Showing papers on "Particulates published in 2018"

Short-term elevation of fine particulate matter air pollution and acute lower respiratory infection

Abstract: Rationale: Nearly 60% of U.S. children live in counties with particulate matter less than or equal to 2.5 μm in aerodynamic diameter (PM2.5) concentrations above air quality standards. Understandin...

Washable Multilayer Triboelectric Air Filter for Efficient Particulate Matter PM2.5 Removal

Abstract: Efficient removal of particulate matter (PM) is the major goal for various air cleaning technologies due to its huge impact on human health. Here, a washable high-efficiency triboelectric air filter (TAF) that can be used multiple times is presented. The TAF consists of five layers of the polytetrafluoroethylene (PTFE) and nylon fabrics. Compared with traditional electrostatic precipitator, which requires a high-voltage power supply, the TAF can be charged by simply rubbing the PTFE and nylon fabrics against each other. The electrical properties of the TAF are evaluated through the periodic contacting–separating of the PTFE and nylon fabrics using a linear motor, and an open-circuit voltage of 190 V is achieved. After charging, the TAF has a removal efficiency of 84.7% for PM0.5, 96.0% for PM2.5, which are 3.22 and 1.39 times as large as the uncharged one. Most importantly, after washing several times, the removal efficiency of the TAF maintains almost the same, while the commercial face mask drops to 70% of its original efficiency. Furthermore, the removal efficiency of the PM2.5 is very stable under high relative humidity. Therefore, the TAF is promising for fabricating a reusable and high-efficiency face mask.

Residential energy use emissions dominate health impacts from exposure to ambient particulate matter in India

Abstract: Exposure to ambient fine particulate matter (PM25) is a leading contributor to diseases in India Previous studies analysing emission source attributions were restricted by coarse model resolution and limited PM25 observations We use a regional model informed by new observations to make the first high-resolution study of the sector-specific disease burden from ambient PM25 exposure in India Observed annual mean PM25 concentrations exceed 100 μg m−3 and are well simulated by the model We calculate that the emissions from residential energy use dominate (52%) population-weighted annual mean PM25 concentrations, and are attributed to 511,000 (95UI: 340,000–697,000) premature mortalities annually However, removing residential energy use emissions would avert only 256,000 (95UI: 162,000–340,000), due to the non-linear exposure–response relationship causing health effects to saturate at high PM25 concentrations Consequently, large reductions in emissions will be required to reduce the health burden from ambient PM25 exposure in India

Nitrate-driven urban haze pollution during summertime over the North China Plain

Abstract: . Compared to the severe winter haze episodes in the North China Plain (NCP), haze pollution during summertime has drawn little public attention. In this study, we present the highly time-resolved chemical composition of submicron particles (PM 1) measured in Beijing and Xinxiang in the NCP region during summertime to evaluate the driving factors of aerosol pollution. During the campaign periods (30 June to 27 July 2015, for Beijing and 8 to 25 June 2017, for Xinxiang), the average PM 1 concentrations were 35.0 and 64.2 µ g m −3 in Beijing and Xinxiang. Pollution episodes characterized with largely enhanced nitrate concentrations were observed at both sites. In contrast to the slightly decreased mass fractions of sulfate, semivolatile oxygenated organic aerosol (SV-OOA), and low-volatility oxygenated organic aerosol (LV-OOA) in PM 1 , nitrate displayed a significantly enhanced contribution with the aggravation of aerosol pollution, highlighting the importance of nitrate formation as the driving force of haze evolution in summer. Rapid nitrate production mainly occurred after midnight, with a higher formation rate than that of sulfate, SV-OOA, or LV-OOA. Based on observation measurements and thermodynamic modeling, high ammonia emissions in the NCP region favored the high nitrate production in summer. Nighttime nitrate formation through heterogeneous hydrolysis of dinitrogen pentoxide (N 2 O 5) enhanced with the development of haze pollution. In addition, air masses from surrounding polluted areas during haze episodes led to more nitrate production. Finally, atmospheric particulate nitrate data acquired by mass spectrometric techniques from various field campaigns in Asia, Europe, and North America uncovered a higher concentration and higher fraction of nitrate present in China. Although measurements in Beijing during different years demonstrate a decline in the nitrate concentration in recent years, the nitrate contribution in PM 1 still remains high. To effectively alleviate particulate matter pollution in summer, our results suggest an urgent need to initiate ammonia emission control measures and further reduce nitrogen oxide emissions over the NCP region.

