Air Exposure Time Research Articles

Effect of air exposure time on erodibility of intertidal mud flats

This study investigates the influence of air exposure time on the erodibility of intertidal mud flats, emphasizing the role of evaporation in altering sediment strength and cohesion. Through a comprehensive approach combining laboratory experiments, fieldwork, and numerical modelling, it explores the dynamic interactions between sediment properties and environmental conditions. The research reveals that drying significantly reduces sediment erodibility, with pronounced effects observed during the initial hours of air exposure. Laboratory tests demonstrate a direct correlation between drying time and increased yield stress for both artificial and field-derived mud samples. Field observations further support these results, showing spatial and temporal variations in water content and shear strength across various locations on a tidal flat. The study emphasizes the critical impact of mud content on water retention and the subsequent effect on sediment stability. The incorporation of drying time into erosion formulations within a numerical model highlights the importance of considering evaporation processes in predicting the morphological evolution of tidal flats. This research contributes to a better understanding of sediment transport dynamics in intertidal zones, offering insights into the mechanisms driving the growth and stability of mud flats. It underscores the necessity of integrating evaporation effects into cohesive sediment transport models to enhance the accuracy of predictions concerning the erosion and accretion of intertidal environments.

Observation of the early stages of environmental contamination in graphene by friction force.

Exposure to ambient air contaminates the surface of graphene sheets. Contamination may arise from different sources, and its nature alters the frictional behavior of the material. These changes in friction enable the observation of the early stages of contaminants' adsorption in graphene. Using a friction force microscope, we show that molecular adsorption initiates at the edges and mechanical defects in the monolayer. Once the monolayer is covered, the contaminants spread over the additional graphene layers. With this method, we estimate the contamination kinetics. In monolayer graphene, the surface area covered with adsorbed molecules increases with time of air exposure at a rate of 10-14m2/s, while in bilayer graphene, it is one order of magnitude smaller. Finally, as the contaminants cover the additional graphene layers, friction no longer has a difference concerning the number of graphene layers.

Magnetotransport and Shubnikov-de Haas oscillations in LaBi samples with different degrees of air exposure

A series of magnetotransport experiments has been designed to investigate single-crystalline LaBi samples subjected to different degrees of air exposure. As the air exposure time increases, the temperature-dependent resistance changes from the typical behaviour of a good metal to that of a bad metal, exhibiting a negative temperature coefficient. Additionally, the magnetoresistance in the sample with the longest air exposure becomes linear in the magnetic field, instead of the ubiquitous quadratic magnetoresistance observed in many other related rare-earth monopnictides. Despite these drastic changes, the Shubnikov–de Haas oscillations remain almost unaffected by air exposure — the frequency spectra and the effective masses do not vary as the air exposure time increases. Our results suggest the existence of two separate contributions to the transport data: one from the surface and the other from the bulk. Given the topological nature of LaBi, our results suggest controlled air exposure provides an effective means to distinguish between surface and bulk states.

High-performance PES ultrafiltration membrane with sponge-like structure assisted by N-vinylpyrrolidone

The study focused on the preparation of spongy polyether sulfone (PES) ultrafiltration membrane and investigated the effects of N-vinylpyrrolidone (NVP) and air exposure time on membrane properties. NVP was used as a pore-forming additive to create interconnected pores in the membrane structure, leading to higher water permeability. Furthermore, longer air exposure generally improved membrane porosity and performance. However, excessive exposure led to membrane shrinkage and reduced mechanical strength. The incorporation of NVP and air exposure effectively mitigates the trade-off effect between permeability and selectivity. this work might provide an effective process for preparing spongy PES ultrafiltration membrane with outstanding antifouling performance, high throughput, and great stability. Therefore, an optimized composite membrane was confirmed by combining the addition of 10 wt% NVP with 40 s air exposure, referred to as M4. The water flux of the M4 membrane reached 797.62 L·m−2·h−1, which was 1.9 times higher than that of a pure PES membrane. Additionally, the rejection rate of bovine serum albumin (BSA) increased from 57.97 % to 95.89 % compared to the pure PES membrane. The spongy PES ultrafiltration membrane exhibited desirable properties for protein separation and wastewater treatment, making them promising materials for various applications in the field.

