Laboratory Chamber Research Articles

Developing and Testing Standards to Assess Atmospheric Corrosion of Silver Witness Coupons

Silver witness coupons are used to assess the corrosivity and chemistry of an ambient environment. The formation of silver corrosion products such as silver chloride is highly dependent on local conditions. However, the mechanisms that are responsible for these corrosion products are not well-understood, and there is a lack of standards used to compare and assess the quality of observations.The goal of this study is to synthesize silver corrosion film standards with known thickness and morphology. Compounds of interest include silver chloride, silver oxide, silver sulfide, silver sulfite, and silver sulfate. These compounds were generated electrochemically by oxidizing the silver in the presence of the anion of interest (chloride, sulfite, or sulfate), chemically by submerging the silver in a solution containing the anion, and chemically by dipping the silver in molten silver salts. The surface chemistry of these films was then analyzed using galvanostatic reduction, x-ray diffraction, x-ray photon spectroscopy, Raman spectroscopy, and energy dispersion spectroscopy. The films generated from each method were compared against each other to determine the optimal film thickness and morphology. In the future, these results will be compared against the surface chemistry of silver films formed by testing in laboratory chambers or by exposure in field environments. Figure 1

Determination of personal exposure to volatile organic compounds and their health risks after the use of mosquito repellents in residential environments using passive sampling

The ubiquitous use of mosquito repellents in homes across Asia, Africa, and South America is related with human exposure to indoor volatile organic compounds (VOCs). There are three primary types of mosquito repellents: those in the form of coils, mats, and liquids. The repellent mechanisms of these products are distinct, resulting in the generation of varying types of VOCs during the repellent process. In this study, the emission characteristics of commercial coil-, mat-, and liquid-type mosquito repellents were observed in a laboratory chamber using real-time measurement. A previously developed personal passive sampler, ePTFE PS, was used to quantify personal exposure to indoor VOCs while 86 volunteers habitually used those three representative types for 3 h in their residence. Notable increase of indoor benzene was observed for coil- and mat-type mosquito repellents, while α-pinene concentration increased significantly following the use of liquid-type mosquito repellent. The average incremental cancer risks for benzene were 10−6 to 10−4 for adults following the use of coil- and mat-type mosquito repellents. The average non-cancer risks for all chemicals were <1 after the use of three types of mosquito repellents. Considering the potential human health risks associated with byproducts (e.g., particulate matter or carbon monoxide from incomplete combustion) emitted after mosquito coil use, further research on this topic is warranted.

Increase of the indoor concentration of volatile organic compounds after the use of incense and scented candle in studio apartments determined using passive sampling

Burning incenses and scented candles may provide harmful chemicals. Although many studies have evaluated volatile organic chemicals emitted by their use and related health risks, extension of our understanding for guiding appropriate use under various use conditions is necessary. In this study, emission characteristics of commercial incenses and scented candles were evaluated in a laboratory chamber using real-time measurement and the time-weighted average exposure concentrations of monoaromatic compounds and monoterpenes were assessed using passive samplers while volunteers living in a studio apartment use them. After burning incense, the average levels of benzene increased from 1.4 to 100 μg m−3. The presence of a wood core in commercial incense products was the main cause of high benzene emission by burning them although the increase in benzene was also influenced by factors such as the brand of the products, the number of incense sticks burned, the duration of each burning session, and ventilation period. Electrical warming of scented candles increased the levels of monoterpenes by factors of 16–30 on average. Considering the emission characteristics found in this study, exposure to benzene and monoterpenes could be mitigated by cautious use of those products in residential areas.

Influence of sand grain size on the nest escape of green sea turtle hatchlings

Sea turtle hatchlings rely on their finite energy reserve to sustain embryonic development in underground nests and during the first few days of their post-hatch life, including nest escape, beach crossing, and swimming offshore. This study aimed to investigate if the grain size of the nest substrate has an impact on green sea turtle (Chelonia mydas) hatchlings’ energy usage during nest escape. About-to-hatch green sea turtle eggs were incubated in laboratory chambers filled with either coarse-grain sand (φ = 0.507 phi) or fine-grain sand (φ = 2.028) at a temperature of 28oC. Open-flow respirometry was used to measure the hatchlings’ oxygen consumption rate during nest escape, which was then converted to energy consumption values. Results showed that hatchling morphology, hatching success, emergence success, and synchronous emergence rate were not significantly different between the groups of hatchlings in coarse versus fine sand. Hatchlings that dug through coarse sand emerged significantly faster (168 ± 13.9 h) than those in fine sand (233.21 ± 12.6 h) (t (26) = –3.473, p = 0.002). Additionally, the hatchlings in coarse sand (310.55 ± 28.1 kJ) consumed significantly less energy than hatchlings in fine sand (474.85 ± 64.7 kJ) (t (17.739) = –2.328, p = 0.032). A difference in amount of energy reserve upon emergence was detected between coarse and fine sand groups. To improve hatchery management practices, relocating “doomed” clutches into coarse sand (φ = 0.507) could potentially maximise the hatchlings’ energy reserve.

