Ultraviolet germicidal irradiation: A prediction model to estimate UV-C-induced infectivity loss in single-strand RNA viruses.

Ultraviolet germicidal irradiation (UVGI) disinfection technology is effective in inactivating microorganisms. However, its performance can vary against different microorganisms due to their diverse structural and genomic features. Thus, rapid predictions of UV (254 nm) inactivation kinetics are essential, particularly for highly infectious emerging pathogens, such as SARS-CoV-2, during the extemporary COVID-19 pandemic. In this study, aiming at single-strand RNA (ssRNA) viruses, an improved genomic model was introduced to predict the UV inactivation kinetics of viral genomes using genome sequence data. First, the overall virus infectivity loss in an aqueous matrix was estimated as the sum of damage to both the entire genome and the protein capsid. Then, the "UV rate constant ratio of aerosol and liquid" was used to convert the UV rate constant for viruses in a liquid-based matrix to an airborne state. The prediction model underwent both quantitative and qualitative validation using experimental data from this study and the literature. Finally, with the goal of mitigating potential airborne transmission of ssRNA viruses in indoor environments, this paper summarizes existing in-duct UVGI system designs and evaluates their germicidal performance. The prediction model may serve as a preliminary tool to assess the effectiveness of a UVGI system for emerging or unculturable viruses or to estimate the required UV dose when designing such a system.

The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: A systematic review of filtration.

Historically, viruses have demonstrated airborne transmission. Emerging evidence suggests the novel coronavirus (SARS-CoV-2) that causes COVID-19 also spreads by airborne transmission. This is more likely in indoor environments, particularly with poor ventilation. In the context of airborne transmission, a vital mitigation strategy for the built environment is heating, ventilation, and air conditioning (HVAC) systems. HVAC features could modify virus transmission potential. A systematic review was conducted to identify and synthesize research examining the effectiveness of filters within HVAC systems in reducing virus transmission. A comprehensive search of OVID MEDLINE, Compendex, and Web of Science Core was conducted to January 2021. Two authors were involved in study selection, data extraction, and risk of bias assessments. Study characteristics and results were displayed in evidence tables and findings were synthesized narratively. Twenty-three relevant studies showed that: filtration was associated with decreased transmission; filters removed viruses from the air; increasing filter efficiency (efficiency of particle removal) was associated with decreased transmission, decreased infection risk, and increased viral filtration efficiency (efficiency of virus removal); increasing filter efficiency above MERV 13 was associated with limited benefit in further reduction of virus concentration and infection risk; and filters with the same efficiency rating from different companies showed variable performance. Adapting HVAC systems to mitigate virus transmission requires a multi-factorial approach and filtration is one factor offering demonstrated potential for decreased transmission. For filtration to be effective, proper installation is required. Of note, similarly rated filters from different companies may offer different virus reduction results. While increasing filtration efficiency (i.e., increasing MERV rating or moving from MERV to HEPA) is associated with virus mitigation, there are diminishing returns for filters rated MERV 13 or higher. Although costs increase with filtration efficiency, they are lower than the cost of ventilation options with the equivalent reduction in transmission. Systematic review registration: PROSPERO 2020 CRD42020193968.

The Impact of Heating, Ventilation, and Air-Conditioning Design Features on the Transmission of Viruses, Including SARS-CoV-2: Overview of Reviews.

