Reduction In PM2 Research Articles

Rigorous Regional Air Quality Standards for Substantial Health Benefits

AbstractFollowing a series of actions in China, the annual mean fine particle (PM2.5) concentrations have considerably reduced since 2013. However, in some cities, the PM2.5 concentrations exceed the national ambient air quality standard of 35 μg/m3. Herein, we evaluated the historical trends of PM2.5 from 2014 to 2022 in mainland China and found continuously declining trends. However, the annual decline rates decreased despite increasing investments on pollution control, showing considerably diminishing marginal effects of these investments. Accumulative reduction in PM2.5 concentrations is linearly dependent on the log‐transformed accumulative investment in air pollution control. The standard of 35 μg/m3 can be achieved by 2035 if the current efforts continue at the same pace. However, the standard of 35 μg/m3 can weaken the momentum of future actions in cities where the standard has already been implemented. We proposed and tested two tiers with four or six levels of specific regional standards based on the regression model predictions from the historical data and demonstrated that more rigorous standards for regions where the current standard is already attained could provide more momentum for strengthening abatement efforts. The results show that both tiers are feasible if the level of abatement endeavor is maintained even with marginal effects. We also demonstrate that additional 135,000 or 384,000 deaths can be avoided by applying the regional standards. Health benefits are monetized and compared with the control costs, suggesting that compared to Tier‐2, Tier‐1 is more cost‐effective and balanced across the mainland China.

Emission reduction and cost-benefit analysis of the use of ammonia and green hydrogen as fuel for marine applications

Increasingly stringent emission standards have led shippers and port operators to consider alternative energy sources which can reduce emissions while minimizing capital investment. It is essential to understand whether there is a certain economic investment gap for alternative energy. The present work mainly focuses on the simulation study of ships using ammonia and hydrogen fuels arriving at Guangzhou Port to investigate the emission advantages and cost-benefit analysis of ammonia and hydrogen as alternative fuels. By collecting actual data and fuel consumption emissions of ships arriving at Guangzhou Port, the present study calculated the pollutant emissions and cost of ammonia and hydrogen fuels substitution. As expected, it is shown that with the increase of NH3 in fuel, mixed fuels will effectively reduce CO and CO2 emissions. Compared to conventional fuel, the injection of NH3 increases the NOx emission. However, the cost savings of ammonia fuel for CO2, SOx and PM10 reduction are higher than that for NOx. In terms of pollutants, ammonia is less expensive than conventional fuels when applied to the Guangzhou Port. However, the cost of fuel supply is still higher than conventional energy as ammonia has not yet formed a complete fuel supply and storage system for ships. On the other hand, hydrogen is quite expensive to store and transport, resulting in higher overall costs than ammonia and conventional fuels, even if no pollutants are produced. At present, conventional fuels still have advantage in terms of cost. With the promotion of ammonia fuel technology and application, the cost of supply will be reduced. It is predicted that by 2035 ammonia will not only have emission reduction benefits, but also will have a lower overall economic cost than conventional fuels. Hydrogen energy will need longer development and technological breakthroughs due to the limitation of storage conditions.

Investigation of computer numerical control wood milling parameters for occupationally safer by the minimization of produced wood dust

ABSTRACT Computer numerical control (CNC) wood machining produces wood dust, harming the operator's health. In this research, the effective parameters of the amount of produced wood dust (PM) in CNC milling are investigated. The design of the experiment was done based on the response surface method (RSM) and subsequently, 27 experimental tests were performed. The results of the analysis of variance show that the parameters of the depth of cut (ap ), step over (ae ), feed rate (vw ) and cutting speed (vc ) have a great impact on PM, respectively. Changing these machining parameters leads to severe changes in the PM (0.043–11.200 mg/m3). Also in 78% of experimental tests, the amount of PM is higher than the National Institute for Occupational Safety and Health (NIOSH) standard value (1 mg/m3). In the next step, for the reduction and minimization of PM, a quadratic regression equation was derived. After model validation, the model was minimized by the distance-based optimality method at Minitab software. Optimization result shows that by choosing the optimum parameters ap = 3 mm, vw = 50 mm/s, vc = 15,393 rpm and ae = 6.270 mm, PM is reduced to 0.011 mg/m3, which is much lower (about 89%) than the NIOSH standard value. This prediction was tested and validated by the experimental test.

