Reduction In PM2 Research Articles

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.

Quantifying the potential effects of air pollution reduction on population health and health expenditure in Taiwan

Air pollution, particularly ambient fine particulate matter (PM2.5) pollution, poses a significant risk to public health, underscoring the importance of comprehending the long-term impact on health burden and expenditure at national and subnational levels. Therefore, this study aims to quantify the disease burden and healthcare expenditure associated with PM2.5 exposure in Taiwan and assess the potential benefits of reducing pollution levels. Using a comparative risk assessment framework that integrates an auto-aggressive integrated moving average model, we evaluated the avoidable burden of cardiopulmonary diseases (including ischemic heart disease, stroke, chronic obstructive pulmonary disease, lung cancer, and diabetes mellitus) and related healthcare expenditure under different air quality target scenarios, including status quo and target scenarios of 15, 10, and 5 μg/m3 reduction in PM2.5 concentration. Our findings indicate that reducing PM2.5 exposure has the potential to significantly alleviate the burden of multiple diseases. Comparing the estimated attributable disease burden and healthcare expenditure between reference and target scenarios from 2022 to 2050, the avoidable disability-adjusted life years were 0.61, 1.83, and 3.19 million for the 15, 10, and 5 μg/m3 target scenarios, respectively. Correspondingly, avoidable healthcare expenditure ranged from US$ 0.63 to 3.67 billion. We also highlighted the unequal allocation of resources and the need for policy interventions to address health disparities due to air pollution. Notably, in the 5 μg/m3 target scenario, Kaohsiung City stands to benefit the most, with 527,368 disability-adjusted life years avoided and US$ 0.53 billion saved from 2022 to 2050. Our findings suggest that adopting stricter emission targets can effectively reduce the health burden and associated healthcare expenditure in Taiwan. Overall, this study provides policymakers in Taiwan with valuable insights for mitigating the negative effects of air pollution by establishing a comprehensive framework for evaluating the co-benefits of air pollution reduction on healthcare expenditure and disease burden.

Effects of reformed exhaust gas recirculation (REGR) of ethanol-gasoline fuel blends on the combustion and emissions of gasoline direct injection (GDI) engine

Transportation is one of fast-growing sources of greenhouse gas emission worldwide. Road transport accounts as the main cause of HC, CO, NOX, CO2, and PM emissions. Ethanol blended fuel could improve engine performance and reduce both gaseous and PM emissions. Meanwhile, reformed exhaust gas recirculation (REGR) is introduced to achieve simultaneous reduction of NOX and PM from gasoline engines. In this work, the effect of REGR on combustion characteristics, and emissions of the gasoline direct injection (GDI) engine fuelled with ethanol-gasoline fuel blends (E10 and E20) was investigated. The H2 and CO mixture were used as a simulated REGR charge which was fed to the GDI engine’s intake manifold. The H2/CO ratio was determined via modelling of ethanol-gasoline fuel blend reforming based on equilibrium analysis. Moreover, the characteristics of PM emission (e.g. size distribution, primary particle size, morphology) were explored using TEM imaging. The results revealed that REGR could simultaneously improve both the engine thermal efficiency and engine-out emissions. A total number of PM particles and average primary particle size were reduced and compared with baseline (no-EGR) condition. An insight from this investigation can be used for designing control strategies to reduce the negative impact of internal combustion engine usage on human health and environment.

Phytoremediation of indoor air pollutants from construction and transport by a moveable active green wall system

No sustainable, economical and scalable systems are currently available for the direct removal of construction and transport related air pollutants from working environments in these locations. Active green walls have previously demonstrated the capacity to effectively filter NO2, O3, and PM2.5 from indoor and roadside air. This project assessed the air quality provided by a portable active green wall in a construction site office involved in a construction upgrade of train depot, and compared it to a matched reference office to ascertain the active green wall's potential to enhance air quality. Through comparisons between time-matched samples, we established differences in air quality between the ambient and filtered air streams, and thus calculated the single pass removal efficiency provided by the active green wall for each pollutant. A comparison between the two site offices demonstrated that the active green wall produced significant improvements on the air quality of this unique indoor environment, with reductions in PM2.5 and O3 detected, with the active green wall achieving single pass removal efficiencies of 56.42 ± 21.02% and 20.73 ± 0.87% PM2.5 and O3, respectively. The active green wall also caused a small increase in dew point, but had no effect on humidity and temperature, possibly due to the small scale of the system relative to the volume of the test structure. The findings suggest phytoremediation may be an effective method for removing construction and transport associated PM2.5 and O3. Conversely, future research is needed to investigate NO2 removal, with substrate developments potentially required to address this.

