Hazardous Air Pollutants Research Articles

Valorization of hazardous COVID-19 mask waste while minimizing hazardous byproducts using catalytic gasification

This study proposes a method to valorize hazardous waste such as used COVID-19 face mask via catalytic gasification over Ni-loaded ZSM-5 type zeolites. The 25% Ni was found as an optimal loading on ZSM-5 in terms of H2 production. Among different zeolites (ZSM-5(30), ZSM-5(80), ZSM-5(280), mesoporous (m)-ZSM-5(30), and HY(30)), 25% Ni/m-ZSM-5(30) led to the highest H2 selectivity (45.04 vol%), most likely because of the highest Ni dispersion on the m-ZSM-5(30) surface, high porosity, and acid site density of the m-ZSM-5(30). The content of N-containing species (e.g., caprolactum and nitriles) in the gasification product was also reduced, when steam was used as gasifying agent, which is the source of potentially hazardous air pollutants (e.g., NOx). The increase in the SiO2/Al2O3 ratio resulted in lower tar conversion and lower H2 generation. At comparable conditions, steam gasification of the mask led to ~15 vol% higher H2 selectivity than air gasification. Overall, the Ni-loaded zeolite catalyst can not only suppress the formation of hazardous substances but also enhance the production of hydrogen from the hazardous waste material such as COVID-19 mask waste.

Improving quantitative analysis of spark-induced breakdown spectroscopy: Multivariate calibration of metal particles using machine learning

We have recently developed a low-cost spark-induced breakdown spectroscopy (SIBS) instrument for in-situ analysis of toxic metal aerosol particles that we call TARTA (toxic-metal aerosol real time analyzer). In this work, we applied machine learning methods to improve the quantitative analysis of elemental mass concentrations measured by this instrument. Specifically, we applied least absolute shrinkage and selection operator (LASSO), partial least squares (PLS) regression, principal component regression (PCR), and support vector regression (SVR) to develop multivariate calibration models for 13 metals (e.g., Cr, Cu, Mn, Fe, Zn, Co, Al, K, Be, Hg, Cd, Pb, and Ni), some of which are included on the US EPA hazardous air pollutants (HAPS) list. The calibration performance, adjusted coefficient of determination (R2) and normalized root mean square error (RMSE), and limit of detection (LOD) of the proposed models were compared to those of univariate calibration models for each analyte. Our results suggest that machine learning models tend to have better prediction accuracy and lower LODs than conventional univariate calibration, of which the LASSO approach performs the best with R2 > 0.8 and LODs of 40–170 ng m−3 at a sampling time of 30 min and a flow rate of 15 l min−1. We then assessed the applicability of the LASSO model for quantifying elemental concentrations in mixtures of these metals, serving as independent validation datasets. Ultimately, the LASSO model developed in this work is a very promising machine learning approach for quantifying mass concentration of metals in aerosol particles using TARTA.

Indoor Coal Combustion for Heating Exacerbates CO2 Exposure Approaching Harmful Levels

Nearly three billion people still rely on traditional solid fuels for daily activities, which emit large amounts of many hazardous air pollutants, as well as CO2 indoors. Indoor CO2 should not be just a proxy for air exchange, as elevated CO2 exposure could pose a variety of direct risks to human health, including mental and physiological diseases. Here, we evaluated indoor CO2 levels in rural coal-use households to test the hypothesis that the incremental CO2 associated with indoor coal use may result in chronic exposure close to harmful levels. Significantly elevated daily concentrations of indoor CO2 were observed of 750 ± 230 ppm indoors in comparison with that outdoors. More than 12% of the daily data exceeded the threshold of 1000 ppm, with a maximum of up to 2960 ppm, at which level a variety of health risks can potentially occur. Internal sources contributed ∼280 ppm to indoor CO2 exposure during the heating period, wherein ∼50% was from coal combustion. The study sheds light on the crucial role of the widespread exposure to indoor CO2 and collaboration efforts in considering CO2 as an indoor air pollutant.

Estimated Mortality and Morbidity Attributable to Smoke Plumes in the United States: Not Just a Western US Problem.