Is air pollution joint prevention and control effective in China-evidence from "Air Pollution Prevention and Control Action Plan".

This paper examined the effect of air pollution joint prevention and control on pollution emissions in China. Specifically, based on the panel data of 290 cities from 2007 to 2021, taking the implementation of the "Air Pollution Prevention and Control Action Plan" as a natural experiment, the difference-in-difference-in-difference (DDD) model was used to explore the effect of air pollution joint prevention and control on haze pollution. Results show that air pollution joint prevention has a significant impact on pollutant emissions either as a whole or as a single pollutant. In terms of individual urban agglomeration, whether the Yangtze River Delta or the Pearl River Delta urban agglomerations, the air pollution joint prevention and control policy has a significant impact not only on the overall reduction of pollutant emissions but also on the reduction of single PM2.5 or industrial sulfur dioxide emissions alone. Environmental regulations have also achieved the effect of haze control in general and have a significant impact on the reduction of PM2.5 or industrial sulfur dioxide emissions. Environmental regulations also significantly reduced PM2.5 emissions in these three urban agglomerations. These findings provide a scientific basis and essential reference for understanding the implementation effect of regional joint prevention and control policies comprehensively and objectively.

Quantifying the impact of lockdown measures on air pollution levels: A comparative study of Bhopal and Adelaide

This research study presents an in-depth comparison of air quality in Bhopal, India, and Adelaide, Australia, focusing on the impact of COVID-19 restrictions. Utilizing air quality data from 2019 to 2022, the research analyzed the concentrations of pollutants like PM2.5, PM10, NO2, and O3, during pre-lockdown, lockdown, and post-lockdown periods. The findings demonstrate a significant reduction in PM2.5and PM10 levels during lockdown in cities such as Delhi and Haryana in India, and various Chinese cities, while also highlighting complex sources of air pollution like bushfires in regions like Sydney, Australia. In contrast, the study revealed nuanced trends in Bhopal and Adelaide, influenced by local geographical, climatic, and anthropogenic factors. Bhopal exhibited a notable decrease in PM10 and PM2.5levels, but inconsistent patterns in NO2 and CO, while Adelaide experienced marginal changes. The study emphasizes the temporary effectiveness of lockdowns and underscores the need for region-specific, sustainable air quality management strategies. Future implications include considerations for regional specificities, broader atmospheric chemistry, and international collaboration. The research provides valuable insights for urban air quality policy formulation, stressing a data-driven, long-term approach.

Analysis of Spatio-temporal Characteristics of Air Quality, Meteorological Impact, and Emission Reduction Effect During the Winter Olympics in Beijing-Tianjin-Hebei and Its Surrounding Areas

From January 31st to February 20th, 2015 to 2022, the spatio-temporal characteristics of the PM2.5 pollution evolution of 44 cities in the Beijing-Tianjin-Hebei Region and its surrounding areas were analyzed. The contribution of simultaneous meteorology, coordinated emission reduction, and cross-regional transmission to PM2.5 concentration and chemical component changes were quantified, respectively, with the aim to provide scientific reference for regional air quality joint prevention and control under adverse meteorological conditions. The results showed that the mean value of PM2.5 concentration of 44 cities in 2022 was the lowest(46 μg·m-3) without heavy pollution in the same period of the lunar calendar since 2015, whereas the proportion of days with good air quality was the highest(83.3%). PM2.5 pollution was more serious in the southern region than that in the northern region, and the high values were mainly concentrated along the Taihang Mountains and Yanshan transmission channel cities. In 2016, under the unregulated emission of fireworks in the Spring Festival, the proportion of unpolluted days was 93.5%, which means that the strong atmospheric diffusion ability was crucial to improve air quality. In 2022, the static weather index(SWI) increased by 2.1 compared with that in 2021, indicating unfavorable atmospheric diffusion capacity. The average and peak values of PM2.5 decreased by 14 μg·m-3 and 76 μg·m-3, respectively. The reduction in PM2.5 concentration in Beijing owing to emission reduction measures increased by 96% compared with that before one month. Under the adverse atmospheric background in the Shanxi-Shandong-Henan Region, which contributed to the increase in PM2.5 concentration, the peak value of PM2.5 concentration decreased by 87 μg·m-3, indicating that the peak clipping effect of regional collaborative pollution emission reduction was significant. From 2019 to 2022, the concentration of PM2.5 chemical components decreased yearly with narrowed spatial differences, and the high value was concentrated in the central and southern regions. The descending order of PM2.5 secondary component concentration decrease was as follows:organic matter(21.9%)>sulfate(20%)>ammonium salt(16.7%)>nitrate(9.7%). The proportion of nitrate in PM2.5 increased yearly to 30.1%, indicating that the contribution of traffic pollution was relatively prominent. In 2022, the SNA concentration in the Shanxi-Shandong-Henan Region increased. Pollution from external sources accounted for the main contribution in the Beijing-Tianjin-Hebei Region(>50%). Liaoning Province contributed significantly to the PM2.5 concentration in cities along the Bohai(>10%), and nitrate and sulfate were easy to transport over long distances. It is necessary to strengthen the coordinated control of precursors of secondary chemical components SO2, NOx, and NH3.