Method for early ignition detection based on the sampling dispersion of dangerous parameter

The object of the study is the selective dispersion of dangerous parameters of the gas environment during material fires. The practical importance of research consists in using the difference of sample dispersions of dangerous parameters of the gas environment on the intervals of absence and presence of ignition of materials for detection of ignition. The theoretical substantiation of the method of detecting fires in premises based on sample dispersions of current measurements of an arbitrary dangerous parameter of the gas environment, corresponding to the general populations of reliable absence and presence of fire, has been carried out. The method, at a given level of significance, determines the unbiased uniformly most powerful fire detection rule. This makes it possible to determine how much differences in sample variances are significant with a given level of significance and are caused by ignition or are random factors. Laboratory experiments were conducted to verify the proposed method. It was established that the influence of ignition on the value of the difference in the sample dispersion at the corresponding intervals of monitoring the carbon monoxide concentration, smoke density, and temperature of the gaseous environment of the laboratory chamber is different and depends on the type of ignition material. At the same time, the minimum difference of the sample dispersions is characteristic for observing the smoke density for all the studied materials. However, early detection of ignition of alcohol, paper, wood, and textiles when observing the smoke density is carried out when the threshold is exceeded by 9.01, 5.31, 2.13 and 2.55 times, respectively. It is shown that the method of early detection of fires, which is based on the detection of significant differences in sample dispersions of data from the relevant general populations

Predicting Floral Bud Progression for Three Peach Cultivars

The prediction of floral bud progression in commercial peach cultivars promotes knowledge about the adaptability of cultivars to the climatic conditions in a specific location under a climatic variability context. Phenology is relevant to improving the scheduling of cultural practices in peach orchards. This research aimed to predict the floral bud progression of three peach cultivars: ‘Harvester’, ‘Red Globe’, and ‘Rubyprince’. Floral bud progression was assessed using one-year-old shoots collected from an orchard located at the Chilton Research and Extension Center, Alabama. Samples were evaluated under laboratory and growth chamber conditions. We recorded the flower developmental stages daily to identify the transition among stages. Daily temperature records were used to estimate the heat requirement in terms of Growing Degree Days (GDD). After dormancy release, samples needed between 23 to 39 and 37 to 42 days to reach the petal fall stage for season 1 and season 2, respectively. In terms of heat requirements, cultivars needed between 425.5 to 721.5 and 684.5 to 777 GDD to end flowering. A logistic curve was adjusted to describe the growth of the different floral stages over time. The results are key to supporting peach growers in crop management practices such as orchard establishment, irrigation, fertilization, freeze and frost protection, and pollination under climate variability scenarios.

Bioaerosol size as a potential determinant of airborne E. coli viability under ultraviolet germicidal irradiation and ozone disinfection

Ultraviolet germicidal irradiation (UVGI) and ozone disinfection are crucial methods for mitigating the airborne transmission of pathogenic microorganisms in high-risk settings, particularly with the emergence of respiratory viral pathogens such as SARS-CoV-2 and avian influenza viruses. This study quantitatively investigates the influence of UVGI and ozone on the viability of E. coli in bioaerosols, with a particular focus on how E. coli viability depends on the size of the bioaerosols, a critical factor that determines deposition patterns within the human respiratory system and the evolution of bioaerosols in indoor environments. This study used a controlled small-scale laboratory chamber where E. coli suspensions were aerosolized and subjected to varying levels of UVGI and ozone levels throughout the exposure time (2–6 s). The normalized viability of E. coli was found to be significantly reduced by UVGI (60–240 μW s cm−2) as the exposure time increased from 2 to 6 s, and the most substantial reduction of E. coli normalized viability was observed when UVGI and ozone (65–131 ppb) were used in combination. We also found that UVGI reduced the normalized viability of E. coli in bioaerosols more significantly with smaller sizes (0.25–0.5 μm) than with larger sizes (0.5–2.5 μm). However, when combining UVGI and ozone, the normalized viability was higher for smaller particle sizes than for the larger ones. The findings provide insights into the development of effective UVGI disinfection engineering methods to control the spread of pathogenic microorganisms in high-risk environments. By understanding the influence of the viability of microorganisms in various bioaerosol sizes, we can optimize UVGI and ozone techniques to reduce the potential risk of airborne transmission of pathogens.