Reduction of household air pollution through clean fuel intervention and recovery of cellular immune balance

BackgroundWe conducted a clean fuel intervention trial (Bangladesh Global Environmental and Occupational Health (GEOHealth) (NCT02824237) with liquefied petroleum gas (LPG) for 26 months among rural Bangladeshi women chronically exposed to household air pollution (HAP) from biomass fuel (BMF) use. We aimed to evaluate the effect of HAP reduction following LPG intervention on immune response outcome. MethodsWe supplied LPG cook stove and refills in cylinder in 200 households for 26 months. We measured personal exposure to HAP [particulate matter 2.5 (PM2·5), black carbon (BC) and carbon monoxide (CO)] in 200 women (main cook) by personal monitors at pre- and post-intervention. Immune function was assessed before and after intervention, in blood collected within 2 weeks of HAP measurements. Primary endpoints included reduction in HAP, lymphocyte proliferation and oxidative stress response, and alterations in T and B cell proportions. FindingsExclusive LPG use for 26 months resulted in significant reduction in PM2·5 (43.5%), BC (13%) and CO (48%) exposure in the women. For one unit decrease in BC, Treg cells and memory B cells increased by 7% and 34% respectively, in the peripheral circulation. One unit decrease in CO was significantly associated with increase in early B cells and plasmablasts by 66% and 5% respectively. For one unit decrease in BC, percent-dividing cells, proliferation and expansion indices increased by 2%, 0.4%, and 1%, respectively. InterpretationReduced personal exposure to HAP through clean fuel intervention was related to a return towards cellular immune balance.

Evaluation of Almond Harvest Dust Abatement Strategies Using an Aerial Drone Particle Monitoring System

This study demonstrates the feasibility of a mobile aerial drone particle monitoring system (DPMS) to measure and detect changes in harvest dust levels based on moderate adjustments to harvester settings. When compared to an earlier harvester, a new harvester operated at standard settings produced 35% fewer PM2.5s, 32% fewer PM10s, and 42% fewer TSPs. Increasing the ground speed had an adverse effect on dust mitigation, while reducing it by half only offered a slightly more favorable margin. The mutual effects of some meteorological factors were found to be slightly correlated with PM10 and TSP readings and caused significant variability in PM2.5 readings. The current findings show similar trends to PM reduction estimates of previous studies, with only a nominal difference of 10 to 15% points. Overall, the DPMS was found to perform well within an acceptable statistical confidence level. The use of DPMSs could reduce the logistical needs, complexity issues, and feedback times often experienced using the Federal Reference Method (FRM). Further investigation is needed to verify its robustness and to develop potential correlations with the FRM under different orchard location and management practices. At this stage, the current aerial DPMS should be considered a rapid screening tool not to replace the FRM, but rather to complement it in evaluating the feasibility of dust abatement strategies for the almond industry.

Atmospheric Oxidation Capacity and Its Impact on the Secondary Inorganic Components of PM2.5 in Recent Years in Beijing: Enlightenment for PM2.5 Pollution Control in the Future

