Lower Concentrations Of PM2 Research Articles

Particle-ozone complex pollution under diverse synoptic weather patterns in the Yangtze River Delta region: Synergistic relationships and the effects of meteorology and chemical compositions

There is considerable academic interest in the particle-ozone synergistic relationship (PO) between fine particulate matter (PM2.5) and ozone (O3). Using various synoptic weather patterns (SWPs), we quantitatively assessed the variations in the PO, which is relevant to formulating policies aimed at controlling complex pollution in the air. First, based on one-year sampling data from March 2018 to February 2019, the SWPs classification of the Yangtze River Delta (YRD) was conducted using the sum-of-squares technique (SS). Five dominant SWPs can be found in the YRD region, including the Aleutian low under SWP1 (occurring 45 % of the year), a tropical cyclone under SWP2 (21 %), the tropical cyclone and western Pacific Subtropical High (WPSH) under SWP3 (15.4 %), the WPSH under SWP4 (6.9 %), and a continental high pressure under SWP5 (3.1 %). The phenomenon of a “seesaw” between PM2.5 and O3 concentrations exhibited significant spatial heterogeneity, which was influenced by meteorological mechanisms. Second, the multi-linear regression (MLR) model and the partial correlation (PCOR) analysis were employed to quantify the effects of dominant components and meteorological factors on the PO. Meteorological variables could collectively explain only 33.0 % of the PM2.5 variations, but 58.0 % for O3. O3 promoted each other with low concentrations of PM2.5 but was inhibited by high concentrations of PM2.5. High relative humidity (RH) was conducive to the generation of PM2.5 secondary components and enhanced the radiative effects of aerosols and the negative correlation of PO. In addition, attention should be paid to assessing the combined effects of precursor levels, weather, and chemical reactions on the particle-ozone complex pollution. The control of O3 pollutants should be intensified in summer, while the focus should be on reducing PM2.5 pollutants in winter. Prevention and control measures need to reflect the differences in weather conditions and pollution characteristics, with a focus on RH and secondary components of PM2.5.

Spatiotemporal characterization of PM2.5, O3, and trace gases associated with East Asian continental outflows via drone sounding

East Asian continental outflows with PM2.5, O3, and other species may determine the baseline conditions and affect the air quality in downwind areas via long-range transport (LRT). To gain insight into the impact and spatiotemporal characteristics of airborne pollutants in East Asian continental outflows, a versatile multicopter drone sounding platform was used to simultaneously observe PM2.5, O3, CO2, and meteorological variables (temperature, specific humidity, pressure, and wind vector) above the northern tip of Taiwan, Cape Fuiguei, which often encounters continental outflows during winter monsoon periods. By coordinating hourly high-spatial-resolution profiles provided by drone soundings, WRF/CMAQ model air quality predictions, HYSPLIT-simulated backward trajectories, and MERRA-2 reanalysis data, we analyzed two prominent phenomena of airborne pollutants in continental outflows to better understand their physical/chemical characteristics. First, we found that pollutants were well mixed within a sounding height of 500 m when continental outflows passed through and completely enveloped Cape Fuiguei. Eddies induced by significant fluctuations in wind speeds coupled with minimal temperature inversion and LRT facilitated vertical mixing, possibly resulting in high homogeneity of pollutants within the outflow layer. Second, the drone soundings indicated exceptionally high O3 concentrations (70–100 ppbv) but relatively low concentrations of PM2.5 (10–20 μg/m3), CO2 (420–425 ppmv), and VOCs in some air masses. The low levels of PM2.5, CO2, and VOCs ruled out photochemistry as the cause of the formation of high-level O3. Further coordination of spatiotemporal data with air mass trajectories and O3 cross sections provided by MERRA-2 suggested that the high O3 concentrations could be attributed to stratospheric intrusion and advection via continental outflows. High-level O3 concentrations persisted in the lower troposphere, even reaching the surface, suggesting that stratospheric intrusion O3 may be involved in the rising trend in O3 concentrations in parts of East Asia in recent years in addition to surface photochemical factors.

