Hazardous Air Pollutants Research Articles

Optimization of effecting parameters for flue gas desulfurization in a self‐priming venturi scrubber using response surface methodology

AbstractHydrogen sulfide (H2S), a highly poisonous and corrosive gas, is regarded as a hazardous air pollutant with significant effects on human health. Hence, reduction of hydrogen sulfide (H2S) gas from the atmosphere is very essential. In the present work, self‐priming venturi scrubber is employed to extract H2S gas from the air. Response surface methodology (RSM) with a central composite design (CCD) has been selected to investigate maximizing the H2S removal efficiency by optimizing the process variables. Experiments were carried out by altering the throat gas velocity, outer cylinder liquid level and inlet concentration of H2S. The analysis of variance (ANOVA) test showed that the parameters had a significant effect on the efficiency of H2S removal. A quadratic equation has been developed that accurately predicts the percentage of removal efficiency. The appropriateness of the generated model has been verified by the value of higher R2 resulting from the regression analysis. According to the observations, the velocity of throat gas has the highest effect on the H2S removal efficiency, whereas inlet H2S concentration has the least effect.

Enhancing Benzene Combustion Activity through Preferential Platinum Atom Exposure via Strategic Pt-Cu Alloying.

Volatile organic compounds such as benzene are hazardous air pollutants that require effective elimination. Noble metal-based catalysts exhibit high benzene combustion activity, but their prohibitive cost necessitates strategies to enhance utilization efficiency. This study investigates a Pt-Cu alloy catalyst for improved benzene combustion by preferentially exposing Pt active sites through Cu alloying. Aberration-corrected scanning transmission electron microscopy and X-ray spectroscopy characterize the nanoscale distribution and enrichment of Pt on the alloy surface. Kinetic measurements demonstrate substantially enhanced activity compared with Pt catalysts, attributed to increased Pt metallic site exposure rather than alteration of the reaction mechanism. In situ Fourier transform infrared (FTIR) spectroscopy reveals a higher abundance of terrace-like Pt sites in the alloy, beneficial for benzene adsorption. Partial pressure dependence analyses indicate competitive adsorption of benzene and O2, following Langmuir-Hinshelwood kinetics. These findings provide conceptual insights into tuning surface composition in bimetallic catalysts to optimize noble metal efficiency, with broad applicability for sustainable catalytic process advancement.

Portable, low-cost samplers for distributed sampling of atmospheric gases

Abstract. Volatile organic compounds (VOCs) contribute to air pollution both directly, as hazardous gases, and through their reactions with common atmospheric oxidants to produce ozone, particulate matter, and other hazardous air pollutants. There are enormous ranges of structures and reaction rates among VOCs, and there is consequently a need to accurately characterize the spatial and temporal distribution of individual identified compounds. Current VOC measurements are often made with complex, expensive instrumentation that provides high chemical detail but is limited in its portability and requires high expense (e.g., mobile labs) for spatially resolved measurements. Alternatively, periodic collection of samples on cartridges is inexpensive but demands significant operator interaction that can limit possibilities for time-resolved measurements or distributed measurements across a spatial area. Thus, there is a need for simple, portable devices that can sample with limited operator presence to enable temporally and/or spatially resolved measurements. In this work, we describe new portable and programmable VOC samplers that enable simultaneous collection of samples across a spatially distributed network, validate their reproducibility, and demonstrate their utility. Validation experiments confirmed high precision between samplers as well as the ability of miniature ozone scrubbers to preserve reactive analytes collected on commercially available adsorbent gas sampling cartridges, supporting simultaneous field deployment across multiple locations. In indoor environments, 24 h integrated samples demonstrate observable day-to-day variability, as well as variability across very short spatial scales (meters). The utility of the samplers was further demonstrated by locating outdoor point sources of analytes through the development of a new mapping approach that employs a group of the portable samplers and back-projection techniques to assess a sampling area with higher resolution than stationary sampling. As with all gas sampling, the limits of detection depend on sampling times and the properties of sorbents and analytes. The limit of detection of the analytical system used in this work is on the order of nanograms, corresponding to mixing ratios of 1–10 pptv after 1 h of sampling at the programmable flow rate of 50–250 sccm enabled by the developed system. The portable VOC samplers described and validated here provide a simple, low-cost sampling solution for spatially and/or temporally variable measurements of any organic gases that are collectable on currently available sampling media.