Organic aerosol formation from 222 nm germicidal light: ozone-initiated vs. non-ozone pathways.

Germicidal ultraviolet lamps outputting 222 nm light (GUV222) have the potential to reduce the airborne spread of disease through effective inactivation of pathogens, while remaining safe for direct human exposure. However, recent studies have identified these lamps as a source of ozone and other secondary pollutants such as secondary organic aerosol (SOA), and the health effects of these pollutants must be balanced against the benefits of pathogen inactivation. While ozone reactions are likely to account for much of this secondary indoor air pollution, 222 nm light may initiate additional non-ozone chemical processes, including the formation of other oxidants and direct photolytic reactions, which are not as well understood. This work examines the impacts of GUV222 on SOA formation and composition by comparing limonene oxidation under GUV222 and O3-only control conditions in a laboratory chamber. Differences between these experiments enable us to distinguish patterns in aerosol formation driven by ozone chemistry from those driven by other photolytic processes. These experiments also examine the influence of the addition of NO2 and nitrous acid (HONO), and investigate SOA formation in sampled outdoor air. SOA composition and yield vary only slightly with respect to GUV222vs. ozone-only conditions; NO2 and HONO photolysis do not appreciably affect the observed chemistry. In contrast, we observe consistent new particle formation under high-fluence 222 nm light (45 μW cm-2) that differs substantially from ozone-only experiments. This observed new particle formation represents an additional reason to keep GUV222 fluence rates to the lowest effective levels.

Understanding the active role of water in laboratory chamber studies of reactions of the OH radical with alcohols of atmospheric relevance.

In this work, we studied the reactions of three cyclic aliphatic alcohols with OH at room temperature, atmospheric pressure and different humidities in a Teflon reaction chamber. It was determined that the lower the solubility of the alcohol in water, the larger the effect of the humidity on the acceleration of the reaction. This experimental evidence allows suggesting that the acceleration is due to the reaction of the co-adsorbed reactants at the air-water interface of a thin water film deposited on the Teflon walls of the reaction chamber, instead of between co-reactants dissolved in the water film or due to gas phase catalysis as previously suggested. Therefore, formation of thin water films on different surfaces could have some implications on the tropospheric chemistry of these alcohols in the tropical regions of the planet with high humidity.

New energy-efficient materials for construction

Today in the world there is a huge amount of energy-efficient materials and products, including internal and external load-bearing and enclosing structures of buildings, which allow solving problems of energy saving in the operation of various buildings and structures. However, such materials do not always have high strength, as well as physical and mechanical properties for use in load-bearing parts of a large building. In this regard, the urgent tasks of developing energy-efficient structures and products are increasing strength, reducing thermal conductivity, increasing weather resistance and moisture resistance, as well as reducing cost.&#x0D; As a result of comprehensive research, the authors have developed new cellular concretes with high strength characteristics, low thermal conductivity and low cost based on local raw materials and waste. This approach leads to a significant reduction in energy and resource consumption and promotes the introduction of environmentally friendly production methods while maintaining high product quality standards.&#x0D; Experimental studies were carried out in a specially designed laboratory chamber. This installation ensured uniform temperature control inside the chamber, as well as uniform temperature distribution throughout the entire thickness of the products. This was achieved through a rational combination of energy sources used.&#x0D; The article presents the results of studies of the physical and mechanical properties of foam concrete and the structural features of the material. The production of high-quality products became possible thanks to a combination of mild heat treatment conditions and the exothermic properties of cement. In addition, the impact of additional electrical energy at a minimum consumption (10-20 kWh/m3) on the hardening process of foam concrete is characterized by a periodic and short-term effect. In contrast, traditional heat treatment methods require significantly higher energy consumption - from 80 to 100 kWh/m3.&#x0D; The results of X-ray and electron microscopy studies confirmed that the developed energy-efficient materials have high physical and mechanical properties and low cost.