BACKGROUND: The COVID-19 or SARS-CoV-2 outbreak was declared a pandemic by the World Health Organization in March 2020. Almost 2 years later (early February 2022), the World Health Organization reported over 383 million cases of the disease caused by the virus, with over 5.6 million deaths worldwide. Debate regarding the routes of transmission was substantial early in the pandemic; however, airborne transmission emerged as an important consideration. Infectious airborne agents can spread within the built environment through heating, ventilation, and air-conditioning (HVAC) systems. Multiple features of HVAC systems can influence transmission (eg, ventilation, filtration, UV radiation, and humidity). Understanding how HVAC features influence airborne transmission is critical to mitigate the spread of infectious agents. OBJECTIVE: Given the airborne transmission of SARS-CoV-2, an overview of reviews was conducted to understand what is already known from the scientific literature about how virus transmission may be affected by HVAC design features in the built environment. METHODS: Ovid MEDLINE and Compendex were searched from inception to January 2021. Two reviewers independently screened the titles, abstracts, and full text of potentially relevant reviews, using a priori inclusion criteria: systematic reviews examining the effects of HVAC design features on virus transmission. Two reviewers independently assessed the methodological quality using AMSTAR2. RESULTS: Searching identified 361 citations, of which 45 (12.5%) were potentially relevant and 7 (2%) were included. Reviews were published between 2007 and 2021 and included 47 virus studies. Two earlier reviews (2007 and 2016) of 21 studies found sufficient evidence that mechanical ventilation (airflow patterns and ventilation rates) plays a role in airborne transmission; however, both found insufficient evidence to quantify the minimum mechanical ventilation requirements. One review (2017) of 9 studies examining humidity and indoor air quality found that influenza virus survival was lowest between 40% and 80% relative humidity; the authors noted that ventilation rates were a confounding variable. Two reviews (2021) examined mitigation strategies for coronavirus transmission, finding that transmission decreased with increasing temperature and relative humidity. One review (2020) identified 14 studies examining coronavirus transmission in air-conditioning systems, finding that HVAC systems played a role in virus spread during previous coronavirus outbreaks. One review (2020) examined virus transmission interventions in public ground transportation, finding ventilation and filtration to be effective. CONCLUSIONS: Seven reviews synthesizing 47 studies demonstrated a role for HVAC in mitigating airborne virus transmission. Ventilation, humidity, temperature, and filtration can play a role in the viability and transmission of viruses, including coronaviruses. Recommendations for minimum standards were not possible owing to few studies investigating a given HVAC parameter. This overview examining HVAC design features and their effects on the airborne transmission of viruses serves as a starting point for future systematic reviews and identifying priorities for primary research.

The impact of heating, ventilation and air conditioning (HVAC) design features on the transmission of viruses, including the 2019 novel coronavirus (COVID-19): A systematic review of humidity.

The aerosol route has been a pathway for transmission of many viruses. Similarly, recent evidence has determined aerosol transmission for SARS-CoV-2 to be significant. Consequently, public health officials and professionals have sought data regarding the role of Heating, Ventilation, and Air Conditioning (HVAC) features as a means to mitigate transmission of viruses, particularly coronaviruses. Using international standards, a systematic review was conducted to comprehensively identify and synthesize research examining the effect of humidity on transmission of coronaviruses and influenza. The results from 24 relevant studies showed that: increasing from mid (40-60%) to high (>60%) relative humidity (RH) for SARS-CoV-2 was associated with decreased virus survival; although SARS-CoV-2 results appear consistent, coronaviruses do not all behave the same; increasing from low (<40%) to mid RH for influenza was associated with decreased persistence, infectivity, viability, and survival, however effects of increased humidity from mid to high for influenza were not consistent; and medium, temperature, and exposure time were associated with inconsistency in results for both coronaviruses and influenza. Adapting humidity to mitigate virus transmission is complex. When controlling humidity as an HVAC feature, practitioners should take into account virus type and temperature. Future research should also consider the impact of exposure time, temperature, and medium when designing experiments, while also working towards more standardized testing procedures. Clinical trial registration: PROSPERO 2020 CRD42020193968.

Filter evaluation and selection for heating, ventilation, and air conditioning systems during and beyond the COVID-19 pandemic.

Particle size removal efficiencies for 0.1-1.0 µm ( PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ ) and 0.3-1.0 µm ( PSE 0.3 - 1.0 $$ {PSE}_{0.3-1.0} $$ ) diameter of Minimum Efficiency Reporting Value (MERV) filters, an electrostatic enhanced air filter (EEAF), and their two-stage filtration systems were evaluated. Considering the most penetrating particle size was 0.1-0.4 µm particulate matter (PM), the PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ as an evaluation parameter deserves more attention during the COVID-19 pandemic, compared to the PSE 0.3 - 1.0 $$ {PSE}_{0.3-1.0} $$ . The MERV 13 filters were recommended for a single-stage filtration system because of their superior quality factor (QF) compared to MERV 6, MERV 8, MERV 11 filters, and the EEAF. Combined MERV 8 + MERV 11 filters have the highest QF compared to MERV 6 + MERV 11 filters and EEAF + MERV 11 filters; regarding 50% of PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ as the filtration requirements of two-stage filtration systems, the MERV 8 + MERV 11 filtration system can achieve this value at 1.0 m/s air velocity, while PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ values were lower than 50% at 1.5 m/s and 2.0 m/s. EEAF obtained a better PSE 0.3 - 1.0 $$ {PSE}_{0.3-1.0} $$ in the full-recirculated test rig than in the single-pass mode owing to active ionization effects when EEAF was charged by alternating current.

