Mass Concentrations Of PM2 Research Articles

Determination of atmospheric aerosol components in an urban area to evaluate the air quality and identify the sources of contamination.

The need to generate objective evidence and reliable information for decision makers to improve environmental policies for a better air quality, led us to evaluate the atmospheric aerosol components in the urban area of Carabayllo, by monitoring PM2.5 and PM10 to determine mass concentration and analyzing PM10 using k 0-INAA and ICP-MS for metals quantification, ion chromatography for anions and the NIOSH method to determine organic and elemental carbon. The results obtained from mass concentration of PM2.5 and PM10 exceeded the permissible breathing annual average of WHO guidelines of 15µgm-3 and 45µgm-3, respectively, which evidence an unhealthy air quality. Likewise, using the model Positive Matrix Factorization five sources of pollutants were defined: metallurgical industry, sea salt, industrial activity, dust and non-exhaust emissions and vehicle emissions.

Measurement report: Chemical components and 13C and 15N isotope ratios of fine aerosols over Tianjin, North China: year-round observations

Abstract. To better understand the origins and seasonality of atmospheric aerosols in North China, we collected fine aerosols (PM2.5) at an urban site (Nankai District, ND) and a suburban site (Haihe Education Park, HEP) in Tianjin from July 2018 to July 2019. The PM2.5 was studied for carbonaceous, nitrogenous and ionic components and stable carbon and nitrogen isotope ratios of total carbon (δ13CTC) and nitrogen (δ15NTN). On average, the mass concentrations of PM2.5, organic carbon (OC), elemental carbon (EC) and water-soluble OC (WSOC) were higher in winter than in summer at both ND and HEP. SO42-, NO3- and NH4+ were the dominant ions, and their sum accounted for 89 % of the total ionic mass at ND and 87 % at HEP. NO3- and NH4+ peaked in winter and were at their minimum in summer, whereas SO42- was higher in summer than in all the other seasons at HEP and was comparable among the seasons, although it peaked in winter at ND. δ13CTC and δ15NTN were −26.5 ‰ to −21.9 ‰ and +1.01 ‰ to +22.8 ‰ at ND and −25.5 ‰ to −22.8 ‰ and +4.91 ‰ to +18.6 ‰ at HEP. Based on seasonal variations in the measured parameters, we found that coal and biomass combustion emissions are the dominant sources of PM2.5 in autumn and winter, while terrestrial and/or marine biological emissions are important in spring and summer in the Tianjin region, North China. In addition, our results implied that the secondary formation pathways of secondary organic aerosols in autumn/winter were different from those in spring/summer; i.e., they might be driven by NO3 radicals in the former period.

Size-Resolved Field Performance of Low-Cost Sensors for Particulate Matter Air Pollution.

Particulate matter (PM) air pollution is a major health hazard. The health effects of PM are closely linked to particle size, which governs its deposition in (and penetration through) the respiratory tract. In recent years, low-cost sensors that report particle concentrations for multiple-sized fractions (PM1.0, PM2.5, PM10) have proliferated in everyday use and scientific research. However, knowledge of how well these sensors perform across the full range of reported particle size fractions is limited. Unfortunately, erroneous particle size data can lead to spurious conclusions about exposure, misguided interventions, and ineffectual policy decisions. We assessed the linearity, bias, and precision of three low-cost sensor models, as a function of PM size fraction, in an urban setting. Contrary to manufacturers' claims, sensors are only accurate for the smallest size fraction (PM1). The PM1.0-2.5 and PM2.5-10 size fractions had large bias, noise, and uncertainty. These results demonstrate that low-cost aerosol sensors (1) cannot discriminate particle size accurately and (2) only report linear and precise measures of aerosol concentration in the accumulation mode size range (i.e., between 0.1 and 1 μm). We recommend that crowdsourced air quality monitoring networks stop reporting coarse (PM2.5-10) mode and PM10 mass concentrations from these sensors.