Features of the coefficient of variation of parameters of the gas environment in fire in the premises

The object of the study is the selective coefficient of variation of dangerous parameters of the gas environment during the ignition of materials. The measure of the sample coefficient of variation of an arbitrary hazardous parameter of the gas environment observed at an arbitrary time interval is substantiated. The representativeness error of the measure of the sampling coefficient of variation, which depends on the value of the measure and the sample size, was determined. The measure allows you to numerically determine its value for an arbitrary observation interval. The difference in the measure at the intervals corresponding to the reliable absence and occurrence of ignition allows to detect the occurrence of ignition of the material. According to the results of laboratory studies, the measures of the sample coefficient of variation for carbon monoxide concentration, smoke density, and temperature of the gas medium in the laboratory chamber at intervals of absence and appearance of ignition of alcohol, paper, wood, and textiles were determined. It was established that the dangerous parameters of the gas environment at the intervals of absence and presence of ignition are characterized by different values of the increase in the measure of the sample coefficient of variation. For example, it is determined that the ignition of alcohol causes the maximum increase in the measure for carbon monoxide concentration from 0.135 to 0.441, for smoke density from 0.629 to 0.805, and for temperature from 0.001 to 0.115. When paper catches fire, the measure for carbon monoxide concentration and temperature increases from 0.0026 to 0.140 and from 0.0019 to 0.05, respectively. When burning wood, the measure for carbon monoxide concentration and temperature increases from 0.0072 to 0.177 and from 0.0067 to 0.016, respectively. The obtained results, provided that the hazardous parameters of the gas environment in the premises are measured and the sample coefficient of variation is calculated in practice, make it possible to use them in the creation of early fire detection systems

Optimization of electrical resistivity survey utilizing modified harmony search algorithm to predict anomalous zone ahead of tunnel faces

Predicting anomalies ahead of a tunnel face is essential to ensure construction safety and efficiency during tunneling. This study proposes an optimization system to estimate the characteristics of anomalies ahead of a tunnel face. The developed system can estimate the location, the thickness and the electrical resistivity of the anomaly using inverse analysis based on the modified harmony search algorithm with resistivity measurement. To verify the efficacy of the developed system, laboratory chamber tests were conducted by simulating ground formations with faults. The experimental results indicated that the developed system had substantial prediction performance with a short data analysis time. Notably, the location of an anomaly was relatively well predicted compared to the other properties, which is crucial information that can prevent potential risks. Therefore, the system could predict anomaly characteristics and enable the appropriate management of potential risks.

Formation of Highly Oxidized Organic Compounds and Secondary Organic Aerosol from α-Thujene Ozonolysis.

We conducted laboratory chamber experiments to probe the gas- and particle-phase composition of oxidized organics and secondary organic aerosol (SOA) formed from α-thujene ozonolysis under different chemical regimes. The formation of low-volatility compounds was observed using chemical ionization mass spectrometry with nitrate (NO3-) and iodide (I-) reagent ions. The contribution of measured low-volatility compounds to particle growth was predicted using a simple condensational growth model and found to underpredict the measured growth rates in our chamber (on the order of several nm min-1). The yields of low-volatility compounds and SOA mass were similar to those of other monoterpene ozonolysis systems. While semivolatile compounds C10H14-16O3-7 were measured most abundantly with I- reagent ion, a large fraction of products measured with NO3- were C5-7 fragments with predicted intermediate volatility. Additionally, particle composition was measured with ultrahigh-performance liquid chromatography with high-resolution mass spectrometry and compared to particle composition from α-pinene ozonolysis. Structural isomers were identified from tandem mass spectrometry analysis of two abundant product ions (C8H13O5-, C19H27O7-). Our results indicate that although this system efficiently generates low-volatility organics and SOA under the conditions studied, fragmentation pathways that produce more highly volatile products effectively compete with these processes.

The Effects of Constant Illuminance at Multiple Temperatures Towards Muscle Activities for Rubber Scrap Industries

The objective of this study is to determine the effect of ergonomic factors, such as temperature and illuminance level towards muscle activities through repetitive loading and unloading tasks. The study settings are in Ergonomic Laboratory Chamber and a rubber factory. Six male respondents that participated in this study wear Electromyography (EMG) device on both sides of their bodies to measure muscle fatigue. EMG output signal data were analysed to determine the correlation between muscle activities with illuminance level and temperature. At constant 500 lux illuminance level and 24˚C temperature, respondent’s body shows optimum correlation between left sides and right sides. On the contrary, findings show unbalanced correlation at 19˚C and 32˚C which indicate one side of the body is using too much energy for the task.