In recent years, the concentrations of PM2.5 in urban ambient air in China have been declining; however, the strong atmospheric oxidation capacity (AOC) represents challenges to the further reduction of PM2.5 concentration and the continuous improvement of ambient air quality in China in the future, since the overall AOC is still at a high level. For this paper, based on ground observation data recorded in Beijing from 2016 to 2019, the variation in AOC was characterized according to the concentration of odd oxygen (OX = O3 + NO2). The concentrations of the primary and secondary components of PM2.5 were analyzed using empirical formulas, the correlation between AOC and the concentrations of secondary PM2.5 and the secondary inorganic components (SO42−, NO3−, NH4+, and SNA) in Beijing were explored, the impact of atmospheric photochemical reaction activity on the generation of atmospheric secondary particles was evaluated, and the impact of atmospheric oxidation variations on PM2.5 concentrations and SNA in Beijing was investigated. The results revealed that OX concentrations reached their peak in 2016 and reached their lowest point in 2019. The OX concentrations followed a descending seasonal trend of summer, spring, autumn, and winter, along with a spatial descending trend from urban observation stations to suburban stations and background stations. The degree of photochemical activity and the magnitude of the AOC have a large influence on the production of atmospheric secondary particles. When the photochemical reaction was more active and the AOC was stronger, the mass concentrations of the secondary generated PM2.5 fraction were higher and accounted for a higher proportion of the total PM2.5 mass concentrations. In the PM2.5 fraction, SNA accounted for 50.7% to 94.4% of the total mass concentrations of water-soluble inorganic ions in the field observations. Higher concentrations of the atmospheric oxidant OX in ambient air corresponded to a higher sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR), suggesting that the increase in AOC could promote the increase of PM2.5 concentration. Based on a relationship analysis of SOR, NOR, and OX, it was inferred that the relationship between OX and SOR and the relationship between OX and NOR were both nonlinear. Therefore, when establishing PM2.5 control strategies in Beijing in the future, the impact of the AOC on PM2.5 generation should be fully considered, and favorable measures should be taken to properly regulate the AOC, which would be more effective when carrying out further control measures regarding PM2.5 pollution.

Effects of window status and indoor plants on air quality, air temperature, and relative humidity: a pilot study

ABSTRACT Few empirical studies have examined the simultaneous effects of window opening and indoor plants on air characteristics. This study compared the effects of four variables, day/night, window status, plant distance, and number of plants, on air characteristics in a room at a basement via experiments. This was because plants perform photosynthesis during the day, which produces O2 and absorbs CO2, whereas they usually produce only CO2 at night. Moreover, a higher number of potted plants and a shorter distance to the plants are expected to generate greater air purification outcomes. Results included: (1) during the day and at night, the ventilation created by opening a window outperformed the transpiration from indoor plants in temperature reduction and humidity enhancement; (2) placing either three or eight potted plants indoor exhibited greater performance in reducing particulate matter (PM2.5 and PM10) and TVOC levels than opening a window; (3) a shorter distance (1.5 m) to the plant proved more effective in temperature reduction, humidity enhancement, and TVOC purification, whereas a longer distance (3.0 m) was discovered to have more effect on PM2.5 and PM10 reduction; and (4) eight potted plants significantly outperformed three in reducing temperature and increasing humidity.

Effects of the lockdown measure amid COVID-19 pandemic on outpatient department visits associated with air pollution reduction in Thailand.

We investigated the effects of COVID-19 lockdown on air quality and its consequences health and economic benefits in Thailand. The conditional Poisson regression model was applied to examine the association between air pollution and outpatient department (OPD) visits in each province and pooled the province-specific estimates using the random-effects meta-analysis to derive the national estimates. We then applied a random forest model with meteorological normalization approach to predict the concentration of air pollutants by means of business as usual during the lockdown period (April 3-May 3) in 2020 and further calculated the changes in the number of OPD visits and their consequent expenditure attributable to air pollution reduction using the obtained risk function performed earlier. The number of cardiovascular OPD visits attributed to PM10, PM2.5 and NO2 decreased by 4,414 (95% CI 982, 8,401), 4,040 (95% CI 326, 7,770), and 13,917 (95% CI 1,675, 27,278) cases, respectively, leading to reduced medical expenditure by 14,7180.21, 13,4708.31, and 46,4025.04 USD, respectively. The number of respiratory OPD visits attributed to PM10, PM2.5, NO2, and O3 reduction decreased by 2,298 (95% CI 1,223, 3,375), 2,056 (95% CI 740, 3,252), 3,326 (95% CI 542, 6,295), and 1,160 (95% CI 5,26, 1,804) cases, respectively, where the consequent medical expenditure was reduced by 76,618.48, 68,566.36, 11,0908.31, and 38,685.50 USD, respectively. Finding from this study showed that air quality during the lockdown period in Thailand was improved, contributing to the reduction of cardiovascular and respiratory OPD visits, and consequent medical service costs attributable to air pollution.