The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: A systematic review of ultraviolet radiation.

Respiratory viruses are capable of transmitting via an aerosol route. Emerging evidence suggests that SARS-CoV-2 which causes COVID-19 can be spread through airborne transmission, particularly in indoor environments with poor ventilation. Heating, ventilation, and air conditioning (HVAC) systems can play a role in mitigating airborne virus transmission. Ultraviolet germicidal irradiation (UVGI), a feature that can be incorporated into HVAC systems, can be used to impede the ability of viruses to replicate and infect a host. We conducted a systematic review of the scientific literature examining the effectiveness of HVAC design features in reducing virus transmission-here we report results for ultraviolet (UV) radiation. We followed international standards for conducting systematic reviews and developed an a priori protocol. We conducted a comprehensive search to January 2021 of published and grey literature using Ovid MEDLINE, Compendex, and Web of Science Core. Two reviewers were involved in study selection, data extraction, and risk of bias assessments. We presented study characteristics and results in evidence tables, and synthesized results across studies narratively. We identified 32 relevant studies published between 1936 and 2020. Research demonstrates that: viruses and bacteriophages are inactivated by UV radiation; increasing UV dose is associated with decreasing survival fraction of viruses and bacteriophages; increasing relative humidity is associated with decreasing susceptibility to UV radiation; UV dose and corresponding survival fraction are affected by airflow pattern, air changes per hour, and UV device location; and UV radiation is associated with decreased transmission in both animal and human studies. While UV radiation has been shown to be effective in inactivating viruses and reducing disease transmission, practical implementation of UVGI in HVAC systems needs to consider airflow patterns, air changes per hour, and UV device location. The majority of the scientific literature is comprised of experimental, laboratory-based studies. Further, a variety of viruses have been examined; however, there are few studies of coronaviruses and none to date of SARS-CoV-2. Future field studies of UVGI systems could address an existing research gap and provide important information on system performance in real-world situations, particularly in the context of the current COVID-19 pandemic. This comprehensive synthesis of the scientific evidence examining the impact of UV radiation on virus transmission can be used to guide implementation of systems to mitigate airborne spread and identify priorities for future research. Trial registration PROSPERO 2020 CRD42020193968.

Be alert for vapor intrusion of 1,4-dioxane from contaminated groundwater.

Vapor intrusion (VI) poses significant environmental problems that can degrade indoor air and pose human health risks. This study focuses on 1,4-dioxane, a widely-used volatile organic compound (VOC) that is found in groundwater, however, this compound has not received much attention in indoor air and measurement methods are not well developed. 1,4-dioxane is sufficiently volatile and highly mobile in groundwater, and thus can present a VI risk. In this study, we develop a sensitive analytical method for quantifying airborne 1,4-dioxane, provide a performance evaluation of the method, and initiate preliminary field measurements above a 1,4-dioxane groundwater plume. The method uses passive sampling, automated thermal desorption, and gas chromatography/mass spectroscopy. Numerous other VOCs can be simultaneously measured. A low detection limit (0.067 µg/m3) is attained, which allows quantification at concentrations below health-based guidelines. The performance evaluation suggests limits to sampling times in high humidity environments and other means to ensure good performance. The scenario analyses demonstrate potential impacts from shallow plumes, especially in flooded basements, and thus monitoring of 1,4-dioxane vapor intrusion in the flood season is an urgent need.

The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: A systematic review of ventilation and coronavirus.