Variability of Air Pollutants in the Indoor Air of a General Store

This research investigates different facets of indoor air quality and the corresponding health symptoms within a retail environment. Formaldehyde, classified as a Group B carcinogenic substance, was found within safe limits indoors, primarily originating from surface coatings, flooring products, textiles, and furniture. Monoterpenes, lactic acid, and particulate matter levels were also assessed, with varying indoor–outdoor ratios. Notably, we identified a relatively low concentration of PM2.5, possibly influenced by enhanced cleaning practices during the COVID-19 pandemic. Symptom assessment revealed that many young workers experienced work-related symptoms, notably fatigue, nose-, throat-, and skin-related issues, aligning with previous findings. Although we could not conclusively link these symptoms to sick building syndrome (SBS) or formaldehyde exposure, it underscores the importance of further investigation. Notably, we observed no gender-based differences in symptom prevalence, but this study’s limited size requires caution in generalization. This study contributes to understanding indoor air quality and associated symptoms in an economically significant sector, emphasizing the need for continued research, especially considering the potential impact on workforce health in the broader context.

Impacts of PM2.5 before and after COVID-19 outbreak on emergency mental disorders: A population-based quasi-experimental and case-crossover study

The ongoing COVID-19 pandemic is a great challenge to mental health, but fine particulate matter (PM2.5), an increasingly reported risk factor for mental disorders, has been greatly alleviated during the pandemic in many countries. It remains unknown whether COVID-19 outbreak can affect the association between PM2.5 exposure and the risk of mental disorders. This study aimed to investigate the associations of total and cause-specific mental disorders with PM2.5 exposure before and after the COVID-19 outbreak in China. Data on daily emergency department visits (EDVs) and hospitalizations of mental disorders from 2016 to 2021 were obtained from Anhui Mental Health Center for Hefei city. An interrupted time series analysis was used to quantify the impact of COVID-19 outbreak on EDVs and hospitalizations of mental disorders. A time-stratified case-crossover analysis was employed to evaluate the association of mental disorders with PM2.5 exposure before and after the COVID-19 outbreak, especially in the three months following the COVID-19 outbreak. After COVID-19 outbreak, there was an immediate and significant decrease in total mental disorders, including a reduction of 15% (95% CI: 3%–26%) in EDVs and 44% (95% CI: 36%–51%) in hospitalizations. PM2.5 exposure was associated with increased risk of EDVs and hospitalizations for total and cause-specific mental disorders (schizophrenia, schizotypal and delusional disorders; neurotic, stress-related, and somatoform disorders) before COVID-19 outbreak, but this PM2.5-related risk elevation significantly decreased after COVID-19 outbreak, with greater risk reduction at the first month after the outbreak. However, young people (0–45 years) were still vulnerable to PM2.5 exposure after the COVID-19 outbreak. This study first reveals that the risk of PM2.5-related emergency mental disorders decreased after the COVID-19 outbreak in China. The low concentration of PM2.5 might benefit mental health and greater efforts are required to mitigate air pollution in the post-COVID-19 era.

Mild exposure to fine particulate matter promotes angiogenesis in non-small cell lung carcinoma

Fine particulate matter (PM2.5) is associated with public health problems worldwide. Especially, PM2.5 induces epigenetic and microenvironmental changes in lung cancer. Angiogenesis is important for the development and growth of cancer and is mediated by angiogenic factors, including vascular endothelial growth factor. However, the effects of mild PM2.5 exposure on angiogenesis in lung cancer remain unclear. In this study, we examined angiogenic effects using relatively lower concentrations of PM2.5 than in other studies and found that PM2.5 increased angiogenic activities in both endothelial cells and non-small cell lung carcinoma cells. PM2.5 also promoted the growth and angiogenesis of lung cancer via the induction of hypoxia-inducible factor-1α (HIF-1α) in a xenograft mouse tumor model. Angiogenic factors, including vascular endothelial growth factor (VEGF), were highly expressed in lung cancer patients in countries with high PM2.5 levels in the atmosphere, and high expression of VEGF in lung cancer patients lowered the survival rate. Collectively, these results provide new insight into the mechanisms by which mild exposure to PM2.5 is involved in HIF-1α-mediated angiogenesis in lung cancer patients.