Degradation of cathode in air and its influences on direct recycling

Delamination has been widely used in direct recycling of spent lithium-ion batteries (LIBs) as the first step to harvest cathode materials from cathodes. The variations of the recycling performance have been documented in many studies. The main mechanism of delamination is the inactivation of bonding forces provided by the polyvinylidene fluoride (PVDF) binder. It is believed that the storage environment (air exposure time) will affect the performances of delamination to some extent. Three representative methods (direct calcination, pressure washing, and NMP solvent extraction) for delamination were studied to elucidate the effect of air exposure time on delamination efficiency. The peel-off efficiency (98–99%) of the direct calcination method was barely influenced by air exposure time. The pressure washing system or NMP solvent extraction method also exhibited high peel-off efficiency using samples after a long air exposure time (1 month), however these methods may have problems regarding Al contamination, i.e., 11.5 mg/g of pressure washing system and 134.4 mg/g of NMP solvent extraction. Results suggest that enhanced adhesion (0.11 MPa/month) could be a potential reason why air contact time affects delamination, with O2 and/or H2O acting as contributors. This finding may help to maximum performance of delamination, as it highlights the importance of storage conditions of the spent LIBs prior to direct recycling.

Enhancing minority carrier lifetime in Ge: Insights from HF and HCl cleaning procedures

Efficiently passivating germanium (Ge) surfaces is crucial to reduce the unwanted recombination current in high-performance devices. Chemical surface cleaning is critical to remove surface contaminants and Ge oxides, ensuring effective surface passivation after dielectric deposition. However, Ge oxides can rapidly regrow upon air exposure. To understand the surface evolution after wet cleaning, we present a comprehensive study comparing HF and HCl deoxidation steps on p-type Ge surfaces and monitor the surface as a function of air exposure time. Distinct oxide regrowth dynamics are observed: HF-treated samples exhibit swift regrowth of all Ge oxide states, whereas HCl-treated Ge surfaces exhibit a lower concentration of low degrees of oxidation and slower or no regrowth of high oxide states even after 110 min of air exposure. In addition, the presence of Ge–Cl bonds induces different oxidation dynamics compared to the Ge–OH bonds resulting from HF cleaning. This leads to varying surface electronic band structures, with HF-treated Ge exhibiting a strong positive band bending (+0.20 eV). Conversely, HCl-treated samples display a lower band curvature (+0.07 eV), mostly due to the presence of Ge–Cl bonds on the Ge surface. During air exposure, the increased GeOx coverage significantly reduces the band bending after HF, while a constant band bending is observed after HCl. Finally, these factors induce a reduction in the surface recombination velocity after wet etching. Combining both chemical and field-induced passivation, HF-treated Ge without rinsing exceeds 800 μs.

Trawl-related mortality and injuries to the southern king crab Lithodes santolla of Patagonia

The catch and discard of non-target species could have detrimental effects on bycatch, species due, among others, to the increase in mortality and prevalence of injuries. In Argentina, the southern king crab (SKC), Lithodes santolla, supports a profitable trap fishery but is also caught as bycatch in trawl fisheries. The aims of this work were: i) to quantify the mortality and injuries in SKC caught as bycatch in the hake fishery in San Jorge Gulf (southwestern Atlantic Ocean), ii) to assess the factors that affect their mortality and injury occurrence, and iii) to estimate their postdiscard mortality.Immediate mortality (IM) and injuries in SKC were recorded in hauls of the hake fishery, and then related to operational and biological variables. SKC vitality was assessed using the reflex action mortality predictor (RAMP) test. Postdiscard mortality was analyzed in aquaria and wild (sea cages) conditions. The IM of SKC in the common hake fishery was 31%. The IM, as well as increased injuries and decreased vitality, were directly associated with the time and conditions of air exposure. Both the IM and injury occurrence were also affected by biological variables such as the sex,size and molt stage. Postdiscard mortality was lower in wild conditions than in the aquaria (1%). Our results suggest that SKC could have high resistance to handling and high recovery capacity after its return to the sea. In consequence, the quick return of SKC to the sea may have a positive effect on SKC survival.

