHO, with yields increasing per unit of ozone consumed by human surface reactions. ,,− Ventilation type, such as mixing or displacement ventilation, can affect the concentration gradient and distribution of ozone in the room by changing the air flow pattern and speed. , Wang et al found that the maximum variation range for the breathing zone to bulk air ratios for the overall SqOz reaction product concentrations were 1.54–2.00 and 1.12–1.69 under mixing and displacement ventilation systems, respectively. The authors did not report the ratios for individual reaction products.…”

Section: The Sqoz Reactionmentioning

confidence: 99%

“…AER, or the number of times the air volume in an enclosed space is replaced per hour, influences indoor air chemistry. Gas-phase reactions are sensitive to AER, consuming more ozone at lower AERs compared to higher AERs and resulting in higher SqOz volatile and particle product concentrations. ,,,,,,,,, Many authors note that while the buildup of indoor reaction products in the indoor air, and therefore the resulting exposure, would decrease with increased AER since there is more dilution of indoor emissions by outdoor air at higher AER, but ozone exposure would increase due to increased replenishment from outdoor air. − , As AER decreases, indoor product concentrations derived from gas-phase ozone chemistry generally increase even though indoor ozone concentrations decrease …”

Section: Conditions Affecting the Sqoz Reactionmentioning

confidence: 99%

“… 26 , 41 , 90 − 93 Ventilation type, such as mixing or displacement ventilation, can affect the concentration gradient and distribution of ozone in the room by changing the air flow pattern and speed. 93 , 94 Wang et al 93 found that the maximum variation range for the breathing zone to bulk air ratios for the overall SqOz reaction product concentrations were 1.54–2.00 and 1.12–1.69 under mixing and displacement ventilation systems, respectively. The authors did not report the ratios for individual reaction products.…”

Section: The Sqoz Reactionmentioning

confidence: 99%

“… 17 , 63 , 78 , 88 , 90 , 92 , 97 The increased product concentrations occur both near the body in the breathing zone as well as in bulk room air. 92 , 93 In general, as the ozone concentration increased, there was a shift in the products formed from predominantly aldehydes to a mixture of various ketones, aldehydes, and alcohols. 57 This shift is possibly due to increased secondary oxidation products or secondary ozonides with various C–O functionalities due to additional ozone reactions with unsaturated aldehydes.…”

Section: Conditions Affecting the Sqoz Reactionmentioning

confidence: 99%

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Reactions and Products of Squalene and Ozone: A Review

Coffaro

Weisel

2022

Environ. Sci. Technol.

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This critical review describes the squalene-ozone (SqOz) reaction, or squalene ozonolysis. Ambient ozone penetrates indoors and drives indoor air chemistry. Squalene, a component of human skin oil, contains six carbon–carbon double bonds and is very reactive with ozone. Bioeffluents from people contribute to indoor air chemistry and affect the indoor air quality, resulting in exposures because people spend the majority of their time indoors. The SqOz reaction proceeds through various formation pathways and produces compounds that include aldehydes, ketones, carboxylic acids, and dicarbonyl species, which have a range of volatilities. In this critical review of SqOz chemistry, information on the mechanism of reaction, reaction probability, rate constants, and reaction kinetics are compiled. Characterizations of SqOz reaction products have been done in laboratory experiments and real-world settings. The effect of multiple environmental parameters (ozone concentration, air exchange rate (AER), temperature, and relative humidity (RH)) in indoor settings are summarized. This critical review concludes by identifying the paucity of available exposure, health, and toxicological data for known reaction products. Key knowledge gaps about SqOz reactions leading to indoor exposures and adverse health outcomes are provided as well as an outlook on where the field is headed.

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Section: The Sqoz Reactionmentioning

confidence: 99%

Section: Conditions Affecting the Sqoz Reactionmentioning

confidence: 99%

Section: The Sqoz Reactionmentioning

confidence: 99%

Section: Conditions Affecting the Sqoz Reactionmentioning

confidence: 99%

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Reactions and Products of Squalene and Ozone: A Review

Coffaro

Weisel

2022

Environ. Sci. Technol.

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“…DV could bring about more significant changes under the same chemical reaction conditions on human surface. However, when ventilation rate exceeded a certain value, the number of droplets suspending and escaping throughout the room did not change much [ 99 ]. When ACH reached 12 h −1 , DV and MV systems achieved similar levels of pollutants exposure [ 88 ].…”

Section: Impacts On Thermal Comfort Air Quality and Virus Spread Controlmentioning

confidence: 99%

A review of different ventilation modes on thermal comfort, air quality and virus spread control

Fan

Wang

et al. 2022

Building and Environment

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In the era of Corona Virus Disease 2019 (COVID-19), inappropriate indoor ventilation may turn out to be the culprit of microbial contamination in enclosed spaces and deteriorate the environment. To collaboratively improve the thermal comfort, air quality and virus spread control effect, it was essential to have an overall understanding of different ventilation modes. Hence, this study reviewed the latest scientific literature on indoor ventilation modes and manuals of various countries, identified characteristics of different ventilation modes and evaluated effects in different application occasions, wherefore to further propose their main limitations and solutions in the epidemic era. For thermal comfort, various non-uniform ventilation modes could decrease the floor-to-ceiling temperature difference, draft rate or PPD by 60%, 80% or 33% respectively, or increase the PMV by 45%. Unsteady ventilation modes (including intermittent ventilation and pulsating ventilation) could lower PPD values by 12%–37.8%. While for air quality and virus spread control, non-uniform ventilation modes could lower the mean age of air or contaminants concentration by 28.3%–47% or 15%–47% respectively, increase the air change efficiency, contaminant removal effectiveness or protection efficiency by 6.6%–10.4%, 22.6% or 14%–50% respectively. Unsteady ventilation mode (pulsating ventilation) could reduce the peak pollutant concentration and exposure time to undesirable concentrations by 31% and 48% respectively. Non-uniform modes and unsteady modes presented better performance in thermal comfort, air quality and virus spread control, whereas relevant performance evaluation indexes were still imperfect and the application scenarios were also limited.

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