Aerosol transmission has been a pathway for the spread of many viruses. Similarly, emerging evidence has determined aerosol transmission for Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) and the resulting COVID-19 pandemic to be significant. As such, data regarding the effect of Heating, Ventilation, and Air Conditioning (HVAC) features to control and mitigate virus transmission is essential. A systematic review was conducted to identify and comprehensively synthesize research examining the effectiveness of ventilation for mitigating transmission of coronaviruses. A comprehensive search was conducted in Ovid MEDLINE, Compendex, Web of Science Core to January 2021. Study selection, data extraction, and risk of bias assessments were performed by two authors. Evidence tables were developed and results were described narratively. Results from 32 relevant studies showed that: increased ventilation rate was associated with decreased transmission, transmission probability/risk, infection probability/risk, droplet persistence, virus concentration, and increased virus removal and virus particle removal efficiency; increased ventilation rate decreased risk at longer exposure times; some ventilation was better than no ventilation; airflow patterns affected transmission; ventilation feature (e.g., supply/exhaust, fans) placement influenced particle distribution. Few studies provided specific quantitative ventilation parameters suggesting a significant gap in current research. Adapting HVAC ventilation systems to mitigate virus transmission is not a one-solution-fits-all approach. Changing ventilation rate or using mixing ventilation is not always the only way to mitigate and control viruses. Practitioners need to consider occupancy, ventilation feature (supply/exhaust and fans) placement, and exposure time in conjunction with both ventilation rates and airflow patterns. Some recommendations based on quantitative data were made for specific scenarios (e.g., using air change rate of 9 h-1 for a hospital ward). Other recommendations included using or increasing ventilation, introducing fresh air, using maximum supply rates, avoiding poorly ventilated spaces, assessing fan placement and potentially increasing ventilation locations, and employing ventilation testing and air balancing checks. Trial registration: PROSPERO 2020 CRD42020193968.

Ultraviolet photocatalytic oxidation technology for indoor volatile organic compound removal: A critical review with particular focus on byproduct formation and modeling.

Photocatalytic oxidation (PCO)-based air filters are gaining attention owing to their capacity for indoor pollutant removal. This review summarized the application of ultraviolet-photocatalytic oxidation (UV-PCO) in heating, ventilation, and air conditioning (HVAC) systems, including the modeling studies, reactor designs, the influence of operational conditions, with emphasis on the common issue of byproduct generation, and the resulting indoor byproduct exposure levels. As a result, the concentrations of the typical byproducts for the most challenging pollutants were relatively low, except for the PCO of ethanol. Hence, UV-PCO is not recommended for buildings with high ethanol concentrations. Based on the formation of the formaldehyde, a new exposure-based evaluation standard for UV-PCO was developed to evaluate the feasibility of integrating UV-PCO reactors into an HVAC system. Then, applying the newly developed evaluation standard on a developed database (data size: 174) from the literature, 32.5% of the cases were identified as suitable for HVAC system applications in residential and commercial buildings, and all cases could be used for industrial buildings. Finally, a case study was conducted to develop a support vector machine (SVM) classification model with good accuracy, and challenging compound types, inlet concentrations, and air velocity were found to be the main parameters affecting the applicability of UV-PCO.

Ultraviolet germicidal irradiation (UVGI) for in-duct airborne bioaerosol disinfection: Review and analysis of design factors.

The rapid increase in global cases of COVID-19 illness and death requires the implementation of appropriate and efficient engineering controls to improve indoor air quality. This paper focuses on the use of the ultraviolet germicidal irradiation (UVGI) air purification technology in HVAC ducts, which is particularly applicable to buildings where fully shutting down air recirculation is not feasible. Given the poor understanding of the in-duct UVGI system regarding its working mechanisms, designs, and applications, this review has the following key research objectives:•Identifying the critical parameters for designing a UVGI system, including the characterization of lamp output, behavior of the target microbial UV dose-response, and evaluation of the inactivation performance and energy consumption.•Elucidating the effects of environmental factors (air velocity, air temperature, and humidity) on the UVGI system design parameters and optimization of the in-duct UVGI design.•Summarizing existing UVGI system designs in the literature and illustrating their germicidal and energy performance in light of COVID-19 mitigation.