Analysis of PM2.5 Characteristics in Yancheng from 2017 to 2021 Based on Kolmogorov–Zurbenko Filter and PSCF Model

Based on the hourly monitoring data including meteorological elements and PM2.5 mass concentration in Yancheng from 2017 to 2021, PM2.5 mass concentration variations, influencing factors and source apportionment were studied by the Kolmogorov–Zurbenko filter and Potential Source Contribution Function Analysis (PSCF) method. The results showed that the mass concentration of PM2.5 in Yancheng showed a decreasing trend from 2017 to 2021, with a decline rate of about 33.8% (2017, 44.79 ± 31.22 μg/m3; 2021, 29.66 ± 21.69 μg/m3); the visibility increased by 18.4% (2017, 11.69 ± 6.46 km; 2021,13.8 ± 6.24 km), which is mainly related to emission reduction measures in China. The mass concentration of PM2.5 has significant seasonal variation characteristics, with the highest in winter, reaching 60.61 μg/m3, and the lowest in summer, only 23.11 μg/m3. The diurnal variation of PM2.5 showed a unimodal distribution, and concentration difference is obvious under the influence of land–sea breeze (36.60 μg/m3, easterly wind; 43.57 μg/m3, westerly wind). Meteorological factors have an important impact on the mass concentration of PM2.5, which fluctuates with seasons. It is calculated to have a good fitting relationship between the visibility and PM2.5 concentration, and the correlation decreases with the increase in humidity (−0.71 ~ −0.41). The relatively clean atmosphere under high humidity conditions is also prone to the obstruction to vision. The corresponding PM2.5 concentration varies significantly under different wind directions and wind speeds in Yancheng, and high values mainly come from the northwest–southeast–southwest direction. The potential source regions in autumn are mainly distributed in southwestern Jiangsu and northwestern Zhejiang; the potential source regions in winter are mainly located in southwestern Jiangsu, southern Anhui and northern Jiangxi.

Impacts of a Prescribed Fire on Air Quality in Central New Mexico

A short-duration but high-impact air quality event occurred on 28 November 2018 along the Rio Grande Valley of New Mexico. This fire occurred outside the typical wildfire season, and greatly impacted the air quality in Socorro, NM, and the surroundings. Measurements were taken during the event using an aerosol light scattering technique (integrating nephelometer) and a particulate mass concentration monitor (DustTrak PM optical monitor). The instruments sampled the ambient air during the event on the campus of the New Mexico Institute of Mining and Technology in Socorro, New Mexico. The peak values on a 5-min basis of light scattering and the PM mass concentration reached 470 Mm−1 and 270 µg/m3, respectively. We examined the meteorological context of the event using local meteorological data and back trajectories using the NOAA HYSPLIT model to determine atmospheric transport and possible sources. Several fires, both prescribed and wildfires, occurred in the region including a prescribed burn at Bosque del Apache National Wildlife Refuge (17 km south-southeast of the receptor site). The data suggest that the prescribed burn at Bosque del Apache was the dominant contributor due to transport evidence and the event’s narrow spatiotemporal extent. The increasing importance of restoring ecosystem function using prescribed fire in wildland fire management will likely lead to more frequent air quality impacts and sets up policy tradeoffs that require a balance between these public goals. This study examines the evidence of the effects of a prescribed fire in a protected wildland area impacting the air quality in a nearby populated area.

The pattern and mechanism of an unhealthy air pollution event in Lanzhou, China

To study the patterns and mechanisms of unhealthy air pollution events in Lanzhou, China, meteorological factors, synoptic conditions and regional transportation circumstances were analysed. The results showed that the average daily mass concentrations of PM10 and PM2.5 were 3646.0 μg/m3 and 668.0 μg/m3, respectively; the average value of PM2.5/PM10 was less than 30%, indicating that this event was caused by PM10. WPSCF and WCWT analyses showed that the contribution sources of PM2.5 and PM10 were diverse. A large-scale high-pressure ridge lasted for a long period and was prone to long-term calm winds that reduced the transportation, dilution and diffusion of pollutants. The formation of this unhealthy air pollution event was closely related to the large-scale high-pressure ridge and the trough-shaped topography of the valley.

Air Pollution and Birth Outcomes: Health Impact and Economic Value Assessment in Spain.