As anthropogenic emissions continue to decline and emissions from landscape (wild, prescribed, and agricultural) fires increase across the coming century, the relative importance of landscape‐fire smoke on air quality and health in the United States (US) will increase. Landscape fires are a large source of fine particulate matter (PM2.5), which has known negative impacts on human health. The seasonal and spatial distribution, particle composition, and co‐emitted species in landscape‐fire emissions are different from anthropogenic sources of PM2.5. The implications of landscape‐fire emissions on the sub‐national temporal and spatial distribution of health events and the relative health importance of specific pollutants within smoke are not well understood. We use a health impact assessment with observation‐based smoke PM2.5 to determine the sub‐national distribution of mortality and the sub‐national and sub‐annual distribution of asthma morbidity attributable to US smoke PM2.5 from 2006 to 2018. We estimate disability‐adjusted life years (DALYs) for PM2.5 and 18 gas‐phase hazardous air pollutants (HAPs) in smoke. Although the majority of large landscape fires occur in the western US, we find the majority of mortality (74%) and asthma morbidity (on average 75% across 2006–2018) attributable to smoke PM2.5 occurs outside the West, due to higher population density in the East. Across the US, smoke‐attributable asthma morbidity predominantly occurs in spring and summer. The number of DALYs associated with smoke PM2.5 is approximately three orders of magnitude higher than DALYs associated with gas‐phase smoke HAPs. Our results indicate awareness and mitigation of landscape‐fire smoke exposure is important across the US.

Effects of Bioadditives and Commercial Additive on the Performance and Exhaust Emissions of a Gasoline Engine

One of our era’s greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. However, future climate change may exacerbate such human health impacts by increasing the frequency and duration of weather conditions that enhance the exposure to air pollution. Jakarta’s expanding fleet of motor vehicles is a key target of urgently needed actions to curb the hazardous air pollution in the city. This paper highlights the technologies and policies to reduce direct emissions from new and in-use cars, trucks, and buses in the city. Such policies, coupled with the promotion of mass transit, non-motorized transport, and other smart growth measures aimed at reducing transport demand, can significantly diminish the adverse effects of transportation on local air quality and public health in Jakarta, and spur similar actions across Indonesia. One of them is the addition of bioadditives (essential oils) and commercial additives that are widely sold in the market. In this study, the effects of essential oils (citronella oil and clove oil) as bioadditives and commercial additive on the performance and exhaust emissions of a single-cylinder, four-stroke gasoline engine was investigated, where both oils were blended with gasoline with a research octane number of 88. Based on the results, the maximum reduction in fuel consumption (33.33%) was obtained at an engine load of 43% when pure gasoline (G88) was blended with 0.1% of citronella oil and 0.1% of clove oil. This test fuel was labelled as BA2. The average reduction in fuel consumption was 18.54% for this test fuel. The thermal efficiency of the BA2 blend was higher even though it had the lowest volumetric efficiency compared with other blends. The unburned hydrocarbon (HC) and carbon monoxide emissions for the G88 fuel were 7 ppm and 0.202%, respectively, whereas the values were 20 ppm and 0.289%, respectively for the G88 fuel blended with Cleanoz commercial additive (CA1 blend). The HC and CO emissions were 11 ppm and 0.386%, respectively, for the G88 fuel blended with 0.1% of patchouli oil and 0.1% of clove oil (BA1 blend) whereas the values were 26 ppm and 0.631%, respectively, for the BA2 blend. Even though the BA2 blend had the highest HC and CO emissions, the values were still below the permissible limits for automotive vehicles in Indonesia.

Environmental exposures and anti-Müllerian hormone: a mixture analysis in the US based Nurses’ Health Study II (NHSII)