Biofiltration of Volatile organic compounds Using Chir Pine Cone Nuts Inoculated with Pseudomonas putida

Volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) are the major pollutants in industrial and agricultural emissions. This study targets the efficiency and applicability of biofiltration to remove methanol and n-hexane, two common air pollutants, using Chir pine cone nuts as filter media and Pseudomonas putida as the inoculant. The designed biofilter was operated between 25-35°C, with an airflow rate of 0.35 m3 h-1 and nutrient supply of 1-2 L Day-1. From a 60-day operating period, methanol's removal efficiency was higher than n-hexane, with a maximum removal efficiency of 93.91% achieved at an inlet loading rate of 101.39 g m-3h-1 for methanol and 87.96% at 398.46 g m-3h-1 for n-hexane. The effects of varying loading rates on the elimination capacity for both pollutants were also studied. In addition, the temperature profile of the biofilter, microbial analysis, and the BOD concentration of leachate was also studied during the operation period. The findings offer insights into the potential use of Chir pine nuts as filter media for the biodegradation of methanol and n-hexane and provide a foundation for future research to optimize the biofilter system's design and operation to increase its removal efficiency of other contaminants.

Reduce production or increase efficiency? Hazardous air pollutants regulation, energy use, and the synergistic effect on industrial enterprises' carbon emission

Theoretically, the synergistic reduction strategy aimed at curbing both carbon and air pollutants emissions is more cost-effective than a singular emission abatement approach. Using a firm-level panel dataset, we employ the difference-in-differences (DID) method to estimate the impact of hazardous air pollutant regulation on carbon and air pollutants emissions in China. We found that the hazardous air pollutant regulation led to a decrease in firm-level carbon emissions and sulfur dioxide (SO2) emissions of 5% and 10%, respectively. Mechanism analysis shows that source reduction is the key for firms to achieve synergistic emission reductions. Furthermore, firms' source reduction strategies lie in improving energy efficiency, rather than reducing output. Environmental policy instruments should be based on a more synergistic approach.

Effect of the Method Detection Limit on the Health Risk Assessment of Ambient Hazardous Air Pollutants in an Urban Industrial Complex Area

Hazardous air pollutants (HAPs) significantly impacted environmental air quality and were widely studied to determine human health risks. Kaohsiung is Taiwan’s second-largest city, known for its heavily industrialized and densely populated development. The Linhai industrial park, located in this region, contains roughly 500 industrial facilities that contributed to the emission of HAPs. The purpose of this study was to identify the volatile organic compound (VOCs) and particulate matter (PM)-bounded heavy metals and to examine the effects of the method detection limit (MDL) for analyzed species and the sampling program on health risk assessments. This study identified formaldehyde, 1,2-dichloroethane, acetaldehyde, benzene, and vinyl chloride. As, ethylbenzene, Ni, Cr(VI), Cd, Pb, and 1,3-butadiene were defined as high-risk species and VOCs accounted for more than 95% of respiratory-related health risks, this study proposes that the MDL for analysis methods and the sampling frequency for different species (and the species of interest) would eventually affect the results of health risk assessments. In other words, the current control strategies for reducing health risks may be ineffective. This research output can be used to comprehend the effects of MDL on the health risk assessments of HAPs better while also providing a reliable method to determine the major sources of air pollutants in urban industrial areas.

Removal of incense smoke and corollary particulate matter using a portable bipolar air ionizer in an unventilated setup

Introduction: Indoor air pollution-associated health risk is substantially higher than outdoor. Incense smoke represents a group of multiple hazardous air pollutants including particulate matter. Bipolar air ionizers have been one of the most escalated indoor air cleaning options in recent years. Albeit, removal efficiency against incense smoke and potential byproduct ozone have been little understood due to limited studies.Method: The present study assessed a portable needlepoint technology-based bipolar air ionizer’s removal efficacy against incense smoke in unventilated glass boxes (size 0.16 m3). A series of experiments were performed in order to estimate the average efficiency. The total removal efficacy of bipolar air ionizer (BAI eff.) was estimated by using empirical equations of the particulate matter PM2.5 (BAI eff. pm2.5) and PM10 removal (BAI eff.pm10). Particulate matter was used as the marker of incense smoke in this study. The concentration of particulate matter, potential byproduct ozone, relative humidity, and the temperature was monitored by a customized sensor-based air quality monitor.Results: The tested bipolar air ionizer showed a significant decline in incense smoke. The average reduction in PM2.5 and PM10 concentration was observed by 74%–75%. The overall efficacy (BAI eff) against incense smoke particulate proportion was 90% ± 10% compared to the control. Byproduct ozone was not exceeded abnormally. However, the marginal elevation in temperature and humidity (up to 5°C or 21%) and humidity (1.8%) were observed when the bipolar air ionizer was conducted.Discussion: Incense smoke consists of multiple hazardous air pollutants including volatile organic compounds and carcinogens. Incense smoke may be the major source of household pollution. A portable bipolar air ionizer could be an auxiliary air cleaning option where incense burning practices are common.