Air pollution is considered an ongoing major public health and environmental issue around the globe, affecting the most vulnerable, such as pregnant women and fetuses. The aim of this study is to estimate the health impact and economic value on birth outcomes, such as low birthweight (LBW), preterm birth (PTB), small for gestational age (SGA), attributable to a reduction of PM10 levels in Spain. Reduction based on four scenarios was implemented: fulfillment of WHO guidelines and EU limits, and an attributable reduction of 15% and 50% in annual PM10 levels. Retrospective study on 288,229 live-born singleton children born between 2009-2010, using data from Spain Birth Registry Statistics database, as well as mean PM10 mass concentrations. Our finding showed that a decrease in annual exposure to PM10 appears to be associated with a decrease in the annual cases of LBW, SGA and PTB, as well as a reduction in hospital cost attributed to been born with LBW. Improving pregnancy outcomes by reducing the number of LBW up to 5% per year, will result in an estimate associated monetary saving of 50,000 to 7,000,000 euros annually. This study agrees with previous literature and highlights the need to implement, and ensure compliance with, stricter policies that regulate the maximum exposure to outdoor PM permitted in Spain, contributing to decreased environmental health risk, especially negative birth outcomes.

Impact of aging on the sources, volatility, and viscosity of organic aerosols in Chinese outflows

Abstract. To investigate the impact of aging on the sources, volatility, and viscosity of organic aerosol (OA) in Chinese outflows, a high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) coupled with a thermodenuder (TD) was deployed in the spring of 2018 in Dongying, which is a regional receptor site of metropolitan emissions in the North China Plain (NCP). The average mass concentration of PM1 is 31.5±22.7 µg m−3, which is mainly composed of nitrate (33 %) and OA (25 %). The source apportionment results show that the OA is mainly contributed by oxygenated OA (OOA) from secondary sources, including background-OOA (33 %) representing a background concentration of OA (2.6 µg m−3) in the NCP area, and transported-OOA (33 %) oxidized from urban emissions. The other two factors include aged hydrocarbon-liked OA (aged-HOA, 28 %) from transported vehicle emissions and biomass burning OA (BBOA, 5 %) from local open burning. The volatility of total OA (average C*=3.2×10-4 µg m−3) in this study is generally lower than that reported in previous field studies, which is mainly due to the high OA oxidation level resulting from aging processes during transport. The volatilities of OA factors follow the order of background-OOA (average C*=2.7×10-5 µg m−3) < transported-OOA (3.7×10-4µgm-3)< aged-HOA (8.1×10-4µgm-3)< BBOA (0.012 µg m−3). Extremely low volatilities in ambient air indicate that oligomers may exist in aged plumes. The viscosity estimation suggests that the majority of ambient OA in this study behaves as semisolid (60 %), liquifies at higher relative humidity (RH) (21 %), and solidifies (19 %) during noon when the RH is low and the oxidation level is high. Finally, the estimated mixing time of molecules in 200 nm OA varies dramatically from minutes at night to years in the afternoon, emphasizing the need to consider its dynamic kinetic limits when modeling OA. In general, the overall results of this study improve our understanding of the impact of aging on OA volatility and viscosity.

First insight into seasonal variability of urban air quality of northern Pakistan: An emerging issue associated with health risks in Karakoram-Hindukush-Himalaya region

There is a dire need of air quality monitoring in the high-mountain areas of Karakoram-Hindu Kush-Himalaya (HKH) region, particularly related to the recent activities undergoing the China-Pakistan Economic Corridor (CPEC). This study presents the first baseline monitoring and evaluation findings from Gilgit city, Gilgit-Baltistan. Hourly data collection for air quality parameters (PM2.5, NO, NO2, SO2, O3 and CO) were measured using air-pointer (recordum, Austria) from 1 Jan 2018 to 31 Mar 2018 (winter) and 1 Jun 2018 to 31 Aug 2018 (summer). Our findings depict PM2.5 health limits were crossed in the winter season, while NO, NO2 and SO2 remained below their health limits. O3 and CO showed a rising trend in summer months, crossing the 8-h health limits during the season. Seasonal correlation in meteorology found an inverse relationship between most parameters and temperatures; reverse was true for O3 and CO. In parallel, thermal optical carbon analysis filter-based sampling characterized air quality into mass concentrations of PM2.5, organic carbon (OC), elemental carbon (EC) and various heavy metals. Filter-based PM2.5 correlated well with analyzer-based PM2.5 for all months that were studied, except February and March 2018. PM2.5, OC and EC were higher in summer as compared to winter, whereas higher heavy metal contributions were measured predominantly during summer. Health impacts were found to be above health limits for Ni in children only. Furthermore, principal component analysis-multiple linear regression (PCA-MLR) technique was applied to determine source apportionment, confirming the role of biomass burning in winters, and vehicular emissions in summers, highlighting the need for flexible monitoring of technologies/approaches, and communications among the various public, private agencies, and all relevant stakeholders.