Effectiveness of face masks used to protect Beijing residents against particulate air pollution.

Abstract: Objectives Many residents in Beijing use disposable face masks in an attempt to protect their health from high particulate matter (PM) concentrations. Retail masks may be certified to local or international standards, but their real-life performance may not confer the exposure reduction potential that is marketed. This study aimed to evaluate the effectiveness of a range of face masks that are commercially available in China. Methods Nine masks claiming protection against fine PM (PM 2.5 ) were purchased from consumer outlets in Beijing. The masks’ filtration efficiency was tested by drawing airborne diesel exhaust through a section of the material and measuring the PM 2.5 and black carbon (BC) concentrations upstream and downstream of the filtering medium. Four masks were selected for testing on volunteers. Volunteers were exposed to diesel exhaust inside an experimental chamber while performing sedentary tasks and active tasks. BC concentrations were continuously monitored inside and outside the mask. Results The mean per cent penetration for each mask material ranged from 0.26% to 29%, depending on the flow rate and mask material. In the volunteer tests, the average total inward leakage (TIL) of BC ranged from 3% to 68% in the sedentary tests and from 7% to 66% in the active tests. Only one mask type tested showed an average TIL of less than 10%, under both test conditions. Conclusions Many commercially available face masks may not provide adequate protection, primarily due to poor facial fit. Our results indicate that further attention should be given to mask design and providing evidence-based guidance to consumers.

Trace Metals in Soot and PM2.5 from Heavy-Fuel-Oil Combustion in a Marine Engine.

Abstract: Heavy fuel oil (HFO) particulate matter (PM) emitted by marine engines is known to contain toxic heavy metals, including vanadium (V) and nickel (Ni). The toxicity of such metals will depend on the their chemical state, size distribution, and mixing state. Using online soot-particle aerosol mass spectrometry (SP-AMS), we quantified the mass of five metals (V, Ni, Fe, Na, and Ba) in HFO-PM soot particles produced by a marine diesel research engine. The in-soot metal concentrations were compared to in-PM2.5 measurements by inductively coupled plasma-optical emission spectroscopy (ICP-OES). We found that <3% of total PM2.5 metals was associated with soot particles, which may still be sufficient to influence in-cylinder soot burnout rates. Since these metals were most likely present as oxides, whereas studies on lower-temperature boilers report a predominance of sulfates, this result implies that the toxicity of HFO PM depends on its combustion conditions. Finally, we observed a 4-to-25-fold enhancement in th...

Source-Specific Health Risk Analysis on Particulate Trace Elements: Coal Combustion and Traffic Emission As Major Contributors in Wintertime Beijing

Abstract: Source apportionment studies of particulate matter (PM) link chemical composition to emission sources, while health risk analyses link health outcomes and chemical composition There are limited studies to link emission sources and health risks from ambient measurements We show such an attempt for particulate trace elements Elements in PM25 were measured in wintertime Beijing, and the total concentrations of 14 trace elements were 13-73 times higher during severe pollution days than during low pollution days Fe, Zn, and Pb were the most abundant elements independent of the PM pollution levels Chemical fractionation shows that Pb, Mn, Cd, As, Sr, Co, V, Cu, and Ni were present mainly in the bioavailable fraction Positive matrix factorization was used to resolve the sources of particulate trace elements into dust, oil combustion, coal combustion, and traffic-related emissions Traffic-related emission contributed 65% of total mass of the measured elements during low pollution days However, coal combustion dominated (58%) during severe pollution days By combining element-specific health risk analyses and source apportionment results, we conclude that traffic-related emission dominates the health risks by particulate trace elements during low pollution days, while coal combustion becomes equally or even more important during moderate and severe pollution days

Global Sources of Fine Particulate Matter: Interpretation of PM2.5 Chemical Composition Observed by SPARTAN using a Global Chemical Transport Model

Abstract: Exposure to ambient fine particulate matter (PM2.5) is a leading risk factor for the global burden of disease. However, uncertainty remains about PM2.5 sources. We use a global chemical transport model (GEOS-Chem) simulation for 2014, constrained by satellite-based estimates of PM2.5 to interpret globally dispersed PM2.5 mass and composition measurements from the ground-based surface particulate matter network (SPARTAN). Measured site mean PM2.5 composition varies substantially for secondary inorganic aerosols (2.4–19.7 μg/m3), mineral dust (1.9–14.7 μg/m3), residual/organic matter (2.1–40.2 μg/m3), and black carbon (1.0–7.3 μg/m3). Interpretation of these measurements with the GEOS-Chem model yields insight into sources affecting each site. Globally, combustion sectors such as residential energy use (7.9 μg/m3), industry (6.5 μg/m3), and power generation (5.6 μg/m3) are leading sources of outdoor global population-weighted PM2.5 concentrations. Global population-weighted organic mass is driven by the res...