The complex role of air pollution on the association between greenness and respiratory mortality: Insight from a large cohort, 2009–2020

BackgroundAlthough emerging studies have illuminated the protective association between greenness and respiratory mortality, efforts to quantify the potentially complex role of air pollution in the causal pathway are still limited. We aimed to examine the potential roles of air pollution in the causal pathway between greenness and respiratory mortality in China. MethodsWe used data from a community-based prospective cohort of 654,115 participants in southern China (Jan 2009–Dec 2020). We evaluated the greenness exposure as a three-year moving average Normalized Difference Vegetation Index (NDVI) within the 500 m buffer around the residence. Cox proportional hazards model was applied to estimate the association between greenness and respiratory mortality. Causal mediation analysis combined with a four-way dimensional decomposition method was utilized to simultaneously quantify the interaction and mediation role of air pollution including PM2.5, PM10, or NO2 on the greenness-respiratory mortality relationship. FindingsWe observed 6954 respiratory deaths during 12 years of follow-up. Increasing NDVI level from the lowest to the highest quartile is associated with a 19 % (95%CI: 13–25 %) reduction in the respiratory mortality risk. For the total protective effect, the proportion attributable to the overall negative interaction between greenness and air pollution (PM2.5, PM10, or NO2) was 2.2 % (1.7–3.2 %), 3.5 % (0.4–3.7 %), or 25.0 % (22.8–27.1 %), respectively. Simultaneously, we estimated 25.5 % (20.1–32.0 %), 49.5 % (32.5–71.9 %), or 1.0 % (0.8–1.2 %) of the total protective association was mediated through a reduction in PM2.5, PM10, or NO2, respectively. InterpretationIncreased greenness exposure mitigated respiratory mortality through both the antagonistic interaction and mediation pathway of air pollution (PM2.5, PM10, or NO2).

Drivers of alleviated PM2.5 and O3 concentrations in China from 2013 to 2020

Since 2013, the Chinese Government implemented “Clean Air Action” Phase I (2013–2017) and Phase II (2018–2020) consecutively to improve air quality. However, it remains unclear how these policies have impacted air quality since most studies merely focus on Phase I. In this study, we applied the Community Multiscale Air Quality (CMAQ) model to investigate variations of air quality in China during “Clean Air Action” Phases I and Phase II (2013–2020). Results show that PM2.5 is significantly reduced (-40%) across China except in summer. O3 concentration also decreases, but a 3% increase is found in the Beijing-Tianjin-Hebei (BTH) region. Emission changes play a dominant role in the reduction of PM2.5 (over 95%). The contributions from meteorology and emissions to O3 reduction are 46% and 54%, respectively. Our results suggest that a more effective emission abatement strategy should be formulated, aiming to control O3 and PM2.5 synergistically.

Assessing the Environmental and Health Co-benefits of Accelerated Energy Transition and Industrial Restructuring: A Case Study of the BTHS Region

The Beijing-Tianjin-Hebei-Shandong Region (BTHS Region) is a crucial area for China to achieve synergy between pollution reduction and carbon emissions reduction. The demand for coordinated emissions reduction through source control measures such as energy transition and industrial restructuring are becoming increasingly necessary owing to the limited emissions reductions potential of end-of-pipe control measures. An assessment of the emissions reductions potential through strengthening the end-of-pipe control in the BTHS Region, as well as the environmental and health co-benefits from accelerated energy transition and industrial restructuring, was conducted using scenario simulation analysis based on the REACH model. The results showed that the rapid implementation of the best available end-of-pipe control technologies in the BTHS Region would result in 3.3 μg·m-3 reduction in PM2.5 concentration in 2035, but this would not be sufficient to achieve the PM2.5 concentration control targets. Accelerating the energy transition and the industrial restructuring are necessary for the BTHS Region to achieve air quality standards, which would reduce the PM2.5 concentrations by 6.3 μg·m-3 in 2035. The environmental and health co-benefits brought by the accelerated transition could partially or entirely offset the additional socio-economic cost (compared to that of the current policy efforts) of approximately 0.9%-2.5% of the total regional GDP in achieving the PM2.5 concentration control target paid by the four provinces.