Emission Characteristics of Fine Particles in Relation to Precursor Gases in Agricultural Emission Sources: A Case Study of Dairy Barns

Recently, precursor gases such as ammonia have sparked a growing interest in the secondary formation of particulate matter (PM). Most studies focus on urban areas and scientific data. Studies on precursor gases and PM emitted from agricultural sources are insufficient; thus, this paper presents a field monitoring study conducted from agricultural sources. To estimate the effect of precursor gases for PM2.5 from naturally ventilated dairy barns, correlation analyses were conducted using real-time monitoring data on the mass concentrations of PM2.5, NH3, SO2, NO2, and H2S and meteorological data. In addition to mass concentration, the emission and loading rates were used to closely analyze pollution status. The mass concentrations of PM2.5 and gaseous compounds did not correlate well, whereas the mass emission rates for PM2.5 and gaseous compounds (SO2, NH3, and NO2) correlated well because the unit of the emission rate reflected the ventilation factor. The correlation coefficients between PM2.5 and precursor gas emission rates ranged from 0.72 to 0.89 (R), with the SO2 emission rate exhibiting the highest correlation coefficient (R = 0.89). This correlation implies that SO2 from dairy farms is a dominant species among the gaseous precursors influencing the secondary formation of PM2.5; alternatively, SO2 and PM2.5 are produced from the same sources. The ambient PM2.5 loading rate and barn PM2.5 emission rate—estimated by multivariate linear regression using the gaseous independent variables NH3, SO2, and NO2—revealed high-correlation coefficients (0.60 and 0.92, respectively) with the measured data. At present, most studies investigating the precursor gases of PM in agricultural fields have focused on NH3; however, this study suggests that SO2 is a key factor in PM2.5 pollution. To elucidate the secondary formation of PM from precursor gases in agricultural sources, particulate ammonium, sulfate, nitrate, and chloride, which were not measured in this study, as well as oxidants and intermediates, should be considered in future research.

Civil air quality monitoring as an alternative and supplement to the National Air Quality Monitoring Network

The European initiatives for citizens? inclusion in the air quality monitoring process have impacted the participants? knowledge, and attitudes towards air pollution and have led to a higher sense of community toward activities and measures against air pollution. In the Republic of Serbia, an experiment with self-made sensor kits "Klimerko - Air to the Citizens" started in 2018. In this paper, we have presented the level of agreement of the PM readings from selected Klimerko devices to the PM readings of the reference equivalent PM monitors from the National Air Quality Monitoring Network in the cities of Bor and Belgrade. The Klimerko devices that we tested showed excellent stability and reliability during the comparison period. The conclusion of our investigation is that the properly calibrated Klimerko devices could be applied for indicative measurements of PM mass concentrations in the ambient air.

Characteristics of air quality changes in Quanzhou during the COVID-19 epidemic

On January 8, 2020, there was an outbreak of coronavirus disease 19 (COVID-2019), and on January 24, 2020, Fujian Province issued the "Fujian Provincial Emergency Plan for Public Health Emergencies", which restricted crowd gathering activities such as markets, greatly reducing transportation and industry. The difference between air quality before and after the epidemic was studied, and the results show that the mass concentrations of SO2, NO2, CO, PM10, and PM2.5 in Quanzhou City in February 2020 all decreased in January, with decline rates of 5.8–8.8%, 34.7–46.7%, 14.9–25.1%, 9.4–15.9%, and 5.4– 14.3%; O3 did not show the same change pattern. NO2, CO, O3, PM10, and PM2.5 decreased compared with the same period in 2018 and 2019, of which SO2 and NO2 declined the most, and CO and O3 declined the least. The spatial distribution map of air quality in Quanzhou City in the first half of 2020 was obtained by the Arcgis anti-distance weighting method, and the results showed that the Qingyuanshan area had the best air quality in Quanzhou and was the least affected by the epidemic; the air quality in Tushan Street and Jintoupu changed the most, showing the most obvious impact of the epidemic. The changes in air quality in Quanzhou during the epidemic period show that traffic and industrial pollution sources were more likely to be affected by the epidemic, and the sources of domestic pollution were relatively stable.