Elucidating the Impacts of Meteorology and Emission Changes on Concentrations of Major Air Pollutants in Major Cities in the Yangtze River Delta Region Using a Machine Learning De-weather Method

This study applied a de-weather method based on a machine learning technique to quantify the contribution of meteorology and emission changes to air quality from 2015 to 2021 in four cities in the Yangtze River Delta Region. The results showed that the significant reductions in PM2.5, NO2, and SO2 emissions(57.2%-68.2%, 80.7%-94.6%, and 81.6%-96.1%, respectively) offset the adverse effects of meteorological conditions, resulting in lower pollutant concentrations. The meteorological contribution of maximum daily 8-h average O3(MDA8_O3) showed a stronger effect than that of others(23.5%-42.1%), and meteorological factors promoted the increase in MDA8_O3 concentrations(4.7%); however, emission changes overall resulted in a decrease in MDA8_O3 concentrations(-3.2%). NO2 and MDA8_O3 decreased more rapidly from 2019 to 2021, mainly because the emissions played a stronger role in reducing pollutant concentrations than from 2015 to 2018. However, emissions changes had weaker reduction effects on PM2.5 and SO2 from 2019 to 2021 than from 2015 to 2018. De-weather methods could effectively seperate the effects of meteorology and emission changes on pollutant trends, which helps to evaluate the real effects of emission control policies on pollutant concentrations.

Fine Particulate Matter Reduction through Crop Surface Adsorption in an Agricultural Field Using the Coefficient Derived from Wind Tunnel Experiments

Fine dust can have serious effects on human health and crop growth. Fodder crops can reduce airborne dust by coagulating soil particles and reducing wind speed on the surface and have the effect of reducing fine dust by adsorbing it on the crop surface. In this study, the dust reduction coefficient of crops was derived through a self-manufactured wind tunnel experiment to quantitatively assess the dust reduction effect of crops by type and planting density. Additionally, a dust reduction formula considering crop growth and weather conditions during the cultivation period was derived. The dust reduction coefficient was measured by the gravimetric method and the real-time size distribution of dust concentration before and after the crop. The PM reduction coefficient showed triticale at PM-2.5 82.2 mg/m3, PM-10 120 mg/m3, and barley at PM-2.5 14.5 mg/m3, PM-10 26.9 mg/m3 under moderate planting density. During the general planting density cultivation period of triticale and barley, PM-10 was reduced by 37.8 kg/ha and 8.5 kg/ha, respectively, and PM-2.5 was reduced by 25.9 kg/ha and 4.6 kg/ha. The dust reduction effect during the cultivation period was up to 126.1 kg/ha in terms of PM-10 when triticale was cultivated with densely sowing planting density.

