Showing papers on "Particulates published in 2021"

Abating ammonia is more cost-effective than nitrogen oxides for mitigating PM 2.5 air pollution

Abstract: Fine particulate matter (PM2.5, particles with a mass median aerodynamic diameter of less than 2.5 micrometers) in the atmosphere is associated with severe negative impacts on human health, and the gases sulfur dioxide, nitrogen oxides, and ammonia are the main PM2.5 precursors. However, their contribution to global health impacts has not yet been analyzed. Here, we show that nitrogen accounted for 39% of global PM2.5 exposure in 2013, increasing from 30% in 1990 with rising reactive nitrogen emissions and successful controls on sulfur dioxide. Nitrogen emissions to air caused an estimated 23.3 million years of life lost in 2013, corresponding to an annual welfare loss of 420 billion United States dollars for premature death. The marginal abatement cost of ammonia emission is only 10% that of nitrogen oxides emission globally, highlighting the priority for ammonia reduction.

Control of particulate nitrate air pollution in China

Abstract: The concentration of fine particulate matter (PM2.5) across China has decreased by 30–50% over the period 2013–2018 due to stringent emission controls. However, the nitrate component of PM2.5 has not responded effectively to decreasing emissions of nitrogen oxides and has actually increased during winter haze pollution events in the North China Plain. Here, we show that the GEOS-Chem atmospheric chemistry model successfully simulates the nitrate concentrations and trends. We find that winter mean nitrate would have increased over 2013–2018 were it not for favourable meteorology. The principal cause of this nitrate increase is weaker deposition. The fraction of total inorganic nitrate as particulate nitrate instead of gaseous nitric acid over the North China Plain in winter increased from 90% in 2013 to 98% in 2017, as emissions of nitrogen oxides and sulfur dioxide decreased while ammonia emissions remained high. This small increase in the particulate fraction greatly slows down deposition of total inorganic nitrate and hence drives the particulate nitrate increase. Our results suggest that decreasing ammonia emissions would decrease particulate nitrate by driving faster deposition of total inorganic nitrate. Decreasing nitrogen oxide emissions is less effective because it drives faster oxidation of nitrogen oxides and slower deposition of total inorganic nitrate. Reduction of ammonia emissions may be effective in reducing the nitrate component of fine particulate matter air pollution across the North China Plain, according to the simulation of nitrate trends using the GEOS-Chem atmospheric chemistry model.

Enhanced aerosol particle growth sustained by high continental chlorine emission in India

Abstract: Many cities in India experience severe deterioration of air quality in winter. Particulate matter is a key atmospheric pollutant that impacts millions of people. In particular, the high mass concentration of particulate matter reduces visibility, which has severely damaged the economy and endangered human lives. But the underlying chemical mechanisms and physical processes responsible for initiating haze and fog formation remain poorly understood. Here we present the measurement results of chemical composition of particulate matter in Delhi and Chennai. We find persistently high chloride in Delhi and episodically high chloride in Chennai. These measurements, combined with thermodynamic modelling, suggest that in the presence of excess ammonia in Delhi, high local emission of hydrochloric acid partitions into aerosol water. The highly water-absorbing and soluble chloride in the aqueous phase substantially enhances aerosol water uptake through co-condensation, which sustains particle growth, leading to haze and fog formation. We therefore suggest that the high local concentration of gas-phase hydrochloric acid, possibly emitted from plastic-contained waste burning and industry, causes some 50% of the reduced visibility. Our work implies that identifying and regulating gaseous hydrochloric acid emissions could be critical to improve visibility and human health in India. Half of the reduced visibility due to haze formation in cities in India is attributed to local emission of gas-phase hydrochloric acid from waste-burning and industry, according to measurements of particulate matter and thermodynamic modelling.

Sulfate formation is dominated by manganese-catalyzed oxidation of SO2 on aerosol surfaces during haze events.

Abstract: The formation mechanism of aerosol sulfate during wintertime haze events in China is still largely unknown. As companions, SO2 and transition metals are mainly emitted from coal combustion. Here, we argue that the transition metal-catalyzed oxidation of SO2 on aerosol surfaces could be the dominant sulfate formation pathway and investigate this hypothesis by integrating chamber experiments, numerical simulations and in-field observations. Our analysis shows that the contribution of the manganese-catalyzed oxidation of SO2 on aerosol surfaces is approximately one to two orders of magnitude larger than previously known routes, and contributes 69.2% ± 5.0% of the particulate sulfur production during haze events. This formation pathway could explain the missing source of sulfate and improve the understanding of atmospheric chemistry and climate change. Sulfate aerosols are an important component of wintertime haze events in China, but their production mechanisms are not well known. Here, the authors show that transition metal-catalyzed oxidation of SO2 on aerosol surfaces could be the dominant sulfate formation pathway in Northern China.