Global-scale evidence for the refractory nature of riverine black carbon

Abstract: Wildfires and incomplete combustion of fossil fuel produce large amounts of black carbon. Black carbon production and transport are essential components of the carbon cycle. Constraining estimates of black carbon exported from land to ocean is critical, given ongoing changes in land use and climate, which affect fire occurrence and black carbon dynamics. Here, we present an inventory of the concentration and radiocarbon content (∆14C) of particulate black carbon for 18 rivers around the globe. We find that particulate black carbon accounts for about 15.8 ± 0.9% of river particulate organic carbon, and that fluxes of particulate black carbon co-vary with river-suspended sediment, indicating that particulate black carbon export is primarily controlled by erosion. River particulate black carbon is not exclusively from modern sources but is also aged in intermediate terrestrial carbon pools in several high-latitude rivers, with ages of up to 17,000 14C years. The flux-weighted 14C average age of particulate black carbon exported to oceans is 3,700 ± 400 14C years. We estimate that the annual global flux of particulate black carbon to the ocean is 0.017 to 0.037 Pg, accounting for 4 to 32% of the annually produced black carbon. When buried in marine sediments, particulate black carbon is sequestered to form a long-term sink for CO2.

Resolving the mechanisms of hygroscopic growth and cloud condensation nuclei activity for organic particulate matter

Abstract: Hygroscopic growth and cloud condensation nuclei activation are key processes for accurately modeling the climate impacts of organic particulate matter. Nevertheless, the microphysical mechanisms of these processes remain unresolved. Here we report complex thermodynamic behaviors, including humidity-dependent hygroscopicity, diameter-dependent cloud condensation nuclei activity, and liquid-liquid phase separation in the laboratory for biogenically derived secondary organic material representative of similar atmospheric organic particulate matter. These behaviors can be explained by the non-ideal mixing of water with hydrophobic and hydrophilic organic components. The non-ideality-driven liquid-liquid phase separation further enhances water uptake and induces lowered surface tension at high relative humidity, which result in a lower barrier to cloud condensation nuclei activation. By comparison, secondary organic material representing anthropogenic sources does not exhibit complex thermodynamic behavior. The combined results highlight the importance of detailed thermodynamic representations of the hygroscopicity and cloud condensation nuclei activity in models of the Earth's climate system.

Anthropogenic Emissions of Hydrogen Chloride and Fine Particulate Chloride in China.

Abstract: Particulate chloride (Cl–) can be transformed to nitryl chloride (ClNO2) via heterogeneous reaction with nitrogen pentoxide (N2O5) at night. Photolysis of ClNO2 and subsequent reactions of chlorine radical with other gases can significantly affect the atmospheric photochemistry. In China, the only available integrated anthropogenic chloride emission inventory was compiled in the 1990s with low spatial resolution, which hinders assessment of impact of ClNO2 on current air quality. In this study, we developed an up-to-date and high-resolution anthropogenic inventory of hydrogen chloride (HCl) and fine particulate Cl– emissions in China for 2014 with 0.1° × 0.1° resolution. Detailed local data and county-level activity data were collected and complied. The anthropogenic emissions of HCl and fine particulate Cl– in 2014 were estimated to be 458 and 486 Gg, respectively. Biomass burning was the largest contributor, accounting for 75% of fine particulate Cl– emission and 32% of HCl emission. Northeast China and...

Humic-Like Substances (HULIS) in Aerosols of Central Tibetan Plateau (Nam Co, 4730 m asl): Abundance, Light Absorption Properties, and Sources

Abstract: Humic-like substances (HULIS) are major components of light-absorbing brown carbon that play an important role in Earth’s radiative balance. However, their concentration, optical properties, and sources are least understood over Tibetan Plateau (TP). In this study, the analysis of total suspended particulate (TSP) samples from central of TP (i.e., Nam Co) reveal that atmospheric HULIS are more abundant in summer than that in winter without obvious diurnal variations. The light absorption ability of HULIS in winter is 2–3 times higher than that in summer. In winter, HULIS are mainly derived from biomass burning emissions in South Asia by long-range transport. In contrast, the oxidation of anthropogenic and biogenic precursors from northeast part of India and southeast of TP are major sources of HULIS in summer.