BACKGROUND AND AIM: Previous studies have linked exposures such as air pollution and greenness with anti-Müllerian hormone (AMH), a marker of ovarian reserve. However, the association of multiple environment factors has not been addressed. We aimed to assess the impact of a mixture of environmental exposures on AMH. METHODS: A total of 2,449 premenopausal women in the NHSII, a US nationwide prospective cohort who provided blood samples for AMH assay were included. Exposure to greenness, particulate matter, noise, outdoor light at night (LAN), ultraviolet radiation, and 6 hazardous air pollutants (HAPs) (1,3-butadine, benzene, diesel particulate matter, formaldehyde, methylene chloride, and tetrachloroethylene) were available at all residential addresses since 1989. We first estimated associations with AMH in single exposure models adjusting for relevant covariates and then explored patterns of exposure using principal component analysis (PCA). Hierarchical Bayesian kernel machine regression (BKMR) was used to select key exposures and estimate the joint associations. We further conducted subgroup analyses by age at blood draw. RESULTS:Median age at blood collection was 40. Single exposure models showed negative associations of AMH with benzene (percentage reduction in AMH per interquartile range (IQR) increase = 5.44%, 95%CI=1.05, 9.62) and formaldehyde (percentage reduction in AMH per IQR increase = 6.04%, 95%CI=1.72, 10.17) but not the other exposures. PCA identified four major exposure patterns and only the one with high exposure to HAPs and LAN was associated with lower AMH. Hierarchical BKMR selected benzene, formaldehyde, and greenness as important exposures, and suggested an inverse joint association with AMH (percentage reduction comparing all exposures at the 75th percentile to median= 8.12%, 95%CI=0.54, 15.12). The observed associations were mainly found among women aged above 40. CONCLUSIONS:We found exposure to benzene and formaldehyde to be consistently associated with lower AMH levels. Older reproductive aged women were the most susceptible, suggesting these exposures may accelerate reproductive aging. KEYWORDS: multi-pollutant, mixtures analysis, reproductive outcomes

Health Cost Estimation of Traffic-Related Air Pollution and Assessing the Pollution Reduction Potential of Zero-Emission Vehicles in Toronto, Canada

Fossil fuel vehicles, emitting air toxics into the atmosphere, impose a heavy burden on the economy through additional health care expenses and ecological degradation. Air pollution is responsible for millions of deaths and chronic and acute health problems every year, such as asthma and chronic obstructive pulmonary disease. The fossil-fuel-based transportation system releases tons of toxic gases into the atmosphere putting human health at risk, especially in urban areas. This analysis aims to determine the economic burden of environmental and health impacts caused by Highway 401 traffic. Due to the high volume of vehicles driving on the Toronto Highway 401 corridor, there is an annual release of 3771 tonnes of carbon dioxide equivalent (CO2e). These emissions are mainly emitted onsite through the combustion of gasoline and diesel fuel. The integration of electric and hydrogen vehicles shows maximum reductions of 405–476 g CO2e per vehicle-kilometer. Besides these carbon dioxide emissions, there is also a large amount of hazardous air pollutants. To examine the impact of air pollution on human health, the mass and concentrations of criteria pollutants of PM2.5 and NOx emitted by passenger vehicles and commercial trucks on Highway 401 were determined using the MOVES2014b software. Then, an air dispersion model (AERMOD) was used to find the concentration of different pollutants at the receptor’s location. The increased risk of health issues was calculated using hazard ratios from literature. Finally, the health cost of air pollution from Highway 401 traffic was estimated to be CAD 416 million per year using the value of statistical life, which is significantly higher than the climate change costs of CAD 55 million per year due to air pollution.

Autism spectrum disorder and molecular imaging following environmental stress: Functional aspects of the risk using multi-omics

Autism Spectrum Disorder (ASD) is characterized by complicated phenotypic symptoms, including intervention with social activity, communication, and unusually behavioral abnormality. ASD is a lifelong developmental condition affecting one in 88 children and is considered one of today's most urgent public health challenges. Individuals with ASD tend to respond inappropriately in conversation and may struggle to build relationships. Currently, the prime cause of ASD remains unclear, even though emerging findings emphasize the role of genetic and environmental factors in the development of autistic behavior could be examined. At present, risks such as exposure to unknown chemicals as an environmental factor in ASD are less appreciated. This review will discuss potential risks include air pollution and particle matters in alignment with detection strategies, like multidimensional Omics and the transcriptomic approach, which may empower the capability of predicting potential risk from gene expression to phenotype level as a hallmark of transformation outcome. In addition, this genomic-driven validation process saves time and quality of accuracy in the process of finding molecular determinants in the early stage of disease onset. Currently, the genomics era brings prediction models with various algorithms, and its intervention alternatives speed up to analyze the environmental risk of chemical stressors, such as hazardous chemicals, air pollutants, and/or nanoparticles, in compliance with regulatory measures of exploring molecular determinants associated with chronic disease and metabolic disorders. The value chain of disease prevention along with surveillance platform closely interacts with the prediction of risk assessment using a molecular-based platform. Efficacy of a sequential workout, including exploring, monitoring, and the translational application process in cellular or in vitro systems, could crosstalk with a transgenic animal model. Targeting molecule implication, such as gain- or loss-of-functional reverse genetic technology to verify its functional analysis, multi-dimensional omics could be beneficial in the field of environmental risk assessment, including safety evaluation: food and drug screening in ASD combined with imaging technology.