Revealing the peculiarities of asymmetry and kurtosis coefficients of gas medium parameters in premises during fire

The object of the study is the coefficients of asymmetry and excess of the selective distribution of hazardous parameters of the gas environment during material fires. The practical importance of the research lies in the use of measures of asymmetry and kurtosis for early detection of fires. The measures of asymmetry and kurtosis for sampling the final size of an arbitrary dangerous parameter of the gas environment are substantiated. The proposed measures make it possible to investigate the peculiarities of the coefficients of asymmetry and kurtosis in relation to the selective distribution of an arbitrary dangerous parameter of the gas environment. At the same time, it becomes possible to numerically determine the degree of difference of the sample distributions of dangerous parameters from the Gaussian, as well as the features of such measures. Experiments were conducted to determine the degree of asymmetry and excess of dangerous parameters of the gas environment in the laboratory chamber at the intervals of the absence and presence of ignition of the test materials. The obtained results indicate that on the intervals of absence and presence of fires, the selective distributions of dangerous parameters of the gas environment differ from the Gaussian distribution. Distributions are complex and individual in nature. Features of measures of asymmetry and kurtosis depend on the type of ignition material. It was established that the maximum values of the modulus of increase in the degree of asymmetry are characteristic for the carbon monoxide concentration (2.939) during the ignition of paper, for the smoke density (3.098) during the ignition of textiles, as well as for the temperature during the ignition of alcohol (7.163) and wood (1.06). It was determined that the maximum values of the modulus of excess measure increase are characteristic for smoke density (4.678) when paper, wood (1.652) and textiles (28.932) ignite, as well as for temperature (49.377) when alcohol ignites

A Coupled Volatility and Molecular Composition Based Source Apportionment of Atmospheric Organic Aerosol

We apply non-negative matrix factorization (NNMF) to molecular composition and volatility measurements of ambient sub-micrometer particles made using a high-resolution time of flight chemical ionization mass spectrometer (HRToF-CIMS) equipped with a custom filter inlet for gases and aerosols (FIGAERO) as part of the Southern Oxidant and Aerosol Study (SOAS). The resulting factors have a representative thermogram, which carries information on the factor volatility and unique weights for individual ions corresponding to molecular components of measured organic aerosol (OA). These properties and the diurnal patterns of factor weights are used to assign a specific source to each factor. With no a priori information used as input, the routine produces a set of factors with spectra that align well with those previously determined from several laboratory chamber experiments. The factorization routine gains relevance and separation of OA composition when using resolved thermograms as input rather than integrated thermogram time series. Of the seven factors produced by NNMF using the thermogram data, three are attributed to monoterpene-derived OA with extremely low, low, and semivolatile volatility. These three factors together represent 68% of the total organic aerosol mass examined, consistent with previous studies using a spectral basis set. Additionally, two factors were sourced to isoprene chemistry, one representing IEPOX-derived SOA, and the other relating to other oxidation products exhibiting relatively low volatility. The two isoprene-related factors account for 22% of OA mass. Notably absent is a category exclusively capturing the behavior of particulate organic nitrates (PON), which may be consistent with the relatively low local concentrations of PON observed and points to limitations of factorization to fully characterize OA. However, NNMF applied to the volatility and molecular level information from the FIGAERO HRToF-CIMS can resolve dominant precursors and chemical properties of ambient OA components with minimal assumptions.

Comparison of bicoherence on the ensemble of realizations and a selective evaluation of the bispectrum of the dynamics of dangerous parameters of the gas medium during fire

The object of the study is the bicoherence of the bispectrum assessment of the dynamics of dangerous parameters of the gas environment during the ignition of materials. The subject is a measure of bicoherence of the bispectrum estimation from the ensemble of realizations and selective bispectrum estimation for the dynamics of hazardous parameters of the gas environment. The practical importance of the research is the use of the measure of bicoherence of the bispectrum for the early detection of fires. The measure of bicoherence of the dynamics of hazardous parameters of the gas environment is substantiated, which allows them to be numerically compared for the studied bispectrum estimates. As such measure, it is proposed to use the integral value of bicoherence for a given frequency interval, which makes it possible to numerically compare the bicoherence of bispectrum estimates for arbitrary time intervals of the dynamics of hazardous parameters of the gas environment. On the basis of the proposed measure for the frequency range of 0.2–2 Hz, a comparison of the integral bicoherence of the bispectrum estimates was made. The numerical value of the measure was determined for three fixed time intervals of the dynamics of hazardous parameters of the environment, corresponding to the absence of ignition, the occurrence of ignition, and the subsequent burning of test materials in the laboratory chamber. According to the results of the comparison of such values, it was established that the bicoherence of the bispectrum estimation from the ensemble of realizations is the most appropriate for detecting fires. When ignited, the numerical value of the measure for all test materials is about 90°. This means that the nature of the dynamics of hazardous environmental parameters in the event of fires becomes random. In this regard, the proposed measure is recommended to be used as a test for early detection of fires.