Influences of wind and precipitation on different-sized particulate matter concentrations (PM 2.5 , PM 10 , PM 2.5–10 )

Abstract: Though it is recognized that meteorology has a great impact on the diffusion, accumulation and transport of air pollutants, few studies have investigated the impacts on different-sized particulate matter concentrations. We conducted a systematic comparative analysis and used the framework of generalized additive models (GAMs) to explore the influences of critical meteorological parameters, wind and precipitation, on PM2.5, PM10 and PM2.5–10 concentrations in Wuhan during 2013–2016. Overall, results showed that the impacts of wind and precipitation on different-sized PM concentrations are significantly different. The fine PM concentrations decreased gradually with the increase of wind speed, while coarse PM concentrations would increase due to dust resuspension under strong wind. Wind direction exerts limited influence on coarse PM concentrations. Wind speed was linearly correlated with log-transformed PM2.5 concentrations, but nonlinearly correlated with log-transformed PM10 and PM2.5–10 concentrations. We also found the PM2.5 and PM2.5–10 concentrations decreased by nearly 60 and 15% when the wind speed was up to 6 m/s, respectively, indicating a stronger negative impact of wind-speed on fine PM than coarse PM. The scavenging efficiency of precipitation on PM2.5–10 was over twice as high as on PM2.5. Our findings may help to understand the impacts of meteorology on different PM concentrations as well as discriminate and forecast variation in particulate matter concentrations.

Fast particulate nitrate formation via N 2 O 5 uptake aloft in winter in Beijing

Abstract: . Particulate nitrate ( p NO 3 - ) is an important component of secondary aerosols in urban areas. Therefore, it is critical to explore its formation mechanism to assist with the planning of haze abatement strategies. Here we report vertical measurements of NOx and O3 by in situ instruments on a movable carriage on a tower during a winter heavy-haze episode (18 to 20 December 2016) in urban Beijing, China. Based on the box model simulation at different heights, we found that p NO 3 - formation via N2O5 heterogeneous uptake was negligible at ground level due to N2O5 concentrations of near zero controlled by high NO emissions and NO concentration. In contrast, the contribution from N2O5 uptake was large at high altitudes (e.g., > 150 m), which was supported by the lower total oxidant ( NO2 + O3 ) level at high altitudes than at ground level. Modeling results show the specific case that the nighttime integrated production of p NO 3 - for the high-altitude air mass above urban Beijing was estimated to be 50 µ g m −3 and enhanced the surface-layer p NO 3 - the next morning by 28 µ g m −3 through vertical mixing. Sensitivity tests suggested that the nocturnal NOx loss by NO3 – N2O5 chemistry was maximized once the N2O5 uptake coefficient was over 2 × 10 −3 on polluted days with Sa at 3000 µ m 2 cm −3 in wintertime. The case study provided a chance to highlight the fact that p NO 3 - formation via N2O5 heterogeneous hydrolysis may be an important source of particulate nitrate in the urban airshed during wintertime.

Effects of Wet Flue Gas Desulfurization and Wet Electrostatic Precipitators on Emission Characteristics of Particulate Matter and Its Ionic Compositions from Four 300 MW Level Ultralow Coal-Fired Power Plants

Abstract: To achieve ultralow-emission (ULE) standards, wet electrostatic precipitators (WESP) installed downstream from wet flue gas desulfurization (WFGD) have been widely used in Chinese coal-fired power ...

Contribution of Hydroxymethane Sulfonate to Ambient Particulate Matter: A Potential Explanation for High Particulate Sulfur During Severe Winter Haze in Beijing