Removing NOx Pollution by Photocatalytic Building Materials in Real- Life: Evaluation of Existing Field Studies

The NOx gasses (NO and NO2) are among the most important air pollutants due to the toxicity of NO2, as well as the role of NOx in the tropospheric oxidation of Volatile Organic Carbons (VOCs), contributing to the formation of other hazardous air pollutants. Air pollution is one of the biggest health threats worldwide; hence reducing NOx levels is an important objective of the UN sustainable development goals, e.g., #3, “Good health and well-being” and #11 “Sustainable cities and communities.”Photocatalysis using TiO2 and light is a promising technique for removing NOx along with other pollutants, as demonstrated on a laboratory scale. Furthermore, a long-range of real-life test studies of varying scales have been conducted during the past two decades. The results of these studies have been conflicting, with some studies reporting no effect on the ambient air quality and others reporting significant reductions of NOx levels. However, the studies are very difficult to compare and assess due to the different approaches used, which consequently vary in quality. In this review, we aim to develop a set of objective evaluation criteria to assess the quality of the individual studies in order to simplify the interpretation and comparison of the existing studies. Moreover, we propose some guidelines for future test studies. Furthermore, the approaches and main conclusion from 23 studies are independently assessed and discussed herein.

Suppression of the hazardous substances in catalytically upgraded bio-heavy oil as a precautious measure for clean air pollution controls

Bio-heavy oil (BHO) is a renewable fuel, but its efficient use is problematic because its combustion may emit hazardous air pollutants (e.g., polycyclic aromatic hydrocarbon (PAH) compounds, NOx, and SOx). Herein, catalytic fast pyrolysis over HZSM-5 zeolite was applied to upgrading BHO to drop-in fuel-range hydrocarbons with reduced contents of hazardous species such as PAH compounds and N- and S-containing species (NOx and SOx precursors). The effects of HZSM-5 desilication and linear low-density polyethylene (LLDPE) addition to the feedstock on hydrocarbon production were explored. The apparent activation energy for the thermal decomposition of BHO was up to 37.5% lowered by desilicated HZSM-5 (DeHZSM-5) compared with HZSM-5. Co-pyrolyzing LLDPE with BHO increased the content of drop-in fuel-range hydrocarbons and decreased the content of PAH compounds. The DeHZSM-5 was effective in producing drop-in fuel-range hydrocarbons from a mixture of BHO and LLDPE and suppressing the formation of N- and S-containing species and PAH compounds. The DeHZSM-5 enhanced the hydrocarbon production by up to 58.5% because of its enhanced porosity and high acid site density compared to its parent HZSM-5. This study experimentally validated that BHO can be upgraded to less hazardous fuel via catalytic fast co-pyrolysis with LLDPE over DeHZSM-5.

Investigating the Spread of Coronavirus Disease via Edge-AI and Air Pollution Correlation

Coronavirus Disease 19 (COVID-19) is a highly infectious viral disease affecting millions of people worldwide in 2020. Several studies have shown that COVID-19 results in a severe acute respiratory syndrome and may lead to death. In past research, a greater number of respiratory diseases has been caused by exposure to air pollution for long periods of time. This article investigates the spread of COVID-19 as a result of air pollution by applying linear regression in machine learning method based edge computing. The analysis in this investigation have been based on the death rates caused by COVID-19 as well as the region of death rates based on hazardous air pollution using data retrieved from the Copernicus Sentinel-5P satellite. The results obtained in the investigation prove that the mortality rate due to the spread of COVID-19 is 77% higher in areas with polluted air. This investigation also proves that COVID-19 severely affected 68% of the individuals who had been exposed to polluted air.