Spatial and sector-specific contributions of emissions to ambient air pollution and mortality in European cities: a health impact assessment

Ambient air pollution is a major risk to health and wellbeing in European cities. We aimed to estimate spatial and sector-specific contributions of emissions to ambient air pollution and evaluate the effects of source-specific reductions in pollutants on mortality in European cities to support targeted source-specific actions to address air pollution and promote population health. We conducted a health impact assessment of data from 2015 for 857 European cities to estimate source contributions to annual PM2·5 and NO2 concentrations using the Screening for High Emission Reduction Potentials for Air quality tool. We evaluated contributions from transport, industry, energy, residential, agriculture, shipping, and aviation, other, natural, and external sources. For each city and sector, three spatial levels were considered: contributions from the same city, the rest of the country, and transboundary. Mortality effects were estimated for adult populations (ie, ≥20 years) following standard comparative risk assessment methods to calculate the annual mortality preventable on spatial and sector-specific reductions in PM2·5 and NO2. We observed strong variability in spatial and sectoral contributions among European cities. For PM2·5, the main contributors to mortality were the residential (mean contribution of 22·7% [SD 10·2]) and agricultural (18·0% [7·7]) sectors, followed by industry (13·8% [6·0]), transport (13·5% [5·8]), energy (10·0% [6·4]), and shipping (5·5% [5·7]). For NO2, the main contributor to mortality was transport (48·5% [SD 15·2]), with additional contributions from industry (15·0% [10·8]), energy (14·7% [12·9]), residential (10·3% [5·0]), and shipping (9·7% [12·7]). The mean city contribution to its own air pollution mortality was 13·5% (SD 9·9) for PM2·5 and 34·4% (19·6) for NO2, and contribution increased among cities of largest area (22·3% [12·2] for PM2·5 and 52·2% [19·4] for NO2) and among European capitals (29·9% [12·5] for PM2·5 and 62·7% [14·7] for NO2). We estimated source-specific air pollution health effects at the city level. Our results show strong variability, emphasising the need for local policies and coordinated actions that consider city-level specificities in source contributions. Spanish Ministry of Science and Innovation, State Research Agency, Generalitat de Catalunya, Centro de Investigación Biomédica en red Epidemiología y Salud Pública, and Urban Burden of Disease Estimation for Policy Making 2023-2026 Horizon Europe project.

Prediction of daily PM2.5 and ozone based on high-density weather stations in China: Nonlinear effects of meteorology, human and ecosystem health risks

In recent decade, despite the implementation of strict emission reductions, PM2.5 and surface ozone (O3) in China are still at high pollution level. In this study, based on observations at air quality stations (∼1500 mainly in urban region), daily PM2.5 and MDA8 (the daily maximum 8 h average) O3 concentrations in high-density and uniform meteorological sites (∼2000) over China during 2017–2019 were retrieved using generalized additive models (GAMs) for different regions on a seasonal scale, in order to establish 0.1° gridded datasets and investigate their spatiotemporal characteristics, nonlinear effects of meteorology, and ambient air pollution-attributable health risks on a regional scale. This model can provide high accuracy in the estimation of daily PM2.5 (O3) in 2018 with overall cross-validation R2 and RMSE of 0.81 (0.80) and 12.73 (17.63) μg/m3 and predictive capability in 2017 and 2019 with R2 of 0.67 (0.70) for PM2.5 (O3). Temperature, relative humidity and visibility are three main meteorological factors driving PM2.5 (O3) response. PM2.5 generally exhibits an exponential decrease with increasing visibility and an increase with increasing relative humidity, while is suppressed at the thresholds of 60% and 70%. For O3, in northern China, positive response of temperature is more important and O3 suppression exists at 36 °C ∼ 41.5 °C, whereas negative response of relative humidity is dominating in southern China. Overall, annual averaged PM2.5 (O3) values across China reduced (increased) by 18.7% (11.2%) between 2017 and 2019, with the highest concentrations and variation in North China. These variations contributed to a 14.9% reduction in PM2.5 attributed premature deaths, but a 10.4% increase in O3 exposure related deaths. Generally, central-eastern China still exists greater health risk with per capita premature mortality ranging from 0.80‰ to 1.19‰ for PM2.5 and 1.91‰ to 2.60‰ for O3. Additionally, O3 vegetation damages demonstrate a decline (increase) by 1.3% (21.7%) in North China with higher O3 pollution (southern China with slight pollution) between 2017 and 2019. These findings highlight the essentiality for the synergistic control of PM2.5 and O3 based on regional differences in China.