Simulation and computer modeling of asphaltene in different solvents on oil-water interfaces using a molecular dynamic methodology.

Molecular dynamics (MD) simulations were used to study the thermodynamic properties of asphalt binder components, namely asphaltene, and other solvents, such as pentane or toluene, before and after adding pentane or toluene. The two systems were compared by MD simulation under lots of molecules, temperature and pressure to predict their internal energy, structure, and density as a function of time or distance between molecules. Then the simulation results of the two systems were analyzed and compared to determine the influence of different solvents on asphaltene aggregation behavior. The results show that the asphaltenes with pentane or toluene in the two systems have different structure and dynamic characteristics and will produce different precipitation and aggregation characteristics. The aggregation behavior of asphaltene at water - oil interface with or without pentane or toluene was studied. The relationship between the molecular structure and the aggregation of asphaltene in different solvents was investigated.

New modeling method to simulate asphaltenes at oil sands process in water management.

The study of various structures, physicochemical structures and dynamic characteristics of oil-water interface asphaltenes is an important basis for the large-scale development and efficient clean utilization of oil sands. The molecular dynamics simulations method provides a possibility for revealing the physicochemical structure and dynamic characteristics of oil sands. The emphasis of this paper is to study the physic-chemical structure of tar sands asphaltenes and the changes of their kinetic properties by using molecular dynamics simulations. Molecular dynamics was used to simulate the physicochemical and dynamic characteristics of asphaltenes in water treatment of the oil sands. In this research, the structural and dynamic properties of asphaltenes, such as density distribution, correlation (radial distribution function), root-mean-square deviation (RMSD), and mean azimuth shift (MSD), diffusion coefficient, the radius of gyration, volume viscosity and free energy in water treatment were systematically discussed. The simulation results of asphaltene at the oil-water interface revealed that, in the oil-water interface, oil and water will affect the solubility of asphaltene. The asphaltene molecules have different mobility and the ability to break molecular association, indicating that the structure and dynamic properties of asphaltene in the oil-water interface and the water-water interface are different.

VOC sources and exposures in nail salons: a pilot study in Michigan, USA.

PURPOSE: Exposures of nail salon technicians have received attention due to the potentially toxic materials used in nail products, which include volatile organic compounds (VOCs) such as formaldehyde and methyl methacrylate (MMA). This study characterized area and personal concentrations and other indoor air parameters in 17 nail salons in fall and winter seasons in three areas of Michigan. METHODS: VOC samples were analyzed using thermal desorption, gas chromatography and mass spectroscopy, and the VOC composition of 35 nail products (e.g., polish, top coat, base coat) was measured using headspace sampling. Ventilation rates were derived using CO2 concentrations, occupancy and building information, and VOC sources were apportioned by a novel application of chemical mass balance models. RESULTS: We detected ethyl acetate, propyl acetate, butyl acetate, MMA, n-heptane and toluene in most salons, and benzene, D-limonene, formaldehyde, and ethyl methacrylate in some salons. While MMA was not measured in the consumer and professional products, and the use of pure MMA in salons has been not been permitted since the 1970s, MMA was found in air at concentrations from 100 to 36,000 µg/m3 in 15 of 17 salons; thus its use appears to be commonplace in the industry. Personal measurements, representing exposures to workers and clients, were about twice those of the area measurements for many VOCs. CONCLUSION: This study identifies the products responsible for emissions, shows the widespread presence of MMA, and documents low ventilation rates in some salons. It also demonstrates that "informal" short-term sampling approaches can evaluate chemical exposures in nail salons, providing measurements that can be used to protect a potentially susceptible and vulnerable population. Additional controls, including restrictions on the VOC compositions and improved ventilation, can reduce exposures to salon workers and clients.

Volatile Organic Compounds (VOCs) in Conventional and High Performance School Buildings in the U.S.