Polymer-derived SiAlOC coating to improve the high-temperature resistance of chromium

Cr and its alloys are interesting materials for applications at temperatures higher than 1000 °C. However, challenges such as limited oxidation resistance and nitridation still restrict their usage as high-temperature structural materials. The present work investigates the influence of a 0.6 μm thin SiAlOC sol-gel coating on the oxidation resistance and kinetic of Cr at 950 °C for 50 h and 1050 °C for up to 100 h of exposure time in dry synthetic air using thermogravimetric analysis. The resulting oxide scale and microstructure were extensively studied by combining different techniques such as EPMA, XRD, SEM, Raman spectroscopy, FT-IR, and STEM. Overall, a reduction in mass gain and an improved scale adhesion was observed. The interaction of coating and substrate causing nanosized Cr2O3 and cristobalite formation in the SiAlOC coating was further supported by investigations of bulk materials.

Meat Quality Changes in Aged Pork Loin using Jeju Volcanic Scoria Earthenware.

This study aimed to investigate changes in the quality of meat aged using Jeju scoria earthenware. Water-holding properties, pH, color, tenderization, fatty acid composition, and free amino acid characteristics of aged pork loin were evaluated to determine the effects of wet and dry (normal and Jeju Scoria) aging methods and aging time (0, 10, 20, 30, and 40 days) on meat quality. The aging methods altered pH and CIE L* after 10 days of aging. However, the aging method did not alter the pH and CIE L* of the aged pork loin after 10 days of aging. The shear force was significantly lower in the Scoria aging method than in the wet aging method after 10 and 20 days of aging. Both the normal and Scoria aging methods increased aging loss compared to the wet aging method, which could be attributed to longer air exposure times of the two non-packaged aging methods than in the packaged aging method. The scoria aging method had significantly higher contents and ratios of saturated (SFA) to mono-unsaturated fatty acids but lower ratios of poly-unsaturated fatty acids to SFA than the wet aging method. The content of most free amino acids significantly increased with aging time, especially those related to the sweet, and umami categories. In summary, this study suggests that the Scoria aging method provides positive aspects of eating quality, such as improvement of meat tenderness and taste, including umami, with minimum changes in the overall meat quality.

Evaluating Fermentation Quality, Aerobic Stability, and Rumen-Degradation (In Situ) Characteristics of Various Protein-Based Total Mixed Rations.

The purpose of this experiment was to evaluate changes in fermentation quality, chemical composition, aerobic stability, anti-nutritional factors, and in situ disappearance characteristics of various protein-based total mixed rations. Soybean meal (control, non-fermented), fermented cottonseed meal (F-CSM), and fermented rapeseed meal (F-RSM) group were used to prepare the TMRs with corn, whole-plant corn silage, corn stalks, wheat bran, and premix. The test groups were inoculated at 50% moisture with Bacillus clausii and Saccharomyces cariocanus and stored aerobically for 60 h. The nylon-bag method was used to measure and study the rumen's nutrient degradation. The pH of all TMRs after 48 h of air exposure was below 4.8, whereas that of the F-CSM and control and F-RSM groups increased to 5.0 and >7.0, respectively. After 8 h of aerobic exposure, the temperatures of all groups significantly increased, and 56 h later, they were 2 °C higher than the surrounding air. The lactic acid concentration in the F-CSM and F-RSM groups increased after 12 h of aerobic exposure and then decreased. The acetic acid concentrations in the fermented groups decreased significantly with the increasing air-exposure time. The yeast population of the TMRs increased to more than 8.0 log10 CFU/g before 72 h of air exposure, followed by a decrease in the population (5.0 log10 CFU/g). After fermentation, the free gossypol (FG) concentration in F-CSM decreased by half and did not change significantly during the air-exposure period. Fermentation with probiotics also reduced the F-RSM's glucosinolate concentration, resulting in a more than 50% detoxification rate. Compared with the F-CSM and F-RSM groups, the effective degradation rates of nutrients in the control group were the lowest, and the dry matter (DM), crude protein (CP), natural detergent fiber (NDF), and acid detergent fiber (ADF) all degraded effectively at rates of 28.4%, 34.5%, 27.8%, and 22.8%, respectively. Fermentation with B. clausii and S. cariocanus could improve the fermentation quality and nutrient composition, decrease the anti-nutritional factor, and increase nutrient degradation of the TMR with cottonseed meal or rapeseed meal as the main protein source, thus achieving detoxification.