Compliance with hand sanitizer quality during the SARS-CoV-2 pandemic: Assessing the impurities in an ethanol plant

Using alcohol-based disinfectants is an effective method for preventing the spread of COVID-19. However, non-traditional manufacturers of alcohol-based disinfectants, such as ethanol plants, need to undergo additional treatment to curb their impurities to limits set by the Food and Drug Association (FDA) to produce alcohol-based disinfectants. To transform them to disinfectant-grade alcohol, 17 process streams in a dry-mill ethanol plant were analyzed to determine the quality parameters for acetaldehyde, acetal, propanol, methanol, and water, including chemical oxygen demand, total suspended solids, and nutrients. Results suggest that the process stream generated by the distillation column requires further treatment because the acetaldehyde and acetal concentrations are significantly higher than the impurity limit set by the FDA. The addition of a second distillation column could be a potential method for addressing impurities and it will have minimal influence on hazardous air pollutant generation and water use.

The atmospheric lead emission, deposition, and environmental inequality driven by interprovincial trade in China

Lead (Pb) as a hazardous air pollutant has raised widespread concerns due to its adverse and toxic effects on the ecological environment and human health. Here we integrated the multi-regional input-output (MRIO) model and an atmospheric transport model to examine regional environmental inequality (REI) index induced by Pb emission transfers, and to evaluate the impacts of interprovincial trade on regional atmospheric Pb concentrations and dry deposition fluxes in China in 2012. In 2012, approximately 57.4% ~ 72.6% of Pb emissions in well-developed eastern regions (Beijing-Tianjin, Yangtze River Delta (YRD)) and the southern seaboard of China were embodied in other regions in China subject to the demands from these well-developed regions to industrial products and services. Our results, based on the net virtual flows of Pb emission and value-added, indicate that most provinces in the eastern seaboard of China outsource Pb emission and benefit from the interprovincial trade by reducing their Pb emissions. REI indexes show that the well-developed Guangdong province outsources its Pb emission but has low economic gains. Many less-developed provinces in central China enhance virtual Pb emission inflow but have high economic gains. Whereas, inland provinces in western China not only experience Pb emission increase, but also suffer from indirect economic loss due to trade with well-developed provinces to meet their increasing demands to Pb emission abundant industrial products from these provinces in eastern China which are mostly provided by less-developed but energy and mineral product abundant provinces in western China. For example, the province pair with highest REI index was Jiangsu-Inner Mongolia (REI = 2.47), which revealed that Jiangsu was the largest beneficiary which exported 37.2 t of net Pb emission and gained value-added of 521.4 billion RMB through trade with Inner Mongolia which suffered from both virtual Pb inflow and economic loss in 2012. As a result of interprovincial trade, Pb dry deposition in central and eastern China was decreased but increased in western China. Overall, interprovincial trade reduced 17.6% of atmospheric Pb dry deposition in China.

Inequalities in Exposure to Ambient Air Neurotoxicants and Disparities in Markers of Neurodevelopment in Children by Maternal Nativity Status.

Exposure levels to environmental pollutants vary significantly among different populations. These inequities in exposure to hazardous air pollutants (HAP) among different populations can contribute to disparities in neurodevelopmental outcomes. The aim of this study was to determine if exposure to HAP varies by maternal nativity status, a demographic marker often overlooked in the study of health disparities. We also assessed if those inequalities in exposure levels are associated with neurodevelopmental measures in young children. To do this, we obtained data from the Early Childhood Longitudinal Study-Birth cohort (ECLS-B), a nationally representative sample of children born in the U.S. in the year 2001 (n = 4750). Bayley’s Short Form-Research Edition (BSF-R) was used to measure cognitive development at 2 years of age. Using residential location at nine months of age, participants were assigned exposures to ten HAPs identified as potentially neurotoxic. Linear regression models were used to assess the joint effect of maternal nativity status and HAP exposure on neurodevelopment. Results showed inequities in exposure levels to ten different HAPs among the populations, as approximately 32% of children of foreign-born mothers were exposed to high levels of HAPs, compared to 21% of children born to U.S.-born mothers. Adjusting for socioeconomic factors, both isophorone exposure (a marker of industrial pollution) (−0.04, 95% CI, −0.12, 0.04) and maternal nativity status (−0.17, 95% CI, −0.27, −0.06) were independently associated with lower standardized BSF-R mental scores in children. Interaction between nativity status and isophorone was not statistically significant, but the change in mental scores associated with isophorone exposure was greater in children of foreign-born mothers compared to children of U.S.-born mothers (−0.12, vs. −0.03, p = 0.2). In conclusion, exposure to HAPs within the highest quartile was more commonly found among children of foreign-born mothers as compared to children of US-born mothers, indicating inequities in pollutant exposure by nativity status within urban populations. Exposures associated with nativity status may negatively contribute to children’s neurodevelopment.