Spatiotemporal, Morphological and Source Analysis of Ultrafine Particulates (PM1) over Bengaluru, Karnataka, India

Measurement and analysis of Particulate Matter of aerodynamic diameter less than 1µm (PM1) has been carried out using indigenously built air sampler at the following locations of Bengaluru city: Basavanagudi (BAS), Domlur (DOM), Hosur road (HOS) and DC Halli (DCH). The PM1mass concentrations were observed to vary from 20.16 µg/m3 to 68.64 µg/m3 during the study period. The highest mass concentration of 68.64 µg/m3 was observed for the location BAS and the lowest mass concentration of 20.16 µg/m3 was observed for the location DOM. The average mass concentration of PM1 around Bengaluru for winter, summer, monsoon & post monsoon season is observed to be 47.60 µg/m3, 40.24 µg/m3, 30.85 µg/m3 and 38.76 µg/m3 respectively. Some of the collected samples showed the presence of microorganism such as bacillus. Elemental composition analysis showed the presence of non-metals Carbon, Oxygen, Nitrogen, Sulphur and traces of metals such as Sodium, Aluminium, Calcium and Potassium.

PM10 Element Distribution and Environmental-Sanitary Risk Analysis in Two Italian Industrial Cities

In this work, an evaluation of the air of two Italian industrial cities, Turin and Biella, has been performed to identify the main sources affecting its quality and to evaluate its evolution along 15 years. These two cities are placed at the border of the Po valley, one of the most polluted areas of Europe, and the automotive and textile industries have been their main economic sectors. The elemental analysis of the PM10 collected there in 2007 has been performed by ICP-MS and ICP-AES. The results identify the urban activities and the soil/road dust resuspension as the main sources of metals. Biella was overall less polluted in PM10 than Turin, probably because of its smaller size, its smaller traffic volume, and the lower number of industries. However, the limit value imposed by the European legislation for daily average PM10 mass concentration (50 μg m−3) was frequently exceeded in the collected samples: 22% and 50%, respectively for Biella and Turin. The concentration of specific toxic metals regulated by Italian legislation was never higher than the limit value for Cd (4 ng m−3) and Pb (0.5 μg m−3), whereas it was exceeded for Ni (20 ng m−3) in 22% of the samples from Turin and only in the 5% of those from Biella. In the same way, the risk analysis, performed using the target hazard quotient (THQ), calculated for children and adult populations, did not reveal warning values. Only for Cd in children were concerning values found (median THQ = 4.9). Element concentrations showed a seasonal trend, with higher values in November and December due to a combination of stable atmospheric conditions and strengthening of anthropic sources (e.g., combustion for heat generation). Finally, data concerning the amount of Cd, Ni, and Pb in the atmosphere provided by the regional agency for environmental protection (ARPA Piedmont) have been used to follow the evolution of these elements from 2007 to 2021 in the two cities. The data reveal a significant reduction of the concentrations of all considered metals in all the sites (higher than 50%), however maintaining the seasonal variability observed in PM10 samples of 2007, with higher concentrations during the cold months and lower concentrations during the summer.

Source apportionment of PM2.5 using PMF combined online bulk and single-particle measurements: Contribution of fireworks and biomass burning

Fireworks (FW) could significantly worsen air quality in short term during celebrations. Due to similar tracers with biomass burning (BB), the fast and precise qualification of FW and BB is still challenging. In this study, online bulk and single-particle measurements were combined to investigate the contributions of FW and BB to the overall mass concentrations of PM2.5 and specific chemical species by positive matrix factorization (PMF) during the Chinese New Year in Hong Kong in February 2013. With combined information, fresh/aged FW (abundant 140K2NO3+ and 213K3SO4+ formed from 113K2Cl+ discharged by fresh FW) can be extracted from the fresh/aged BB sources, in addition to the Second Aerosol, Vehicles + Road Dust, and Sea Salt factors. The contributions of FW and BB were investigated during three high particle matter episodes influenced by the pollution transported from the Pearl River Delta region. The fresh BB/FW contributed 39.2% and 19.6% to PM2.5 during the Lunar Chinese New Year case. However, the contributions of aged FW/BB enhanced in the last two episodes due to the aging process, evidenced by high contributions from secondary aerosols. Generally, the fresh BB/FW showed more significant contributions to nitrate (35.1% and 15.0%, respectively) compared with sulfate (25.1% and 5.9%, respectively) and OC (14.8% and 11.1%, respectively) on average. In comparison, the aged FW contributed more to sulfate (13.4%). Overall, combining online bulk and single-particle measurement data can combine both instruments’ advantages and provide a new perspective for applying source apportionment of aerosols using PMF.