Mechanism of residue formation on Ge-rich germanium antimony tellurium alloys after plasma etching

In phase-change random access memory (PCRAM) applications, the germanium antimony tellurium alloy (GST) is patterned using halogen etching in inductively coupled plasma reactors. This paper focuses on the surface state evolution of an optimized Ge-rich GST material after plasma etching. Four hours after etching, big dome-shaped residues are observed on PCRAM structures. Their number and size increase with the time of air exposure. X-ray photoelectron spectroscopy and energy-dispersive x-ray spectroscopy analyses reveal an important germanium oxidation on the surface with residues. Their formation is then investigated. Complementary analyses highlight that the moisture environment has a catalytic effect on the residue formation. Based on this study, a detailed mechanism responsible for residue formation is proposed.

Qualitative Assessment of Off-Gassing of Compounds from Field-Contaminated Firefighter Jackets with Varied Air Exposure Time Intervals Using Headspace GC-MS.

Firefighters are exposed to a complex mix of volatile and semi-volatile compounds from burning construction materials, consumer products, and other elements during fire suppression and rescue. These compounds can be absorbed onto the gear worn by firefighters and, depending on their volatility, can be released from the gear under different conditions. Few studies have focused on the off-gassing of toxic compounds from firefighters' gear, particularly in terms of qualitative analysis methods. This study introduces a novel qualitative analysis method using headspace gas chromatography-mass spectrometry (HS-GC-MS) to assess off-gassing from field-contaminated jackets at regular intervals. Our findings show that certain compounds, such as acetic acid and di-ethyl-hexyl-phthalate (DEHP), remained present even after the gear were allowed to air out for 48 h. The persistent off-gassing of chemicals, even under ambient conditions, raises concerns about potential hazards that could pose risks for personnel in the vicinity of contaminated gear, including inside fire stations. The implications of these findings extend beyond fire stations and may have significant public health implications for firefighters who are repeatedly exposed to these compounds over time.

Chronic handling stress in zebrafish Danio rerio husbandry.

The zebrafish (Danio rerio, Hamilton, 1822) is one of the most important fish model species in scientific research, with millions of fish housed in laboratory animal facilities around the world. During husbandry, it is necessary to regularly handle the fish, which could cause short- and long-term stress, possibly affecting both fish welfare and experimental outcomes. In two experiments, the authors studied effects of transferring adult zebrafish, by chasing them with a net and/or exposing them to air (netting) on different endpoints: cortisol levels, reproduction parameters and behavioural parameters. They used realistic chase and air-exposure times to mimic normal zebrafish husbandry and investigated the potential to habituate to handling stressors. Finally, the potential welfare improvements of a nutritional reward after handling were studied. All types of handling induced a stress response, but the authors did not find a correlation with the intensity of the stressor. Realistic (short) handling routines also caused stress, both after the first time and after regular handling over a long period of time. Cortisol levels peaked after 15 min, were still elevated after 30 min and dropped to resting level after 60 min. This should be taken into account by researchers when carrying out measurements or behavioural trials within an hour after handling. There is a minor potential benefit of nutritional rewards that may contribute to a faster recovery of normal behaviour. They did not find evidence of habituation to chasing and netting stress. Taking the stress response after handling into consideration will improve fish welfare and health and minimise husbandry-associated sources of variation.

Oxidative stress in juvenile tambaqui (Colossoma macropomum) after different periods of air exposure

This study evaluated the response of juvenile Colossoma macropomum to oxidative stress when exposed to air for different periods of time. Fifty-four juveniles weighing 74.8 ± 17.4 g were randomly transferred to nine 30-L tanks in a recirculating aquaculture system and acclimatized to experimental conditions for 15 days. The fish were subsequently fasted for 24 h, after which a group of animals (n = 6) was sampled immediately at the beginning of the experiment to determine baseline levels (without air exposure). Another group (n = 24) was exposed to air for 30 min (30E) and the rest of the fish (n = 24) were exposed to air for 60 min (60E). Oxidative damage and antioxidant defenses were determined immediately after air exposure (IAE; n = 6) and at 1, 24 and 48 h after air exposure (1hAE, 24hAE, and 48hAE; n = 6 animals/per exposure time) by euthanizing fish and immediately removing the gills, liver, kidney, and brain. The interaction between factors (air exposure time x collection time) had an effect on reduced glutathione in the liver (P < 0.0001) and kidney (P = 0.0252). The highest concentrations for reduced glutathione in the gills was for treatment 60E (P = 0.0294), while that for the brain was for treatment 30E (P = 0.0012). Air exposure time had an effect on liver (P < 0.0001) and kidney (P < 0.0001) superoxide dismutase, with the highest values for 60E and 30E, respectively. The interaction between factors had an effect on liver protein levels (P = 0.0029), with the highest value for 30E at 24hAE. Treatment 60E had higher protein degradation in the gills, kidneys and brain than treatment 30E (P < 0.05). Treatment 30E had lower TBARS concentrations in the liver (P = 0.0284) and gills (P = 0.0012), but without damage to the kidney (P = 0.9396) and brain (P = 0.5277). Therefore, air exposure caused changes in antioxidant defenses in the liver, kidney, brain, and gills of C. macropomum juveniles.