PCCI-DI Combustion Simulation for Significant Reduction of NOX and PM for GENSET Engine

Improvements in engine combustion are required due to the stringent pollution norms. This can be achieved either by making improvements in the combustion or by equipping after-treatment devices to control engine emission levels. PCCI is one of the popular techniques used to enhance the combustion. In this work, Diesel-RK software is used for the simulation. The main and pre-injection timings are altered to give the benefits in power and emissions. Based on a literature survey, the fourth and fifth modes are finalized for PCCI combustion simulation. The amount of total fuel injected was kept the same to compare the performances in DI and PCCI modes. The simulation results show the reduction in soot (PM) and NOx simultaneously with the help of PCCI concept at lower BMEP levels. The results show a decrease in PM by up to 26%, a reduction in NOx by up to 30% and an increase in power by 2%.

Assessment of Emission Reduction Effect of Major Air Pollution Control Measures on PM2.5 Concentrations During 13th Five-Year Period in Tianjin

The emission reduction effect of major air pollution control measures on PM2.5 concentrations was assessed using air quality simulations based on the calculation data of emission reductions from different air pollution control measures and the high spatiotemporal resolution online monitoring data of PM2.5 during the 13th Five-Year Period in Tianjin. The results showed that the total emission reductions of SO2, NOx, VOCs, and PM2.5 from 2015 to 2020 were 4.77×104, 6.20×104, 5.37×104, and 3.53×104 t, respectively. SO2 emission reduction was mainly due to the prevention of process pollution, loose coal combustion, and thermal power. NOx emission reduction was mainly due to the prevention of process pollution, thermal power, and steel industry. VOCs emission reduction was mainly due to prevention of process pollution. PM2.5 emission reduction was mainly due to the prevention of process pollution, loose coal combustion, and the steel industry. The concentrations, pollution days, and heavy pollution days of PM2.5 decreased significantly from 2015 to 2020 by 31.4%, 51.2%, and 60.0% compared to those in 2015, respectively. The concentrations and pollution days of PM2.5 decreased slowly in the later stage (from 2018 to 2020)as compared with those in the early stage (from 2015 to 2017), and the days of heavy pollution remained for approximately 10 days. The results of air quality simulations showed that meteorological conditions contributed one-third to the reduction in PM2.5 concentrations, and the emission reductions of major air pollution control measures contributed two-thirds to the reduction in PM2.5 concentrations. For all air pollution control measures from 2015 to 2020, PM2.5 concentrations were reduced by the prevention of process pollution, loose coal combustion, the steel industry, and thermal power by 2.66, 2.18, 1.70, and 0.51 μg·m-3, respectively, accounting for 18.3%, 15.0%, 11.7%, and 3.5% of PM2.5 concentration reductions. In order to promote the continuous improvement in PM2.5 concentrations during the 14th Five-Year Plan period, under the total coal consumption control and the goal of "peaking carbon dioxide emissions and achieving carbon neutrality," Tianjin should continue to optimize and adjust the coal structure and further promote the coal consumption to the power industry with an advanced pollution control level. At the same time, it is necessary to further improve the emission performance of industrial sources in the whole process, taking environmental capacity as the constraint; design the technical route for industrial optimization, adjustment, transformation, and upgrading; and optimize the allocation of environmental capacity resources. Additionally, the orderly development model for key industries with limited environmental capacity should be proposed, and clean upgrading, transformation, and green development should be guided for enterprises.

Mitigation of urban particulate pollution using lightweight green roof system

As the global population becomes more concentrated in urban environments, higher numbers of people will be exposed to urban air pollution. The environmental and human health benefits of green roofs are widely recognized. The aim of this paper is to promote green roofs as an effective passive technique for pollution mitigation and adaptation to climate change. During the heating season, the ambient concentrations of PM1, PM2.5, and PM10 were measured above a green roof and a reference roof on a school building, located in New Belgrade, the second-most populous municipality and business center of Serbia’s largest city. The percent reduction of PM10, PM2.5 and PM1, in January 2020, above the green roof compared to the reference roof was 7%, 16.6%, and 17.6%, respectively. The results show that lightweight green roof improve air quality in terms of PM concentrations for all months considered. In this paper, correlation analysis and the use of Pearson’s coefficient were used in the process of analysis to determine the relationship between PM10, PM2.5, PM1, and ambient parameters: relative humidity, ambient temperature, and wind speed. It was found that the statistical correlation expressed by the Pearson coefficient between all PM particles and wind speed was statistically significant in all observed months except September. Also, the degree of significance of the correlation between PM particles and humidity and temperature of ambient air varies by month.