Variations in black carbon and particulate matters (PM1, PM2.5 and PM10) during firecrackers bursting episodes and biomass burning: A case study during the Diwali festival


 
 
 
 Introduction: The Black Carbon (BC) and Particulate Matters (PMs) was measured in the Diwali festival during 3-7 November, 2021. Diwali is being one of the main festivals of India accompanied by lighting and firecrackers bursting.
 Materials and methods: BC concentration was measured by aerosol black carbon low-cost sensor/detector and PM1, PM2.5 and PM10 mass concentration as well as number concentration was measured using Grimm Aerosol Spectrometer at Agra, India.
 Results: Average mass of PM1 (<1 μm), PM2.5 ( <2.5 μm) and PM10 ( <10 μm) were 218.32±56.82 μg/m3, 261.56±74.38 μg/m3 and 380.40±67.78 μg/ m3 respectively in Diwali day (2021). The observed concentration of PM was much higher than National Ambient Air Quality Standards (NAAQS) and World Health Organization (WHO) standard limits. Diurnal peaks for all the pollutants (PM1, PM2.5 and PM10) were perceived in the evening time which was due to festival celebration events. Particle Size number Distribution (PSND) showed one major peak in the particle <1 μm size range. BC mass concentration was found to be 16.28±5.62 μg/m3 in Diwali days. BC/PMs ratio decreases as the PM size increases due to the heavy load of PM2.5.
 Conclusion: BC and PM concentration was significantly amplified on Diwali due to firecrackers bursting and candles and biomass burning which was responsible for the poor air quality. Particle Mass Size Distribution (PSMD) showed multiple peaks while PSND showed one major peak in fine mode. Higher PM1/PM2.5 indicated the abundance of fine particles as compared to coarse. BC concentration was increased by 20 % on Diwali day due to firecracker bursting, other burning materials and more vehicles movement.
 
 
 

Chemical Compositions, Sources, and Intra‐Regional Transportation of Submicron Particles Between North China Plain and Twain‐Hu Basin of Central China in Winter

AbstractRegional submicron particles (PM1) compositions, sources, and interaction are still not clear as the desynchrony in observation. This study focused on PM1 at five sites synchronously in North China Plain and Central China during January 2018. The average PM1 mass concentrations decreased from north to south, with higher values in Luohe (125 ± 59.4 μg m−3), followed by borderline cities (54.1–93.3 μg m−3) and a south site of Wuhan (63.6 ± 21.5 μg m−3). Organic matter (41.8%–51.0%) and secondary inorganic aerosols (SIAs; 28.2%–33.2%) occupied the high fractions for all the five sites. Coal combustion and industrial processes mainly raised the differences in PM1 chemical compositions between regions. The changes of NO3−/SO42− between sites were different as a function of relatively humidity and temperature, reflecting the differences of secondary formation mechanism. For a short intraregional transport case from south to north, PM1 increased from 102 to 185 μg m−3 as the accumulation and aerosol‐planet boundary layer interaction under a stable meteorological condition. For a long‐range transport case from north to south with a high wind speed (5.5 m s−1) and boundary layer height (529 m), PM1 decreased by only 0.9 μg m−3 (−1.3%) as the enhanced formation of SIA by 12.6% under increased relative humidity (by 7.2%) and enhanced industrial emission (by 19.1%) at the south site. The results provide a useful data set for modeling PM1 chemical compositions and their impacts and are helpful for regional‐joint control of atmospheric particles and precursor gases.