Effect of the trap net emptying method on release mortality of Atlantic salmon estimated by a Bayesian system model

AbstractWe evaluated the effect of emptying techniques of a pontoon trap on mortality of Atlantic salmon on their spawning migration along the Finnish coast of the northern Baltic Sea by tagging and releasing fish from commercial trap nets. Two methods currently used, a traditional emptying chute and a lifting bag, were compared. The lifting bag has been developed primarily for minimising injuries for fish during emptying. A custom‐built Bayesian system model was used for mortality estimation. We also explored external injuries of salmon and compared the probability of getting an injury between the emptying methods. The mean probability of salmon dying due to release from a trap with an emptying chute was 24% (90% HDI 3%–43%), whereas that for salmon released from a trap with a lifting bag was 13% (90% HDI 1%–24%). Results showed a higher probability of injuries and longer air exposure time in salmon caught with a trap with an emptying chute, which may explain the observed difference in mortality. Manual handling of a lifting bag appears to pose a clear work safety risk for fishers. It is noteworthy that the role of release mortality for northern Baltic salmon stocks is small because the number of salmon released in coastal fishery is currently low.

Role of Graphene in Oxidation of Underlying Cu Substrates Elucidated through Angle-Resolved X-ray Photoelectron Spectroscopy: Implications for Corrosion Protection of Graphene/Cu

The role of single-layer graphene in the oxidation process of Cu substrates underlying graphene remains controversial, and the evolution of interfacial oxide layers of graphene/Cu (Gr/Cu) over time has not been reported. Qualitative and quantitative studies of the interfacial oxide layer of Gr/Cu samples upon exposure to ambient conditions for long periods are crucial for revealing the role of graphene in the oxidation process of underlying Cu substrates, so as to further promote the research on corrosion protection of copper surfaces. Angle-resolved X-ray photoelectron spectroscopy (ARXPS) is a practical characterization technology for studying the structure, composition, and thickness of interfacial oxide layers. In this work, we propose an extended model to elucidate the role of graphene in oxidation of underlying Cu substrates through ARXPS study of evolution of interfacial oxide layers. The thickness of an interfacial oxide layer is positively correlated with air exposure time, and it is thinner than that of an oxide layer on a Cu surface; the fractional coverage of the island-like interfacial oxide layer is within the range of 0.4–0.6. For Gr/Cu samples exposed to ambient conditions for less than 6 months, graphene can inhibit the formation of Cu2O, whereas it promotes the formation of CuO in the interfacial oxide layer for long-term oxidized Gr/Cu samples (≥12 months), leading to the embedded structure of the interfacial oxide layer. The results of this study can serve as a guide for the corrosion protection of copper-based devices.

Association between thermal comfort and cortisol depends on the air temperature and exposure time

Exploring the link between thermal comfort and cortisol, a stress hormone, at different air temperatures can give a theoretical basis for creating a comfortable and healthy indoor environment, although the relationship is not yet obvious. We considered three temperatures and two exposure levels, collected the subjects' subjective evaluations and saliva, detected the concentration of cortisol in saliva, and analyzed the change characteristics of subjective evaluations and cortisol concentration at different temperatures with exposure time and their relationships at different exposure times. Subjective evaluations were better and cortisol concentration was lower at neutral temperature, according to our findings. Furthermore, there was a U-shaped distribution of cortisol concentration with thermal sensation vote (TSV), and cortisol concentration decreased with increasing thermal comfort vote (TCV). In comparison to “hot” and “cold,” the concentration of cortisol corresponding to “neutral” after 30 min of exposure declined by 179.0% and 59.3%, respectively; the concentration for “very uncomfortable” was higher by 191.4% than for “comfortable.” Following a 60-min exposure, the concentrations that corresponded to “neutral” and “very uncomfortable” were, respectively, lower by 89.3% and 143.0% than “hot” and “comfortable.” Our findings suggest that cortisol derived from human saliva may be a novel and useful objective indicator assessing human thermal comfort. This study can deepen our understanding of the relationship between human thermal comfort and stress hormones, and relevant conclusions provide theoretical basis for building indoor thermal environment.