Emission Characteristics of Hazardous Air Pollutants from Medium-Duty Diesel Trucks Based on Driving Cycles

Studies on the characteristics of hazardous air pollutants (HAPs) in the emissions of medium-duty diesel trucks are significantly insufficient compared to those on heavy-duty trucks. This study investigated the characteristics of regulated pollutants and HAPs, such as volatile organic compounds (VOCs), aldehydes, and polycyclic aromatic hydrocarbons (PAHs), and estimated non-methane hydrocarbon (NMHC) speciation in the emissions of medium-duty diesel trucks. Ten medium-duty diesel trucks conforming to Euros 5 and 6 were tested for four various driving cycles (WLTC, NEDC, CVS-75, and NIER-9) using a chassis dynamometer. In an urban area such as Seoul, CO and NMHC emissions were increased because of its longer low-speed driving time. NOx emissions were the highest in the high-speed phase owing to the influence of thermal NOx. PM emissions were almost not emitted because of the DPF installation. Alkanes dominated non-methane volatile organic compound (NMVOC) emissions, 36–63% of which resulted from the low reaction of the diesel oxidation catalyst. Formaldehyde emissions were the highest for 35–53% among aldehydes irrespective of driving cycles. By sampling the particle-phase of PAHs, we detected benzo(k)fluoranthene and benzo(a)pyrene and estimated the concentrations of the gas-phase PAHs with models to obtain the total PAH concentrations. In the particle portion, benzo(k)fluoranthene and benzo(a)pyrene were over 69% and over 91%, respectively. The toxic equivalency quantities of benzo(k)fluoranthene and benzo(a)pyrene from NIER-9 (cold) for both Euro 5 and Euro 6 vehicles were more than five times higher than those of NIER (hot) and NEDC. In the case of NMHC speciation, formaldehyde emissions were the highest for 10–45% in all the driving cycles. Formaldehyde and benzene must be controlled in the emissions of medium-duty diesel trucks to reduce their health threats. The results of this study will aid in establishing a national emission inventory system for HAPs of mobile sources in Korea.

Volatile Organic Compounds Emitted from Air Fresheners

Air fresheners contain volatile organic compounds (VOCs), some of which are possible hazardous air pollutants, carcinogens, or chemicals associated with adverse health effects such as asthma. This screening study identifies VOCs emitted from two types of air fresheners. Plug-in air fresheners are household products that release scents from a heated liquid. Little Tree air fresheners are commonly-used solid devices designed to hang in from the rear view mirror in cars. VOCs that were released from heated samples of air fresheners were identified by gas chromatography mass spectroscopy (GCMS). In a pilot study to characterize how air fresheners affect air quality in real settings, air samples were collected on solid-phase microextraction (SPME) field samplers in a home setting and inside a vehicle, before and during air-freshener use. This pilot demonstrated the potential for SPME field samplers to track changes in VOC levels in real-life settings.

Urban Air Pollution and Mental Stress: A Nationwide Study of University Students in China.

Background: Studies exploring the relationship between air pollution levels and mental stress have rarely been done, and no studies have been done comparing university student mental stress levels based on regional air pollution levels.Objectives: The objective of this study was to evaluate the association between air pollution and mental stress among university students.Methods: Participants were 11,942 students, who were identified through a multistage survey sampling process conducted in 50 universities. Regional air pollution levels were retrieved from a national database, and mental stress was measured using a perceived stress scale. Both unadjusted and adjusted methods were utilized in the data analyses.Results: Mental stress prevalence was 36.9% (95% Confidence Interval: 24.4–49.5%). The final model indicated that regional air pollution levels were positively associated with students' mental stress.Conclusions: This study provided new and direct evidence of the health hazards of air pollution. The findings underscore the need to develop and implement stringent environmental protection policies, while simultaneously raising public awareness of environmental protection.

COVID-19 outbreak and air quality of Lahore, Pakistan: evidence from asymmetric causality analysis.