Simulating impacts on UK air quality from net-zero forest planting scenarios

Abstract. The UK proposes additional bioenergy plantations and afforestation as part of measures to meet net-zero greenhouse gas emissions, but species and locations are not yet decided. Different tree species emit varying amounts of isoprene and monoterpene volatile organic compounds that are precursors to ozone and secondary organic aerosol (SOA) formation, the latter of which is a component of PM2.5. The forest canopy also acts as a depositional sink for air pollutants. All these processes are meteorologically influenced. We present here a first step in coupling information on tree species planting suitability and other planting constraints with data on UK-specific BVOC emission rates and tree canopy data to simulate, via the WRF-EMEP4UK high spatial-resolution atmospheric chemistry transport model, the impact on UK air quality of four potential scenarios. Our “maximum planting” scenarios are based on planting areas where yields are predicted to be ≥ 50 % of the maximum from the Ecological Site Classification decision support system (ESC DSS) for Eucalyptus gunnii, hybrid aspen (Populus tremula), Italian alder (Alnus cordata) and Sitka spruce (Picea sitchensis). The additional areas of forest in our scenarios are 2.0 to 2.7 times the current suggestions for new bioenergy and afforestation land cover in the UK. Our planting scenarios increase UK annual mean surface ozone concentrations by 1.0 ppb or 3 % relative to the baseline land cover for the highest BVOC-emitting species (e.g. E. gunnii). Increases in ozone reach 2 ppb in summer when BVOC emissions are greatest. In contrast, all the additional planting scenarios lead to reductions in UK annual mean PM2.5 – ranging from −0.2 µg m−3 (−3 %) for Sitka spruce to −0.5 µg m−3 (−7 %) for aspen – revealing that PM2.5 deposition to the additional forest canopy area more than offsets additional SOA formation. Relative decreases in annual mean PM2.5 are greater than the relative increases in annual mean ozone. Reductions in PM2.5 are least in summer, coinciding with the period of maximum monoterpene emissions. Although only a first step in evaluating the impact of increased forest plantation on UK air quality, our study demonstrates the need for locally relevant data on land cover suitability, emissions and meteorology in model simulations.

Does PM2.5 accelerate the firm evolution? Evidence from 800-mm isoline in China

Accurately recognizing the impact and mechanism of PM2.5 on firms is essential for China to achieve both the reduction of PM2.5 and economic growth. Based on the differing levels of PM2.5 concentration between both sides of the 800 mm isoline, we construct a quasi-natural experiment to investigate the impact of PM2.5 on firm evolution and regional economic efficiency. We further evaluate the role of government governance in achieving both PM2.5 reduction and regional economic efficiency improvements simultaneously. Results indicate that M2.5 disturb the process of firm evolution and influences regional economic efficiency through different effects. More importantly, the results show that in regions with strong governance, reducing PM2.5 could improve macroeconomic efficiency without hampering economic growth. In contrast, regions with weak governance tend to experience an increase in PM2.5 severity as economic growth advances. The evidence presented in this paper on the relationship between PM2.5 and economic development provides a new perspective to formulate policies for policymakers.

Field based performance evaluation of optimized improved biomass mud cookstoves in rural India

The present work assesses the real-world performance of novel improved mud-based cookstoves (MBC) - Pavak 1 (P1) and Pavak 2 (P2) in a remote community in Khandwa, Madhya Pradesh, India. These MBC's were designed using multi-parameter optimization based on extensive laboratory testing. These MBCs are affordable and durable, and can be locally manufactured without compromising cooking quality, taste, or convenience while still meeting the Indian cookstove performance standards (BIS IS 13152 (Part 1): 2013) for emissions and efficiency. MBC's performance was compared to traditional stoves (TS) in accordance with the ISO 19869:2019 cookstove field testing protocol. 45 cooking sessions were captured (22 P1; 13 P2; 10 TS). Fuel-based emission factors (EF) for PM2.5 and CO were estimated using the carbon balance method. Results indicate reductions in PM2.5 (56% for P1 and 46% for P2) and CO emissions (15% for P1 and 0.85% for P2) compared to TS. Analysis of real-time modified combustion efficiencies showed that MBCs exhibited prolonged periods in pure flaming conditions compared to TS. A user perception survey was conducted in the intervention households to understand community acceptability. Our results demonstrate the potential for increased adoption rates, emphasizing the importance of information, education, and communication (IEC) programs to maximize health and climate benefits.