Time-lagged relationships between a decade of air pollution exposure and first hospitalization with Alzheimer's disease and related dementias

Alzheimer's disease and related dementias (ADRD) poses substantial health challenges among an aging population. One of the primary challenges in studying ADRD is that biological processes underlying these ailments begin decades prior to diagnosis. Previous studies indicate a relationship between ADRD and air pollution exposure to both fine particulate matter (PM2.5) and nitrogen dioxide (NO2) but are limited in their interpretation because they consider exposure measurements at a single time point. Our retrospective cohort study considered 27 + million Medicare enrollees in the United States followed up to 17 years and matched with highly accurate annual air pollution exposure measurements for PM2.5, NO2, and summer ozone. We applied distributed lag models and estimated the lagged associations between air pollution and odds of first hospitalization with ADRD. We found significantly increased odds due to overall PM2.5 and NO2 exposure and time-lagged exposure 10 and 8 years prior to admission, respectively. Furthermore, we found the connection between air pollution exposure and increased odds of first hospitalization with ADRD exists at air pollution levels below current National Ambient Air Quality Standards set by the US Environmental Protection Agency, with the steepest increase in odds occurring at low concentrations of PM2.5. Our findings are the first to show that air pollution exposures from as many as 10 years prior to the admission are related to increased odds of hospitalizations with ADRD. As there are no clear treatments available for ADRD, identifying modifiable risk factors such as air pollution exposure may make significant contributions towards prevention or delayed disease progression.

Tanshinone IIA-regulation of IL-6 antagonizes PM2 .5 -induced proliferation of human bronchial epithelial cells via a STAT3/miR-21 reciprocal loop.

Particulate matter 2.5 (PM2.5 ), a component of atmospheric particulate matter, leads to changes in gene expression and cellular functions. Epidemiological evidence confirms that PM2.5 has a positive correlation with lung injury. However, the molecular mechanisms involved remain poorly understood, and preventive methods are needed. In the present study, with human bronchial epithelial (HBE) cells in culture, we showed that low concentrations of PM2.5 resulted in acceleration of the G1/S transition and cell proliferation. Consistent with these effects, expression of the pro-inflammatory factor interleukin-6 (IL-6) was elevated in HBE cells exposed to PM2.5 . Accordingly, signal transducer and activator of transcription 3 (STAT3) was activated, which down-regulated expression of cyclin D1. In addition, PM2.5 exposure led to higher levels of miR-21, and there was a reciprocal loop between miR-21 and STAT3. For HBE cells, tanshinone IIA (Tan IIA) reversed the PM2.5 -induced cell cycle alteration and cell proliferation, and reduced the expression of cytokines (IL-6, STAT3, and miR-21). These results show that, for HBE cells, Tan IIA attenuates the PM2.5 -induced G1/S alteration and cell proliferation, and indicate that it has potential clinical application for PM2.5 -induced respiratory injuries.

Particulate matter 2.5 induced hyperpigmentation in reconstructed human epidermis model (MelaKutis®).

Particulate matter 2.5 induced hyperpigmentation in reconstructed human epidermis model (MelaKutis®).