Gallic Acid-Reduced Graphene Oxide Deposited with Carbon Nanotubes for Transparent Film Heaters

The flexible transparent film heater described in this research was based on graphene, carbon nanotubes (CNTs), and polyethylene terephthalate (PET). Natural polyphenols gallic acid (GA) was chosen as the “green” reducing agent of graphene oxide (GO) to prepare the GA-functionalized GO (GGO). Then, the GGO nanosheets were introduced into the CNT network, and the GGO/CNT-PET composite films were successfully prepared by a simple spraying method. This type of transparent conductive film (TCF) possesses an excellent optoelectronic performance (Rs = 49.1 Ω/sq., T = ca. 80% at 550 nm) and a very low RMS roughness (approximately 6.89 nm). The sheet resistance of the films changed slightly after the 1000 bending cycles and 100 h of air exposure time, which indicated that the film has good mechanical properties and environmental stability. The composite TCFs were further applied to fabricate transparent film heaters (TFHs) and showed excellent Joule heating performance, fast response speed, good cycling stability, long-term stability, and controllable operating temperature (the power density of the TFHs shows an approximate linear behavior), which satisfy the requirements of TFHs in practical applications, such as safe voltage and temperature in wearable devices, the stable controlling temperature in smart windows, fast heating in defoggers, and so on.

Ultra‐Fast Wetting of the Fresh Popcorn

AbstractWithout chewing, the fresh popcorn dissolves immediately upon being put in the mouth. Such good taste decay dramatically with increasing the exposure time in air, especially in humid air. However, the involving mechanism of the saliva wetting the popcorn remains unclear. Here, it is revealed that the ultra‐fast wetting property of the fresh popcorn is the key for its good taste. For the fresh popcorn, the unique 3D throughout micro‐porous structure facilitates capillary flows both in‐plane and off‐plane at micro‐/nano‐ scale, and the water‐soluble crystalized starch further prompts the water spreading, which cooperatively leads to an immediate structural collapse. The unique ultra‐fast wetting of the fresh popcorn is therefore featured as the wetting with dissolving. After cooling down, the crystalized starch changes gradually into an insoluble amorphous state by absorbing water molecule, as is confirmed by the in situ XRD and infrared spectroscopy. As a result, the ultra‐fast wetting decays drastically with prolonging the in‐air exposure time, as well as the taste, which makes immediate cooking vital for the good taste. It is demonstrated that heating can partially restore the ultra‐fast wetting. It is envisioned that the result will inspire the innovative micro‐fabrication of various starch food by engineering the starch crystalline structure.

Control measure implications of COVID-19 infection in healthcare facilities reconsidered from human physiological and engineering aspects.

The Wells-Riley model invokes human physiological and engineering parameters to successfully treat airborne transmission of infectious diseases. Applications of this model would have high potentiality on evaluating policy actions and interventions intended to improve public safety efforts on preventing the spread of COVID-19 in an enclosed space. Here, we constructed the interaction relationships among basic reproduction number (R0) - exposure time - indoor population number by using the Wells-Riley model to provide a robust means to assist in planning containment efforts. We quantified SARS-CoV-2 changes in a case study of two Wuhan (Fangcang and Renmin) hospitals. We conducted similar approach to develop control measures in various hospital functional units by taking all accountable factors. We showed that inhalation rates of individuals proved crucial for influencing the transmissibility of SARS-CoV-2, followed by air supply rate and exposure time. We suggest a minimum air change per hour (ACH) of 7h-1 would be at least appropriate with current room volume requirements in healthcare buildings when indoor population number is < 10 and exposure time is < 1h with one infector and low activity levels being considered. However, higher ACH (> 16h-1) with optimal arranged-exposure time/people and high-efficiency air filters would be suggested if more infectors or higher activity levels are presented. Our models lay out a practical metric for evaluating the efficacy of control measures on COVID-19 infection in built environments. Our case studies further indicate that the Wells-Riley model provides a predictive and mechanistic basis for empirical COVID-19 impact reduction planning and gives a framework to treat highly transmissible but mechanically heterogeneous airborne SARS-CoV-2.