A Scheme for Representing Aromatic Secondary Organic Aerosols in Chemical Transport Models: Application to Source Attribution of Organic Aerosols Over South Korea During the KORUS‐AQ Campaign

AbstractWe present a new volatility basis set (VBS) representation of aromatic secondary organic aerosol (SOA) for atmospheric chemistry models by fitting a statistical oxidation model with aerosol microphysics (SOM‐TOMAS) to results from laboratory chamber experiments. The resulting SOM‐VBS scheme also including previous work on SOA formation from semi‐ and intermediate volatile organic compounds (S/IVOCs) is implemented in the GEOS‐Chem chemical transport model and applied to simulation of observations from the Korea‐United States Air Quality Study (KORUS‐AQ) field campaign over South Korea in May–June 2016. Our SOM‐VBS scheme can simulate the KORUS‐AQ organic aerosol (OA) observations from aircraft and surface sites better than the default schemes used in GEOS‐Chem including for vertical profiles, diurnal cycle, and partitioning between hydrocarbon‐like OA and oxidized OA. Our results confirm the important contributions of oxidized primary OA and aromatic SOA found in previous analyses of the KORUS‐AQ data and further show a large contribution from S/IVOCs. Model source attribution of OA in surface air over South Korea indicates one third from domestic anthropogenic emissions, with a large contribution from toluene and xylenes, one third from external anthropogenic emissions, and one third from natural emissions.

Field and laboratory evaluation of PurpleAir low-cost aerosol sensors in monitoring indoor airborne particles

Due to the adverse health effects of residential air contaminants, there have been increased efforts to monitor indoor particulate matter (PM) concentration using low-cost sensors. However, little information is available about the performance of low-cost sensors in monitoring indoor aerosols. We established a research framework to examine the performance of a widely used low-cost sensor in the U.S. (PurpleAir) along with two research-grade light scattering sensors (Grimm 11-A, Sidepak AM520) in a laboratory chamber and a full-scale residential testbed. The results show that low-cost sensors can yield relatively high intra-model consistency for mass concentrations; however, the consistency is lower when measuring particles >1 μm than research-grade sensors. Regression analysis with research-grade sensors shows higher linearity for mass concentration than number concentration. These trends of mass and number concentrations are likely attributed to the size selectivity of Plantower PMS5003 sensor in PurpleAir that constrains the number fractions of specific particle size bins. The results also show that concentration discrepancy between the low-cost sensor and research-grade sensor increases as indoor mass concentration increases, suggesting that sensor quality assurance is needed for episodic indoor emission events that lead to elevated PM2.5 concentrations (>100 μg m−3).

Evaluation of human walking-induced resuspension of bacteria on different flooring materials

Walking and other human activities resuspend deposited pathogens from surfaces into the air, potentially leading to infection through inhaling the bioaerosols. We performed experiments in a laboratory chamber to quantify the pathogen resuspension from a human stepping on pathogen-seeded flooring. Three common flooring materials were chosen: carpet, vinyl tile, and hard wood. Three different types of bacteria were tested: Escherichia coli, Pseudomonas alcaligenes, and Staphylococcus epidermidis. The bacteria were first aerosolized into an experimental chamber and allowed to deposit onto the clean flooring materials, followed by a single human step on the flooring performed to resuspend the bacteria. The result showed that the resuspension emission factor (normalized parameter for the ratio of resuspended mass in the air to the mass available for resuspension on the surface during a resuspension event) of tested bacteria ranged from 3.4 × 10−5 to 2.1 × 10−4. For this study, because the resuspension mechanism is one footstep, the resuspension emission factor is also equivalent to the resuspension fraction (fraction of settled particles resuspended per footstep). The carpet consistently resulted in the highest emission factor of biological material resuspended from the surface to the air. In addition, the resuspension emission factor for Gram positive, S. epidermidis, was higher than that of the other two Gram negative bacteria for all floorings. The findings from this study provide valuable estimates for the emission of biological particles by resuspension and comparison to non-biological particles for estimating the risk of pathogen exposure in occupied environments.