The sensitivity of health impact assessments of PM2.5 from South African coal-fired power stations

Unabated emissions of precursor gases from coal-fired power stations in South Africa greatly contribute to ambient PM2.5 concentration in the region, but estimates of the number of associated premature mortalities vary vastly. The application of the exposure-response function is one of the reasons for the differences in estimates of premature mortalities; since the relationship between mortality and PM2.5 exposure flattens out at higher PM2.5 concentrations, a smaller number of premature mortalities is calculated if a reduction in PM2.5 concentration occurs at the actual ambient concentration (“avoidable deaths”), while a greater number of mortalities is calculated if other sources are not considered (at low ambient concentrations) (“single-source deaths”). It is more appropriate to attribute deaths to a source in proportion to the contribution made by the source to ambient PM2.5 levels (“attributable deaths”). Total ambient PM2.5 concentrations are extrapolated from 38 ambient monitoring stations in the north-eastern region of South Africa using a regression model based on household socio-economic factors, and PM2.5 concentrations derived from power station emissions are estimated using a reduced-form intake fraction model. It is estimated that there are around 800 attributable premature mortalities per year due to PM2.5 from coal-fired power station emissions in South Africa. The number of premature mortalities is 44% higher when calculating single-source deaths and 53% lower when calculating avoidable deaths. Using the attributable death approach is particularly important in highly polluted areas such as low-income residential areas where households use solid and liquid fuels.

Towards Cleaner Cities: An Analysis of the Impact of Bus Fleet Decomposition on PM and NOX Emissions Reduction in Sustainable Public Transport

The problem of poor air quality in urban areas has a negative impact on the health of residents. This is especially important during periods of smog. In Poland, as in other countries, the problem of poor air quality, especially during the winter season, is associated with a high concentration of particulate pollutants in ambient air (PM10, PM2.5). Sources of particulate emissions, in addition to solid-fuel boilers, include means of transportation, especially those equipped with diesel engines. In turn, during periods of strong sunshine (spring and summer), the problem of photochemical smog, whose precursors are nitrogen oxides NOX, arises in urban areas. Their main sources of emissions are internal combustion engines. Therefore, to improve air quality in urban areas, changes are being made in the transport sector, among which is upgrading the fleet of urban transport vehicles to low- or zero-emission vehicles, which are more environmentally friendly. In addition, measures that reduce the harmfulness of the transportation sector to air quality include the introduction of clean transportation zones, as well as park-and-ride (P&R) systems. The purpose of this article is to present the results in terms of PM10, PM2.5, and NOx emission reductions, implemented over a period of two years (2021–2022) in the area of the Rzeszow agglomeration, related to the modernization of the suburban bus fleet and the implementation of a P&R system for passenger cars. The results of the study were compared with the value of estimated emissions from coal-fired boilers used for residential heating and hot water, which also contribute to smog. Thanks to the implementation of the project, i.e., the replacement of 52 old buses with new buses of the Euro VI emission class and the construction of new P&R spaces, the total average annual reduction in emissions amounted to approximately 703.6 kg of PM10, approximately 692.7 kg of PM2.5, and a reduction of approximately 10.4 tons of NOX.

Effects of preheating temperature, O2 distribution concentration and combustion temperature on the formation of PM during preheating-low NO combustion

Clarifying the mechanism of multi-mode PM formation during pulverized coal preheating-combustion is expected to facilitate the synergistic control of NO and PM, and a significant low carbon way to achieve clean combustion. In this study, combustion experiments under different preheating-combustion conditions were conducted in a preheating-combustion furnace. Based on this, a system coupling design was explored by combining preheating-combustion with air staging. The results demonstrated a significant simultaneous reduction in both PM and NO during preheating-combustion, achieving a synergistic control of PM and NO emissions. With an increase in preheating temperature(Tp), the NO formation decreased, while the PM10 formation increased. Increasing the excess air coefficient(αp) reduced the PM10 formation, while the NO exhibited a trend of initially decreasing and then increasing. The impact of the combustion temperature(Tc) on NO and PM was more pronounced, especially with a significant increase of 80.59% in the PM0.3 (from 1300 K to 1700 K). Furthermore, the effect of the interaction of the three factors on NO: αp and Tc > αp and Tp > Tp and Tc. After coupling preheating-combustion with air staging, the formation of NO and PM0.3 decreased by 33.27% and 17.43%, respectively, compared to the preheating-combustion baseline.

Jasmonic Acid Effect on Cucumis sativus L. Growth Is Related to Inhibition of Plasma Membrane Proton Pump and the Uptake and Assimilation of Nitrates.