Effect of Ozone Stresses on Growth and Secondary Plant Metabolism of Brassica campestris L. ssp. chinensis

Determining plant responses to hazardous air pollutants is critical in predicting food security programs and challenges in the future. This study aimed to determine the effects of various ozone levels on plant growth responses (leaf area, dry matter, and number of leaves) and biochemical quality (photopigments and glucosinolates) on Brassica campestris L. ssp. chinensis (Pak-Choi). The experiment was conducted within test chambers under different ozone concentrations (60, 150, and 240 ppb for 2 h/day). Leaf area and dry matter were negatively correlated with increasing ozone concentrations, but the number of leaves was not affected by ozone treatment. Lycopene and chlorophylls also showed the same tendency. Even if the ambient ozone concentration was only elevated for a short time, various glucosnilates (GLS) have been diversely affected. The total aliphatic GLS content was reduced. In contrast, the total indole GLS increased at the highest ozone concentration, and the aromatic GLS significantly increased and then decreased as the ozone concentration level increased. These results provide evidence of the strong effect of ozone stress on the plant quality of Pak-Choi with respect to certain secondary plant metabolites. These findings provide an understanding of elevated ozone effects in urban horticulture sites on the growth and metabolite profiling of Brassica plants.

Characterization of the sources and health risks of polycyclic aromatic hydrocarbons in PM2.5 and their relationship with black carbon: A case study in northern Taiwan

Polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) often coexist in PM2.5 because both form during the incomplete combustion of organic matter. These compounds are regarded as hazardous air pollutants with potential health effects, including respiratory and cardiovascular effects. In this study, to evaluate the health risks of PAHs and BC at an urban site in northern Taiwan, 16 priority PAHs and BC, identified by the United States Environmental Protection Agency, were analyzed and quantified in PM2.5 to determine their concentrations, their relationship with each other, and their likely sources. The results indicated that the mean concentrations of total PAHs and BC were 0.91 ng m−3 and 0.97 μg m−3, respectively, with a significant positive correlation between them, indicating the same emission sources. The results also indicated that fossil fuel combustion and traffic emissions were primary contributors to PAHs, with wood and biomass combustion playing a less prominent role. Among these 16 priority PAHs, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[b]fluoranthene, and indeno[1,2,3-cd]pyrene served as major carcinogenic compounds, accounting for 89.0% of the total carcinogenic toxicity. Thus, the lifetime excess cancer risk resulting from PAH exposure was estimated as 8.03 × 10−6, indicating a potential carcinogenic risk to human health at the sampling site. Overall, this study highlights the need for future mitigation policies for traffic emissions and fossil fuel combustion for reducing the local emissions of BC and co-produced PAHs in northern Taiwan.

Development and demonstration of a data visualization platform of short-term guidelines for ambient air levels of benzene during disaster response in Houston, Texas.

Industrial disasters have caused hazardous air pollution and public health impacts. Response officials have developed limited exposure guidelines to direct them during the event; often, guidelines are outdated and may not represent relevant elevated-exposure periods. The 2019 Intercontinental Terminals Company (ITC) fire in Houston, Texas led to large-scale releases of benzene and presented a public health threat. This incident highlights the need for effective response and nimble, rapid public health communication. We developed a data-driven visualization tool to store, display, and interpret ambient benzene concentrations to assist health officials during environmental emergencies. Guidance values to interpret risk from acute exposure to benzene were updated using recent literature that also considers exposure periodicity. The visualization platform can process data from different sampling instruments and air monitors automatically, and displays information publicly in real time, along with the associated risk information and action recommendations. The protocol was validated by applying it retrospectively to the ITC event. The new guidance values are 6-30 times lower than those derived by the Texas regulatory agency. Fixed-site monitoring data, assessed using the protocol and revised thresholds, indicated that eight shelter-in-place and 17 air-quality alerts may have been considered. At least one of these shelter-in-place alerts corresponded to prolonged, elevated benzene concentrations (~1000 ppb). This new tool addresses essential gaps in the timely communication of air pollution measurements, provides context to understand potential health risks from exposure to benzene, and provides a clear protocol for local officials in responding to industrial air releases of benzene. Integr Environ Assess Manag 2024;20:533-546. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Correspondence on "Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California".

Correspondence on "Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California".