An overview of nitrogen oxides emissions from biomass combustion for domestic heat production

Abstract: In order to fulfill the European Union's climate and energy goals, the heating and cooling sector must cut its use of fossil fuels. Solid biomass can constitute an alternative to fossil fuels as a renewable and carbon-neutral source of energy but there are some aspects to biomass combustion in small-scale domestic appliances that can compromise the environmental sustainability of this renewable energy source in terms of burden on air quality. The priority pollutants in this respect are particulate matter and nitrogen oxides. While particulate matter emissions are often discussed, nitrogen oxides emissions from domestic heating appliances are relatively less in the center of attention. The aim of the present study is to review the literature regarding the nitrogen oxides emissions from this emission source discussing the main formation mechanisms and the state-of-the-art control techniques, as well as the influence of fuel composition (especially fuel bound nitrogen), heating appliance type and operating conditions with the help of the gathered experimental emission factors data. The review crosslinks several aspects usually treated separately in scientific papers (e.g., only laboratory tests with basic theory or only field tests on emission levels etc.), providing thus a quick reference tool to the state-of-the-art knowledge on this topic.

Sources, characteristics, toxicity, and control of ultrafine particles: An overview

Abstract: Air pollution by particulate matter (PM) is one of the main threats to human health, particularly in large cities where pollution levels are continually exceeded. According to their source of emission, geography, and local meteorology, the pollutant particles vary in size and composition. These particles are conditioned to the aerodynamic diameter and thus classified as coarse (2.5–10 μm), fine (0.1–2.5 μm), and ultrafine (

Rapid increase in summer surface ozone over the North China Plain during 2013–2019: a side effect of particulate matter reduction control?

Abstract: . While the elevated ambient levels of particulate matters with aerodynamic diameter of 2.5 micrometers or less (PM2.5) are alleviated largely with the implementation of effective emission control measures, an opposite trend with a rapid increase is seen in surface ozone (O3) in the North China Plain (NCP) region over the past several years. It is critical to determine the real culprit causing such a large increase in surface O3. In this study, seven-year surface observations and satellite retrieval data are analyzed to determine the long-term change in surface O3 as well as driving factors. Results indicate that anthropogenic emission control strategies and changes in aerosol concentrations as well as aerosol optical properties such as single-scattering albedo (SSA) are the most important factors driving such a large increase in surface O3. Numerical simulations with National Center for Atmospheric Research (NCAR) Master Mechanism (MM) model suggest that reduction of O3 precursor emissions and aerosol radiative effect accounted for 45 % and 23 % of the total change in surface O3 in summertime during 2013–2019, respectively. Planetary boundary layer (PBL) height with an increase of 0.21 km and surface air temperature with an increase of 2.1 °C contributed 18 % and 12 % to the total change in surface O3, respectively. The combined effect of these factor was responsible for the rest change. Decrease in SSA or strengthened absorption property of aerosols may offset the impact of AOD reduction on surface O3 substantially. While the MM model enables quantification of individual factor's percentage contributions, it requires further refinement with aerosol chemistry included in the future investigation. The study indicates an important role of aerosol radiative effect in development of more effective emission control strategies on reduction of ambient levels of O3 as well as alleviation of national air quality standard exceedance events.

Ambient Air Pollution and Atherosclerosis: Insights Into Dose, Time, and Mechanisms.

Abstract: Ambient air pollution due to particulate matter ≤2.5 μ is the leading environmental risk factor contributing to global mortality, with a preponderant majority of these deaths attributable to athero...

Time Series Analysis and Forecasting of Air Pollution Particulate Matter (PM 2.5 ): An SARIMA and Factor Analysis Approach

Abstract: Current development of Pakistan’s economy, transportation and industry with the improvement of urbanization, environmental pollution problems have gradually become prominent, but this is contrary to people’s vision of pursuing a high-quality life. Now the problem of haze, photochemical problems in the air, and global warming is already a key issue of global concern. This is focused on the ambient air quality of Lahore city of Pakistan. The study reveals that the particulate matter in the Lahore season (PM2.5, PM10) exceeds Pakistan’s National Environmental Quality Standards (NEQS). Correlation study suggests the positive correlation between the particulate matter and other mass concentration particles like Ozone (O3), Nitrogen Oxide (NO), Sulphur Dioxide (SO2). Higher values of CO/NO suggest that mobile sources are one of the major factors of this increase in NO. Further estimation of backward trajectory is done by the Hybrid-Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model which provides the path of those particles in the last year period and the source of origin is from Afghanistan. This study provides in depth analysis of all factors of air pollutants by correlation between those factors. Prediction of future concentration of PM2.5 is predicted using the Seasonal Autoregressive Integrated Moving Average (SARIMA) model which gives the increasing value of PM2.5 in next year and provides the lowest and highest predicts (more than $100~\mu \text{g}/\text{m}^{3}$ ).

Particulate matter emission control from small residential boilers after biomass combustion. A review

Abstract: In this paper, lab and commercial constructions of electrostatic precipitators used for the removal of fly ash particles from small residential boilers have been reviewed. The presented solutions were evaluated in terms of removal efficiency, exploitation conditions or expected maintenance costs. Boilers used for household heating are the main sources of air contamination by particulate matter during winter seasons in many countries. The collection efficiency of such devices should be higher than 95% to comply with the ECODESIGN emission limit, and the emission level for biomass

Chemical characterization and source apportionment of PM1 and PM2.5 in Tianjin, China: Impacts of biomass burning and primary biogenic sources.