Application of GIS in modelling real time population exposure to PM2.5

Air pollution has caused many deaths globally across all age groups with most of the deaths attributed to PM2.5 which is an extremely small sized particulate matter that can travels deep in to the lungs, hit the blood stream and affect the respiratory track. This study has estimated Southampton spatiotemporal population exposure to air pollution using the Surface builder (SB) 24/7 model and a modelled air pollution data from DEFRA with a specific focus on the variation in the level of exposure to PM 2.5 by different population age groups, using GIS. After modeling the population exposure the resulted map was resampled to 200m by 200m to match the spatial resolution of the output population distribution model. The result shows that only few areas around the southern parts of the study areas (mostly residential areas with low commercial activities) have low concentration of PM2.5 pollutant. The results further identified a significant variation in the level of exposure by different population age groups with the population age group between the age of 18 to 64 (non-students) having the highest level of exposure at both 2am (55% of the exposed population) and 2pm (52%). On the other hand, the age group with the lowest level of exposure (2%), at both times of the day, is 16 to 17 years of age. 18 to 64 years old students in higher education (HE) and people of over 65 years of age are second subgroups highly exposed while the remaining age groups (0 to 4, 5 to 9, 10 to 15) show almost similar exposure (5 to 6%) in both times of the day. Overall, there is an incredible difference in exposure to PM2.5 by different age groups which reflects the level of spatial interaction by each age group.

Abstract P067: Left Ventricular Hypertrophy And Inflammation Modify The Harmful Effects Of Fine Particulate Matter On Sudden Death

Sudden death accounts for approximately 10% of deaths among working age adults and is associated with poor air quality. We hypothesize that clinical risk factors for sudden death would modify the relationship of fine particulate matter (PM 2.5 ) to sudden death. Sudden death victims in Wake County, NC from 3/1/2013 - 2/28/2015 were identified by screening Emergency Medical Services (EMS) reports and adjudicated based on EMS, medical, and death records (n=399). Daily PM 2.5 concentrations for Wake County from the Air Quality Data Mart were linked to event and control periods for each individual. Using a case-crossover design, conditional logistic regression estimated OR (95%CI) for sudden death for a 5μg/m 3 increase in PM 2.5 with a 1-day lag, adjusted for temperature and humidity, across risk factor strata. Sensitivity analysis assessed consistency of main effects. Left ventricular hypertrophy (LVH) and neutrophil to lymphocyte ratio (NLR) were included as estimates of arrhythmic potential and inflammation, respectively. Low concentrations of PM 2.5 are potential risk factors for sudden death (Table 1). However, no clinical risk factors for sudden death modify that association. LVH and NLR, in contrast to clinical risk factors, are associated PM 2.5 and sudden death. Sensitivity analysis had no effect on the direction and minimal effect on the magnitude of the associations. Left ventricular hypertrophy and inflammation may be the final step in the mechanism whereby poor air quality and clinical risk factors trigger arrhythmia or myocardial ischemia and sudden death. This abstract does not necessarily reflect EPA policy.

The Synergistic Effect of PM2.5 and CO2 Concentrations on Occupant Satisfaction and Work Productivity in a Meeting Room.

High indoor air quality is crucial for the health of human beings. The purpose of this work is to analyze the synergistic effect of particulate matter 2.5 (PM2.5) and carbon dioxide (CO2) concentration on occupant satisfaction and work productivity. This study carried out a real-scale experiments in a meeting room with exposures of up to one hour. Indoor environment parameters, including air temperature, relative humidity, illuminance, and noise level, were controlled at a reasonable level. Twenty-nine young participants were participated in the experiments. Four mental tasks were conducted to quantitatively evaluate the work productivity of occupants and a questionnaire was used to access participants’ satisfaction. The Spearman correlation analysis and two-way analysis of variance were applied. It was found that the overall performance declined by 1% for every 10 μg/m3 increase in PM2.5 concentration. Moreover, for every 10% increase in dissatisfaction with air quality, productivity performance decreased by 1.1% or more. It should be noted that a high CO2 concentration (800 ppm) has a stronger negative effect on occupant satisfaction towards air quality than PM2.5 concentration in a non-ventilated room. In order to obtain optimal occupant satisfaction and work productivity, low concentrations of PM2.5 (<50 μg/m3) and CO2 (<700 ppm) are recommended.

Effect of concentration and duration of particulate matter exposure on the transcriptome and DNA methylome of bronchial epithelial cells.