The energy conservation and emission reduction potentials in China's iron and steel industry: Considering the uncertainty factor

Energy conservation and emission reduction in China's iron and steel industry are crucial for mitigating its environmental pressures. However, uncertainties raise significant management risks when setting energy conservation and emission reduction pathways. Therefore, this paper explores the energy conservation and emission reduction potential in China's iron and steel industry. A 10,000-time Latin hypercube sampling is conducted to simulate the distribution of five types of uncertain factors. In addition, this study uses a Sobol’ sensitivity analysis method to recognize the most sensitive factor, and, in specific, analyzes the cost-effectiveness of the technologies via conservation supply curve. The results show that: (1) The uncertainty factors lead to significant fluctuate to the results. In particular, energy conservation will fluctuate by 18.24–40.77%, carbon mitigation by 28.96–55.34%, and SO2, NOx and PM mitigation effects will fluctuate by 48.32–79.53%, 22.12–51.77% and 23.92–50.03%, respectively. (2) Structure and equipment parameters are more the most sensitive to energy conservation and carbon mitigation targets, whose Sobol’ indices are beyond 0.45. End-of-pipe treatment technologies are more the most sensitive to SO2 and PM reduction targets with Sobol’ indices above 0.9. Penetration rates and equipment parameters are more the most sensitive to economic cost targets above 0.8. (3) In 2035, 33 energy conservation technologies and 34 emission reduction technologies will be cost-effective, and they can achieve 69.05–70.14% of energy conservation and 79.03–81.58% of emission reduction potentials, respectively. Based on these findings, this study proposes policy recommendations such as changing the raw material/product structure, upgrading equipment, cooperating actively, and introducing economic incentives and guidelines for technology application.

Meteorological influences on co-occurrence of O3 and PM2.5 pollution and implication for emission reductions in Beijing-Tianjin-Hebei

Co-occurrence of surface ozone (O3) and fine particulate matter (PM2.5) pollution (CP) was frequently observed in Beijing-Tianjin-Hebei (BTH). More than 50% of CP days occurred during April–May in BTH, and the CP days reached up to 11 in two months of 2018. The PM2.5 or O3 concentration associated with CP was lower than but close to that in O3 and PM2.5 pollution, indicating compound harms during CP days with double-high concentrations of PM2.5 and O3. CP days were significantly facilitated by joint effects of the Rossby wave train that consisted of two centers associated with the Scandinavia pattern and one center over North China as well as a hot, wet, and stagnant environmental condition in BTH. After 2018, the number of CP days decreased sharply while the meteorological conditions did not change significantly. Therefore, changes in meteorological conditions did not really contribute to the decline of CP days in 2019 and 2020. This implies that the reduction of PM2.5 emission has resulted in a reduction of CP days (about 11 days in 2019 and 2020). The differences in atmospheric conditions revealed here were helpful to forecast the types of air pollution on a daily to weekly time scale. The reduction in PM2.5 emission was the main driving factor behind the absence of CP days in 2020, but the control of surface O3 must be stricter and deeper.

Can transportation network companies improve urban air quality?

The environmental impacts of transportation network companies (TNCs) have been under intense debate with conflicting claims. However, there are limited empirical studies that quantify TNCs’ environmental impacts. This study examines the impact of TNCs on urban air quality in 388 metropolitan statistical areas (MSAs) in the U.S. over the period from 2010 to 2018. Based on difference-in-differences and yearly regression models, we generate three major findings: (1) The entry of TNCs has a positive impact on the overall urban air quality measured by AQI; (2) despite the positive impact on the overall air quality, TNC entry increases CO and NO2 pollution; and (3) TNC entry reduces PM10 pollution but has no statistically significant impact on PM2.5 pollution, and the effect on PM10 reduction takes 2 years to appear. The findings provide useful insights into the management and design of shared mobility and urban transport systems.