Exposure to volatile organic compounds (VOCs) has been an indoor environmental quality (IEQ) concern in schools and other buildings for many years. Newer designs, construction practices and building materials for "green" buildings and the use of "environmentally friendly" products have the promise of lowering chemical exposure. This study examines VOCs and IEQ parameters in 144 classrooms in 37 conventional and high performance elementary schools in the U.S. with the objectives of providing a comprehensive analysis and updating the literature. Tested schools were built or renovated in the past 15 years, and included comparable numbers of conventional, Energy Star, and Leadership in Energy and Environmental Design (LEED)-certified buildings. Indoor and outdoor VOC samples were collected and analyzed by thermal desorption, gas chromatography and mass spectroscopy for 94 compounds. Aromatics, alkanes and terpenes were the major compound groups detected. Most VOCs had mean concentrations below 5 µg/m³, and most indoor/outdoor concentration ratios ranged from one to 10. For 16 VOCs, the within-school variance of concentrations exceeded that between schools and, overall, no major differences in VOC concentrations were found between conventional and high performance buildings. While VOC concentrations have declined from levels measured in earlier decades, opportunities remain to improve indoor air quality (IAQ) by limiting emissions from building-related sources and by increasing ventilation rates.

Experimental and modeling study of visible light responsive photocatalytic oxidation (PCO) materials for toluene degradation.

Only limited research has examined the development and application of visible light responsive photocatalytic oxidation (PCO), although such materials have great potential for mitigating concentrations of volatile organic compounds (VOCs) when applied to building surfaces. This study evaluates the performance and characteristics of a visible light responsive photocatalyst, specially, a co-alloyed TiNbON compound with a band energy of 2.3 eV. The PCO material was developed using urea-glass synthesis, characterized by scanning electron microscopy (SEM), diffuse reflectance spectra (DRS), powder X-ray diffraction (PXRD), and Brunauer-Emmett-Teller (BET) methods, and VOC removal efficiency was measured under visible light for toluene (1-5 ppm) at room temperature (21.5°C) and a range of relative humidity (RH: 25 to 65%), flow rate (0.78 to 7.84 cm/s), and irradiance (42 to 95 W/m2). A systematic parametric evaluation of kinetic parameters was conducted. In addition, we compared TiNbON with a commercial TiO2-based material under black light, estimated TiNbON's long-term durability and stability, and tested its ability to thermally regenerate. Using mass transfer and kinetic analysis, three different Langmuir-Hinshelwood (LH) type reaction rate expressions were proposed and evaluated. A LH model considering one active site and competitive sorption of toluene and water was superior to others. The visible-light driven catalyst was able to remove up to 58 % of the toluene, generated less formaldehyde than the commercial TiO2, could be fully regenerated at 150°C, and had reasonable durability and stability. This evaluation of TiNbON shows the potential to remove VOCs and improve air quality for indoor applications. Further research is needed to evaluate the potential for harmful by-products, to identify optimal conditions, and to use field tests to show real-world performance.

Performance of ultraviolet photocatalytic oxidation for indoor air applications: systematic experimental evaluation.

Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology.

Adsorption performance of titanium dioxide (TiO2) coated air filters for volatile organic compounds.

The photocatalytic oxidation (PCO) technology as an alternative method for air purification has been studied for decades and a variety of PCO models indicate that the adsorption of reactants on the catalyst surface is one of the major physical and chemical processes occurring at a heterogeneous photocatalytic reaction. However, limited study explored the adsorption effect of a photocatalyst. This study carried out a systematic evaluation of adsorption performance of titanium dioxide (TiO(2)) coated fiberglass fibers (FGFs), TiO(2) coated carbon cloth fibers (CCFs), and original CCFs air filters at various relative humidity conditions for nine volatile organic compounds. TiO(2)/FGFs, TiO(2)/CCFs, and CCFs were characterized by SEM for morphology and N(2) adsorption isotherm for BET surface area and pore structure. A bench-scale adsorption test setup was constructed and adsorption tests were performed at various relative humidity conditions and four different injected concentrations for each compound. The isothermal adsorption curves at low concentration levels were obtained and they were well described by Langmuir isotherm model. It was noticed that there were significant differences between the adsorption behaviors and photocatalytic activities of TiO(2)/FGFs and TiO(2)/CCFs. It was concluded that adsorption performance is closely related to the characteristics of substrates and therefore, the development of a substrate with high adsorption ability is a promising trend for improving the performance of the UV-PCO technology.