Improved indoor air quality during desert dust storms: The impact of the MEDEA exposure-reduction strategies

Desert dust storms (DDS) are natural events that impact not only populations close to the emission sources but also populations many kilometers away. Countries located across the main dust sources, including countries in the Eastern Mediterranean, are highly affected by DDS. In addition, climate change is expanding arid areas exacerbating DDS events. Currently, there are no intervention measures with proven, quantified exposure reduction to desert dust particles. As part of the wider “MEDEA” project, co-funded by LIFE 2016 Programme, we examined the effectiveness of an indoor exposure-reduction intervention (i.e., decrease home ventilation during DDS events and continuous use of air purifier during DDS and non-DDS days) across homes and/or classrooms of schoolchildren with asthma and adults with atrial fibrillation in Cyprus and Crete-Greece. Participants were randomized to a control or intervention groups, including an indoor intervention group with exposure reduction measures and the use of air purifiers. Particle sampling, PM10 and PM2.5, was conducted in participants' homes and/or classrooms, between 2019 and 2022, during DDS-free weeks and during DDS days for as long as the event lasted. In indoor and outdoor PM10 and PM2.5 samples, mass and content in main and trace elements was determined. Indoor PM2.5 and PM10 mass concentrations, adjusting for premise type and dust conditions, were significantly lower in the indoor intervention group compared to the control group (PM2.5-intervention/PM2.5-control = 0.57, 95% CI: 0.47, 0.70; PM10-intervention/PM10-control = 0.59, 95% CI: 0.49, 0.71). In addition, the PM2.5 and PM10 particles of outdoor origin were significantly lower in the intervention vs. the control group (PM2.5 infiltration intervention-to-control ratio: 0.49, 95% CI: 0.42, 0.58; PM10 infiltration intervention-to-control ratio: 0.68, 95% CI: 0.52, 0.89). Our findings suggest that the use of air purifiers alongside decreased ventilation measures is an effective protective measure that reduces significantly indoor exposure to particles during DDS and non-DDS in high-risk population groups.

Staggered-peak production is a mixed blessing in the control of particulate matter pollution.

Staggered-peak production (SP)-a measure to halt industrial production in the heating season-has been implemented in North China Plain to alleviate air pollution. We compared the variations of PM1 composition in Beijing during the SP period in the 2016 heating season (SPhs) with those in the normal production (NP) periods during the 2015 heating season (NPhs) and 2016 non-heating season (NPnhs) to investigate the effectiveness of SP. The PM1 mass concentration decreased from 70.0 ± 54.4 μg m-3 in NPhs to 53.0 ± 56.4 μg m-3 in SPhs, with prominent reductions in primary emissions. However, the fraction of nitrate during SPhs (20.2%) was roughly twice that during NPhs (12.7%) despite a large decrease of NOx, suggesting an efficient transformation of NOx to nitrate during the SP period. This is consistent with the increase of oxygenated organic aerosol (OOA), which almost doubled from NPhs (22.5%) to SPhs (43.0%) in the total organic aerosol (OA) fraction, highlighting efficient secondary formation during SP. The PM1 loading was similar between SPhs (53.0 ± 56.4 μg m-3) and NPnhs (50.7 ± 49.4 μg m-3), indicating a smaller difference in PM pollution between heating and non-heating seasons after the implementation of the SP measure. In addition, a machine learning technique was used to decouple the impact of meteorology on air pollutants. The deweathered results were comparable with the observed results, indicating that meteorological conditions did not have a large impact on the comparison results. Our study indicates that the SP policy is effective in reducing primary emissions but promotes the formation of secondary species.

The Effect of Students, Computers, and Air Purifiers on Classroom Air Quality

Indoor air pollutant sources are crucial in assessing IAQ, especially when outdoor air pollutant concentrations are low. In the present study, PM mass concentrations in a range of five sizes; CO, CO2, O3, NO, NO2, and TVOC concentrations; along with temperature and relative humidity were monitored in three indoor locations of a university. The monitoring took place in a building dedicated to teaching undergraduates. The first two locations, a professor’s office and a computer centre (laboratory), were not refurbished. The classroom under study is refurbished and now is airtight, as are all of the classrooms in this building. Air purifiers were installed in all of the classrooms to prevent the transmission of infectious pollutants. In all monitored locations, people were the main indoor source of PM, CO2, and TVOC. The operation of twelve computers in the small laboratory did not contribute to the air pollution, at least for the examined pollutants. The air purifier decreased the PM concentrations, but not the gaseous air pollutants.