Abstract: PM2.5 during severe winter haze in Beijing, China, has reached levels as high as 880 μg/m, with sulfur compounds contributing significantly to PM2.5 composition. This sulfur has been traditionally assumed to be sulfate, although atmospheric chemistry models are unable to account for such large sulfate enhancements under dim winter conditions. Using a 1-D model, we show that well-characterized but previously overlooked chemistry of aqueous-phase HCHO and S(IV) in cloud droplets to form a S(IV)-HCHO adduct, hydroxymethane sulfonate, may explain high particulate sulfur in wintertime Beijing. We also demonstrate in the laboratory that methods of ion chromatography typically used to measure ambient particulates easily misinterpret hydroxymethane sulfonate as sulfate. Our findings suggest that HCHO and not SO2 has been the limiting factor in many haze events in Beijing and that to reduce severe winter pollution in this region, policymakers may need to address HCHO sources such as transportation. Plain Language Summary Air pollution in Beijing is especially severe in winter, when concentrations of tiny particles in the air can reach concentrations over 20 times greater than the safe level recommended by theWorld Health Organization. In these severe pollution episodes, observations show that a large portion of the particles is made up of sulfur. Scientists have assumed that this sulfur is in the form of sulfate; however, computer simulations of air pollution chemistry have been unable to explain such high sulfate concentrations. We show with a simple computer simulation that a large portion of the sulfur in these haze episodes may, instead of sulfate, actually be a molecule called hydroxymethane sulfonate, which is formed by a chemical reaction in cloud droplets of dissolved formaldehyde with dissolved sulfur dioxide. We also show in laboratory experiments that the machines typically used for determining the chemical composition of particles easily misinterpret hydroxymethane sulfonate as sulfate. Importantly, the chemistry that produces hydroxymethane sulfonate is usually limited by formaldehyde, implying that reductions in sulfur dioxide would be ineffective at reducing severe haze. Instead, focusing future emissions reductions on formaldehyde emissions may be an effective way to curtail severe winter haze in the Beijing area.

Air Pollution, Noise, Blue Space, and Green Space and Premature Mortality in Barcelona: A Mega Cohort

Abstract: Introduction: Cities often experience high air pollution and noise levels and lack of natural outdoor environments, which may be detrimental to health. The aim of this study was to evaluate the effects of air pollution, noise, and blue and green space on premature all-cause mortality in Barcelona using a mega cohort approach. Methods: Both men and women of 18 years and above registered on 1 January 2010 by the Sistema d’Informacio pel Desenvolupament de la Investigacio en Atencio Primaria (SIDIAP) and living in the city of Barcelona were included in the cohort and followed up until 31 December 2014 or until death (n = 2,939,067 person years). The exposure assessment was conducted at the census tract level (n = 1061). We assigned exposure to long term ambient levels of nitrogen dioxides (NO2), nitrogen oxides (NOx), particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5), between 2.5 µm and 10 µm (PM2.5–10, i.e., coarse particulate matter), less than 10 µm (PM10) and PM2.5 light absorption (hereafter referred to as PM2.5 absorbance) based on land use regressions models. Normalized Difference Vegetation Index (NDVI) was assigned based on remote sensing data, percentage green space and blue space were calculated based on land use maps and modelled road traffic noise was available through the strategic noise map for Barcelona. Results: In this large prospective study (n = 792,649) in an urban area, we found a decreased risk of all-cause mortality with an increase in green space measured as NDVI (hazard ratio (HR) = 0.92, 95% CI 0.89–0.97 per 0.1) and increased risks of mortality with an increase in exposure to blue space (HR = 1.04, 95% CI 1.01–1.06 per 1%), NO2 (HR = 1.01, 95% CI 1.00–1.02 per 5 ug/m3) but no risk with noise (HR = 1.00, 95% CI 0.98–1.02 per 5 dB(A)). The increased risks appeared to be more pronounced in the more deprived areas. Results for NDVI, and to a lesser extent NO2, remained most consistent after mutual adjustment for other exposures. The NDVI estimate was a little attenuated when NO2 was included in the model. The study had some limitations including e.g., the assessment of air pollution, noise, green space and socioeconomic status (SES) on census tract level rather than individual level and residual confounding. Conclusion: This large study provides new insights on the relationship between green and blue space, noise and air pollution and premature all-cause mortality.

Causes and consequences of decreasing atmospheric organic aerosol in the United States

Abstract: Exposure to atmospheric particulate matter (PM) exacerbates respiratory and cardiovascular conditions and is a leading source of premature mortality globally. Organic aerosol contributes a significant fraction of PM in the United States. Here, using surface observations between 1990 and 2012, we show that organic carbon has declined dramatically across the entire United States by 25–50%; accounting for more than 30% of the US-wide decline in PM. The decline is in contrast with the increasing organic aerosol due to wildfires and no clear trend in biogenic emissions. By developing a carbonaceous emissions database for the United States, we show that at least two-thirds of the decline in organic aerosol can be explained by changes in anthropogenic emissions, primarily from vehicle emissions and residential fuel burning. We estimate that the decrease in anthropogenic organic aerosol is responsible for averting 180,000 (117,000–389,000) premature deaths between 1990 and 2012. The unexpected decrease in organic aerosol, likely a consequence of the implementation of Clean Air Act Amendments, results in 84,000 (30,000–164,000) more lives saved than anticipated by the EPA between 2000 and 2010.