Rebuttal to Correspondence on "Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California".

Rebuttal to Correspondence on "Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California".

Extending Multi-Pathway Human Health Risk Assessment from Regional to Country-Wide—A Case Study on Kuwait

Air pollution has emerged as a pressing global issue in recent decades. While criteria pollutants and greenhouse gases contribute to the problem, this article explicitly addresses hazardous air pollutants (HAPs). This work estimates the country-wide cumulative human health impacts from exposure to HAPs. Kuwait is used as the case study due to data availability and non-fragmentation of data. At present, the evaluation of multi-pathway human health risks arising from exposure to HAPs is incomplete, as indirect pathways have not been considered. Furthermore, only a few HAPs, such as benzene, have established ambient air quality standards specifically intended to safeguard human health, leaving many HAPs unregulated. This study considers several pathways (both direct and indirect) and various environmental media (air, water, plants, soil, and animal tissue). The findings indicate that cumulative health risks in the coastal air quality zone are within acceptable limits but are notably higher when compared to the other air quality zones. For cancer risks, only the Ahmadi Hospital, with a cancer risk of 1.09 × 10−5 for the resident adult exposure scenario, slightly exceeds the acceptable risk level of 1 × 10−5. The proposed methodology integrates the results from a country-wide emissions inventory composed of different air quality zones, air dispersion and deposition modeling, multi-pathway transport-and-fate analysis, exposure quantification, and health risk and hazard characterization. It also extends and adapts EPA methodologies initially designed for hazardous waste combustion facilities to additional emission sources and provides a case study for a region seldom subjected to such human health risk assessments.

Bithiophene-naphthalene chalcone as a fluorescent pigment in eco-friendly security ink formulation

Approaches to prevent document/product forgery using eco-friendly printing inks and security printing techniques on flexible substrates are two vital areas of research that demand coherent advancements. In this context, a new bithiophene-naphthalene chalcone (BTNP) was synthesized and characterized as a fluorescent pigment for use in security ink. BTNP exhibited good solid-state and solution phase fluorescence with intramolecular charge transfer confirmed using theoretical studies and emission spectra collected in THF/THF–hexane mixtures. The aggregation-induced emission of BTNP was established using solution phase studies in THF/THF–water mixtures. The strong solid-state yellow emission of BTNP prompted its use as a pigment in the preparation of an environment-friendly UV fluorescent formulation, devoid of any volatile organic compounds or hazardous air pollutants. The screen prints obtained on a UV dull paper substrate utilizing BTNP ink revealed good fluorescence, photostability, colorimetric, densitometric, and rub resistance characteristics, which showcase the potential applicability of the BTNP formulation in security printing. The low cytotoxic nature of the chalcone as observed in the MTT assay could also be exploited for the use of formulation in inkpads.Graphical abstract

Optimal location and performance prediction of portable air cleaner in composite room shapes using convolutional neural network

Portable air cleaners are commonly used to eliminate hazardous indoor air pollutants such as particulate matters and infectious viruses. The effectiveness of portable air cleaners heavily relies on their installation location, which affects the patterns of airflow carrying the pollutants. Herein, we propose a methodology for optimizing the portable air cleaner placement to maximize its effectiveness using artificial intelligence technology. To build an artificial intelligence model, we obtained the data on airflow patterns for different room shapes and locations of the portable air cleaner through numerical simulations. We utilized floor-plan image data to simplify the handling of complex geometric information related to portable air cleaner placements. The artificial intelligence model extracted geometric features from the floor plan and predicted the effectiveness of the portable air cleaner. The predicted results revealed that the model recommended the location with the highest effectiveness as optimal. The artificial intelligence model achieved a high prediction accuracy of 91.2% and precisely determined the optimal location in rooms with varying shapes. This approach can elucidate the complex relationship between geometric placements and airflow characteristics. Furthermore, the artificial intelligence model can be used as a powerful decision-making tool for indoor air quality management in the building environment.

Shell to pay $10 million for air permit violations

Shell will pay nearly $10 million to the Pennsylvania Department of Environmental Protection (DEP) and communities in western Pennsylvania for repeated air permit violation at its multibillion-dollar petrochemical plant in Beaver County, Pennsylvania. Under a consent order and agreement with the office of Governor Josh Shapiro and the DEP, Shell will pay a civil penalty of $4.9 million, a portion of which will be paid to local communities. Shell will spend an additional $5 million for environmental projects to benefit those communities. In all, $6.2 million will go to communities surrounding the plant. According to the DEP, the plant, which started operations in November, exceeded emission limits in recent months for volatile organic compounds (VOCs), carbon monoxide, nitrogen oxides, and hazardous air pollutants. The DEP also cited Shell for flaring violations, malodor violations at its wastewater treatment plant, and other violations. According to the consent agreement, Shell will pay monthly

Sociodemographic Disparities in Mercury Exposure from United States Coal-Fired Power Plants.