Abstract: The submicron particulate matter (PM1) and fine particulate matter (PM2.5) are very important due to their greater adverse impacts on the natural environment and human health. In this study, the daily PM1 and PM2.5 samples were collected during early summer 2018 at a sub-urban site in the urban-industrial port city of Tianjin, China. The collected samples were analyzed for the carbonaceous fractions, inorganic ions, elemental species, and specific marker sugar species. The chemical characterization of PM1 and PM2.5 was based on their concentrations, compositions, and characteristic ratios (PM1/PM2.5, AE/CE, NO3−/SO42−, OC/EC, SOC/OC, OM/TCA, K+/EC, levoglucosan/K+, V/Cu, and V/Ni). The average concentrations of PM1 and PM2.5 were 32.4 µg/m3 and 53.3 µg/m3, and PM1 constituted 63% of PM2.5 on average. The source apportionment of PM1 and PM2.5 by positive matrix factorization (PMF) model indicated the main sources of secondary aerosols (25% and 34%), biomass burning (17% and 20%), traffic emission (20% and 14%), and coal combustion (17% and 14%). The biomass burning factor involved agricultural fertilization and waste incineration. The biomass burning and primary biogenic contributions were determined by specific marker sugar species. The anthropogenic sources (combustion, secondary particle formation, etc) contributed significantly to PM1 and PM2.5, and the natural sources were more evident in PM2.5. This work significantly contributes to the chemical characterization and source apportionment of PM1 and PM2.5 in near-port cities influenced by the diverse sources.

Impact of lower and higher alcohols on the physicochemical properties of particulate matter from diesel engines: A review

Abstract: The literature reveals that fossil fuels will continue to be the main energy source for transportation fleets up to 2050, despite their non-renewability and the emissions of pollutants resulting from their use. Until the full adoption of non-fossil and zero-emission vehicles (e.g., electric vehicles), the application of renewable liquid fuels could be the best choice due to the latter's positive effects such as reduced consumption of fossil fuels and reduced emissions of pollutants. Alcohols, among others, have been widely tested as alternative fuels in diesel engines, however, there is no comprehensive information about their impacts on particulate matter (PM) which has a direct influence on human health, the environment, and emission catalyst's efficiency. This review comprehensively explores the impact of lower/higher alcohols, from methanol to decanol, in dual-fuel mode on the PM physicochemical properties emitted from diesel engines under different alcohol ratios and operating conditions. It is observed that alcohols change the PM physical properties by reducing primary particle size/number, radius of gyration, fractal dimension, and fringe length and increasing fringe separation distance and tortuosity compared to those of diesel PM. Regarding the chemical properties, alcohols reduce polycyclic aromatic hydrocarbons, benzo[a]pyrene equivalent, organic carbon (OC), elemental carbon (EC), ions, and soot ignition temperature and increase OC/EC ratio and soot oxidation reactivity. Thus, each 10% of alcohol, by volume, has the potential to reduce PM mass, number, and size by about 17, 20, and 10%, while lower alcohols and blended mode have more impact than higher alcohols and fumigation mode, respectively.

Contribution of tailpipe and non-tailpipe traffic sources to quasi-ultrafine, fine and coarse particulate matter in southern California.

Abstract: Exposure to traffic-related air pollution (TRAP) in the near-roadway environment is associated with multiple adverse health effects. To characterize the relative contribution of tailpipe and non-ta...

Emission characteristics of condensable particulate matter and sulfur trioxide from coal-fired power plants

Abstract: Non-criteria air pollutants, namely, sulfur trioxide (SO3) and condensable particulate matter (CPM), are attracted more attention due to the non-negligible emission. In this work, the migration and emission characteristics of SO3 and CPM were investigated in two typical coal-fired power plants using the isopropanol absorption method and the dry impinger method, respectively. One of the power plants was equipped with two-stage wet flue gas desulfurization (WFGD) and the other one was self-generation power plant using Zhundong coal equipped with one-stage WFGD. The mass concentrations of SO3 and CPM were measured at the inlet and outlet of the air pollution control devices. To further understand the removal characteristics, the chemical compositions in organic and inorganic fractions of CPM were analyzed. Based on the measurement data, the emission factors of CPM and SO3 were calculated. The final emissions of SO3 range from 2.16 to 2.29 mg•Nm−3 and the emission factor is 0.024–0.040 kg/(t of coal). The stack emissions of filterable particulate matter all meet the ultra-low emission standard and are less than 5 mg•Nm−3. However, CPM emissions all exceed 10 mg•Nm−3 and account for more than 85% in total particulate matter. CPM concentrations are notable and the emissions should not be ignored. In both power plants, WFGD and wet electrostatic precipitator can reduce the emission of organic fraction in CPM; while one-stage WFGD has negative effect on the mitigation of inorganic fraction in CPM with the concentrations of water-soluble ions NH4+, SO42- and Cl− increasing by 41.37%, 52.22% and 91.73%, respectively.