This paper aims to examine the impact of COVID-19 restrictions on the air quality of Lahore city of Pakistan for the period 26th February, 2020 to 31st August, 2020. The study employs asymmetrical Granger causality tests for analyzing the effects of COVID-19 cases and deaths on particulate matter (PM2.5) emissions in the city. The results show positive shocks in COVID-19 cases and deaths improve the air quality of the city. This implies that the pandemic has lowered down environmental pressure in one of the top most polluted cities of the world. Further, the problem of hazardous air pollution in Lahore city is manmade mainly caused by everyday human activities. When these human activities were restricted owing to a rise in COVID-19 cases and deaths, the air pollution in the city resultantly reduces. Therefore, this study recommends controlling unnecessary production and consumption activities that degrades the environment so that air pollution in the city can be manageable after the COVID-19.

Elemental composition of indoor and outdoor coarse particulate matter at an inner-city high school

Paired PM10 and fine particulate matter (PM2.5) samples were collected indoor and outdoor at a fully mechanically ventilated high school in the ultraindustrialized ship channel region of Houston, Texas over a two-month period. The primary foci of this research are to measure the elemental composition of ambient outdoor and indoor coarse particulate matter (PM10-2.5), characterize aerosol infiltration/ventilation, and obtain clues to their origins. Several metallic hazardous air pollutants were detected inside the school but at concentrations lower than even the most rigorous indoor air quality benchmarks. Only chromium may have potentially posed a hazard based on indoor air quality standards set by the California Environmental Protection Agency. Indoor-to-outdoor (I/O) mass abundance ratios for some metals (Li, Be, Si, Ti, Cr, Co, Ni, Zn, As, Se, Zr, Cd, Sn, Sb, Hf, and Pb) were significantly greater than 1 in PM10-2.5, suggesting corresponding indoor sources in the PM10-2.5 size range. Some other metals (Al, K, Ca, V, Mn, Fe, Cu, Ga, Rb, Sr, Y, Mo, Ce, Pr, Nd, Sm, Gd, Dy, Yb, and U) in PM10-2.5 had I/O ratios close to one suggesting they had predominantly outdoor origins. Enrichment factors of several metals including light rare earths (e.g. Cu, Sb, Pb, Mo, Cd, La, Ce, Pr, Nd, and Sm) with respect to local soil were overall the highest both indoors and outdoors, illustrating their anthropogenic origins. Several lines of evidence including light lanthanoid ratios, simultaneous La–Ce-Sm variations (ternary diagrams), and correlations with cracking catalysts indicated that petroleum refineries are principally responsible for the elevated lanthanoid concentrations. Rare earth element analysis revealed shifts between transient catalyst releases from petroleum refining operations and windblown soil resuspension as their dominant sources.

Contributions of biomass burning to global and regional SO2 emissions

Harmful SO2 largely originates from coal and oil combustions, but in some areas the biomass burning contribution could not be ignored. Here, we evaluated SO2 emissions from biomass burning (BB-SO2) with largely focusing on regional difference and temporal trends in the relative contributions of biomass burning from different sectors. Globally, the biomass burning emitted 4.26 (3.20–6.20) Tg SO2 in 2014, contributing 4.0% of the total SO2 emissions stemming from anthropogenic sources and natural open fires. But in some African and South Asian countries, biomass burning was a major source of SO2 with the contribution as high as 80–90%. Regarding sector contributions of biomass SO2, open fires contributed nearly half, followed by the residential sector (~29%) on the global scale, however, substantially different profiles were revealed across countries. Residential sector is the largest anthropogenic BB-SO2 source in the developing countries, while in the developed countries, industry and energy production were the two main anthropogenic BB-SO2sources. From 1960 to 2014, biomass SO2 emission, either the absolute amount or the relative contribution to the total, increased in the U.S. and Europe, and the contributions were over 20% in some countries. The biomass burning SO2 emission showed an increasing trend in India and a unimodal change in China, while a decreasing trend in the relative contributions were revealed in these two largest developing countries, which were 2.7% and 0.8%, respectively in 2014. With unignorable biomass burning contribution to SO2, as well as other hazardous air pollutants, in some regions, it is suggested that in assessing climate and health impacts of promoted biomass utilization when phasing out of fossil fuels, multiple components should be co-evaluated.