Hazardous air pollutants emitted by United States (U.S) coal-fired power plants have been controlled by the Mercury and Air Toxics Standards (MATS) since 2012. Sociodemographic disparities in traditional air pollutant exposures from U.S. power plants are known to occur but have not been evaluated for mercury (Hg), a neurotoxicant that bioaccumulates in food webs. Atmospheric Hg deposition from domestic power plants decreased by 91% across the contiguous U.S. from 6.4 Mg in 2010 to 0.55 Mg in 2020. Prior to MATS, populations living within 5 km of power plants (n = 507) included greater proportions of frequent fish consumers, individuals with low annual income and less than a high school education, and limited English-proficiency households compared to the US general population. These results reinforce a lack of distributional justice in plant siting found in prior work. Significantly greater proportions of low-income individuals lived within 5 km of active facilities in 2020 (n = 277) compared to plants that retired after 2010, suggesting that socioeconomic status may have played a role in retirement. Despite large deposition declines, an end-member scenario for remaining exposures from the largest active power plants for individuals consuming self-caught fish suggests they could still exceed the U.S. Environmental Protection Agency reference dose for methylmercury.

Hazardous air pollutant emissions estimates from wildfires in the wildland urban interface.

Fires that occur in the wildland urban interface (WUI) often burn structures, vehicles, and their contents in addition to biomass in the natural landscape. Because these fires burn near population centers, their emissions may have a sizeable impact on public health, necessitating a better understanding of criteria and hazardous air pollutants emitted from these fires and how they differ from wildland fires. Previous studies on the toxicity of emissions from the combustion of building materials and vehicles have shown that urban fires may emit numerous toxic species such as hydrogen cyanide, hydrogen fluoride, hydrogen chloride, isocyanates, polycyclic aromatic hydrocarbons (PAHs), dioxins and furans, and a range of toxic organic compounds (e.g. benzene toluene, xylenes, styrene, and formaldehyde) and metals (e.g. lead, chromium, cadmium, and arsenic). We surveyed the literature to create a compendium of emission factors for species emitted from the combustion of building and vehicle materials and compared them with those from wildland fires. Emission factors for some toxic species like PAH and some organic compounds were several orders of magnitude greater than those from wildfires. We used this emission factor compendium to calculate a bounding estimate of the emissions from several notable WUI fires in the western United States to show that urban fuels may contribute a sizeable portion of the toxic emissions into the atmosphere. However, large gaps remain in our understanding of the fuel composition, fuel consumption, and combustion conditions in WUI fires that constrain our ability to estimate the impact of WUI fires.

Occupational exposure and personal exposure to hazardous air pollutants in underground metro stations and factors causing poor indoor air quality

Occupational exposure and personal exposure to hazardous air pollutants in underground metro stations and factors causing poor indoor air quality

Airborne Air Pollutant Emission Characteristics of Mobile Vehicles in Taiwan

This study examines the air pollutant emission characteristics, activity intensity, and trends of mobile sources from 2013 to 2021. The target pollutants include criteria pollutants (fine particulate matters, nitrogen oxides, and hydrocarbons) and hazardous air pollutants (benzene, formaldehyde, and BaP). The results indicated that the activity intensity levels of road mobile sources in Taiwan were148 × 109, 156 × 109, 159 × 109, and 155 × 109 km/year in 2013, 2016, 2019, and 2021, respectively, with the largest proportion attributed to gasoline passenger cars (42.6%), followed by four-stroke motorcycles (32.6%). An emission factor of PM2.5 was estimated by EPA’s MOVES (Motor Vehicle Emission Simulator) model, and the results showed that the emission sequence was diesel > gasoline > motorcycle; the NOx emission factor was estimated using the MOBILE6.2 model, and the results showed that the order was diesel > gasoline > motorcycle; the HC emission factor was compiled with the use of gasoline vehicle dynamometer data, and the results showed that motorcycle > gasoline vehicles. Further results showed that the emission sequence for benzene was motorcycle > gasoline ≥ diesel; the formaldehyde emission sequence was diesel > motorcycle ≥ gasoline. The BaP emission factors of different vehicle types were estimated using MOVES, and the emission factors of old heavy-duty diesel vehicles were the highest.