When plants are exposed to environmental stress, their growth is inhibited. Under such conditions, controlled inhibition of growth is beneficial for plant survival. Jasmonic acid (JA) is a well-known phytohormone that limits plant growth, which has been confirmed in several species. However, its role in cucumber seedlings has not yet been comprehensively investigated. For this reason, we aimed to determine the involvement of JA in the regulation of proteins crucial for growth including plasma membrane proton pump (PM H+-ATPase), PM nitrate transporters, and nitrate reductase (NR). Treatment of cucumber seedlings with JA not only limited their growth but also increased the H2O2 content in their roots. The main sources of ROS generated for signalling purposes are PM NADPH oxidase (RBOH) and superoxide dismutase (SOD). Exposure of seedlings to JA induced the expression of some CsRBOH and SOD encoding genes, suggesting that ROS signalling can be activated by JA. As a consequence of JA exposure, the activity of all analysed proteins was inhibited and the expression of their genes was modified. The results indicate that reduction of PM H+-ATPase activity and the related decrease in nitrate uptake and assimilation are responsible for the root growth retardation of JA-treated plants.

Utilizing Low-Cost Sensors to Monitor Indoor Air Quality in Mongolian Gers.

Air quality has important climate and health effects. There is a need, therefore, to monitor air quality both indoors and outdoors. Methods of measuring air quality should be cost-effective if they are to be used widely, and one such method is low-cost sensors (LCS). This study reports on the use of LCSs in Ulaanbataar, Mongolia to measure PM2.5 concentrations inside yurts or "gers". Some of these gers were part of a non-government agency (NGO) initiative to improve insulating properties of these housing structures. The goal of the NGO was to decrease particulate emissions inside the gers; a secondary result was to lower the use of coal and other biomass material. LCSs were installed in gers heated primarily by coal, and interior air quality was measured. Gers that were modified by increasing their insulating capacities showed a 17.5% reduction in PM2.5 concentrations, but this is still higher than recommended by health organizations. Gers that were insulated and used a combination of both coal and electricity showed a 19.1% reduction in PM2.5 concentrations. Insulated gers that used electricity for both heating and cooking showed a 48% reduction in PM2.5 but still had higher concentrations of PM2.5 that were 6.4 times higher than recommended by the World Health Organization (WHO). Nighttime and daytime trends followed similar patterns and trends in PM2.5 concentrations with slight variations. It was found that at nighttime the outside PM2.5 concentrations were generally higher than the inside concentrations of the gers in this study, meaning that PM2.5 would flow into the ger whenever the doors were opened, causing spikes in PM2.5 concentrations.

Residential green and blue spaces with nonalcoholic fatty liver disease incidence: Mediating effect of air pollutants

BackgroundThis study aimed to investigate the relationship of residential green and blue spaces with incident nonalcoholic fatty liver disease (NAFLD), and explore the potential mediation effects of air pollutants and modification effect of genetic susceptibility. Methods411,200 UK Biobank participants without prior liver diseases were included. Land use data were used to estimate residential green and blue spaces (land coverage percentage) at 300 m and 1000 m buffer. The study outcome was incident NAFLD, ascertained through linkage to hospital admissions and death registry records. Results5198 NAFLD cases were documented after a median follow-up of 12.5 years. Green and blue spaces were inversely associated with the hazard of NAFLD: per standard deviation (SD) increment of green space coverage at 300 m (SD: 14.5 %; HR, 0.88, 95 %CI, 0.86–0.91) and 1000 m (SD: 14.1 %; HR, 0.88, 95 %CI, 0.86–0.91) buffer, and blue space coverage at 300 m (SD: 1.0 %; HR,0.95, 95 %CI, 0.93–0.98) and 1000 m (SD: 1.2 %; HR,0.96, 95 %CI, 0.93–0.99) buffer were related with a 4–12 % reduction of NAFLD incidence. The beneficial effects of approximately 25–52 % of green space exposure and about 5–35 % of blue space exposure on NAFLD incidence were mediated by the reduction of PM2.5, NO2 and NOx (All Pindirect effect <0.05). Moreover, genetic susceptibility of NAFLD did not modify the relationship of green and blue spaces with NAFLD incidence. ConclusionResidential green and blue spaces were inversely related to NAFLD incidence. These results suggest that green and blue spaces are modifiable factors that may help prevent NAFLD, and therefore, can be considered as a novel environmental strategy to promote liver health at the community level, rather than only at the individual level.

The air pollution tradeoff in India: saving more lives versus reducing the inequality of exposure

Chronic exposure to ambient fine particulate matter (PM2.5) represents one of the largest global public health risks, leading to millions of premature deaths annually. For a country facing high and spatially variable exposures, prioritizing where to reduce PM2.5 concentrations leads to an inherent tradeoff between saving the most lives and reducing inequality of exposure. This tradeoff results from the shape of the concentration–response (C-R) function between exposure to PM2.5 and mortality, which indicates that the additional lives saved per unit reduction in PM2.5 declines as concentrations increase, suggesting that more lives can be saved by reducing exposures in clean locations than in dirty locations. We estimated this C-R function for urban areas of India, finding that a 10 µgm−3 reduction in PM2.5 in already-clean locations will reduce the mortality rate substantially (4.2% for a reduction from 30 to 20 µgm−3), while a 10 µgm−3 reduction in the dirtiest locations will reduce mortality only modestly (1.2% for a reduction from 90 to 80 µgm−3). Policymakers face a troubling tradeoff between maximizing lives saved and reducing the inequality of exposure. Many air pollution policies impose an upper limit on exposure, thereby cleaning the dirtiest locations and reducing exposure inequality. We explore the implications of this PM2.5/mortality relationship by considering a thought experiment. If India had a fixed amount of resources to devote to PM2.5 concentration reductions across urban areas, what is the lives saved/inequality of exposure tradeoff from three different methods of deploying those resources? Across our three scenarios: (1) which reduces exposures for the dirtiest districts, (2) which reduces exposures everywhere equally, and (3) which reduces exposures to save the most lives—scenario 1 saves 18 000 lives per year while reducing the inequality of exposure by 65%, while scenario 3 saves 126 000 lives per year, but increases inequality by 19%.

Engine preheating under real-world subfreezing conditions provides less than expected benefits to vehicle fuel economy and emission reduction for light-duty vehicles

Six light-duty vehicles, both gasoline- and diesel-fueled, were driven a prescribed 13.8 km route in a real-world low-traffic environment under Finnish subfreezing winter conditions (−28 ... −10 °C). Cold starts, hot starts, and starts with different preheating strategies were used. Fuel consumption and emissions of particles and nitrogen oxides (NOx) were examined by a chasing method with a mobile laboratory. Both electric preheaters (0.3–1.2 kW) and fuel-operated auxiliary heaters (5 kW) were used in the experiments where a cold engine was preheated before starting. While most vehicles showed potential for reducing fuel consumption and emissions of particles (PM), black carbon (BC), and NOx during hot starts compared to subfreezing-cold starts, the benefits of preheating were relatively small and limited to only a few vehicles. The fuel consumption for the 13.8 km drive decreased less than 4% with one gasoline vehicle and one diesel vehicle by preheating. These two vehicles are both equipped with a fuel-operated auxiliary heater, and taking the fuel consumption of the heater during preheating into account leads to about 30% higher total fuel consumption, canceling the preheating benefit out. These two vehicles also showed the largest reductions in PM, BC, and NOx emissions achieved with preheating, e.g., the PM emission reductions being 72% (the gasoline vehicle) and 24% (the diesel vehicle). Whereas the NOx emission reduction for this gasoline vehicle was 41% when considering only the drive, it decreases to 15% when the NOx emissions from the auxiliary heater during preheating are also taken into account. High particle number (PN) emissions from all vehicles and NOx emissions from the diesel vehicles were detected. The PN emissions of particles larger than 23 nm were up to 2 orders of magnitude higher and the NOx emissions up to a factor of 21 higher than the corresponding limits in the European regulations for type-approval of new vehicles. The PN emissions did not depend on the start types; thus, no benefits to reduce them with preheating were detected. The limit-exceeding PN emissions are partially explained with the used measurement method for PN taking both nonvolatile and semivolatile particles into account, whereas the regulations take only the nonvolatile particles into account. The PM emissions were also observed to consist mostly of semivolatile material in most of the cases, organics being the main component of the semivolatile material.

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.