Exposure to particulate matter (PM) from ambient air pollution is a well-known risk factor for many lung diseases, but the mechanism(s) for this is not completely understood. Bronchial epithelial cells, which line the airway of the respiratory tract, undergo genome-wide level changes in gene expression and DNA methylation particularly when exposed to fine (<2.5 µm) PM (PM2.5). Although some of these changes have been reported in other studies, a comparison of how different concentrations and duration of exposure affect both the gene transcriptome and DNA methylome has not been done. Here, we exposed BEAS-2B, a bronchial epithelial cell line, to different concentrations of PM2.5, and compared how single or repeated doses of PM2.5 affect both the transcriptome and methylome of cells. Widespread changes in gene expression occurred after cells were exposed to a single treatment of high-concentration (30 µg/cm2) PM2.5 for 24 h. These genes were enriched in pathways regulating cytokine–cytokine interactions, Mitogen-Activated Protein Kinase (MAPK) signaling, PI3K-Akt signaling, IL6, and P53. DNA methylomic analysis showed that nearly half of the differentially expressed genes were found to also have DNA methylation changes, with just a slightly greater trend toward overall hypomethylation across the genome. Cells exposed to a lower concentration (1 µg/cm2) of PM2.5 demonstrated a comparable, but more attenuated change in gene expression compared to cells exposed to higher concentrations. There were also many genes affected by lower concentrations of PM2.5, but not higher concentrations. Additionally, repeated exposure to PM2.5 (1 µg/cm2) for seven days resulted in transcriptomic and DNA methylomic changes that were distinct from cells treated with PM2.5 for only one day. Compared to single exposure, repeated exposure to PM2.5 caused a more notable degree of hypomethylation across the genome, though certain genes and regions demonstrated increased DNA methylation. The overall increase in hypomethylation, especially with repeated exposure to PM2.5, was associated with an increase in expression of ten–eleven translocation enzymes. These data demonstrate how variations in concentration and duration of PM2.5 exposure induce distinct differences in the transcriptomic and DNA methylomic profile of bronchial epithelial cells, which may have important implications in the development of both acute and chronic lung disease.

Decline in PM2.5 concentrations over major cities around the world associated with COVID-19

The COVID-19 started from Wuhan city in China, slowly spread across the globe after December 2019. Due to movement of people from one city to other cities, one country to other countries, infection spreads and COVID-19 became a pandemic. Efforts were made at local, regional and national levels to lockdown the movement of people and to keep infected one in quarantine or isolation to stop the spread of COVID-19. The traffic, market and small industries were closed, as a result pronounced decline in the concentrations of particulate matters (PM) were observed. Normally these sources contribute to the high concentrations of particulate matters (PM2.5) which represents air quality of a location. In this short communication, we present analysis of PM2.5 of major cities (New York, Los Angeles, Zaragoza, Rome, Dubai, Delhi, Mumbai, Beijing and Shanghai) around the world suffered severely with the COVID-19. Our analysis shows decline in PM2.5 concentration due to lockdown, mainly due to less movement of people to keep “social distancing” to control the spread of CORONA-19. The low concentrations of PM2.5 reflect the efforts made in the cities to curb the spread of infection, that improve air quality.

Short-term PM2.5 exposure and emergency hospital admissions for mental disease

Epidemiologic studies regarding the relationship between short-term exposure to particulate matter with a median aerodynamic diameter < 2.5 µm (PM2.5) and mental disease are limited. This study examined the effects of short-term exposure to PM2.5 on emergency admissions to the hospital for mental disease in Seoul, Korea.Data regarding 80,634 emergency admissions for mental diseases were collected from a nationally centralized healthcare claims database in Seoul during 2003–2013. Generalized linear models with climate variables were used to examine associations between short-term PM2.5 exposure and mental disease admissions. To comprehensively assess PM2.5 effects, we used single- and two-pollutant models, which considered other pollutants in combination with PM2.5.The relative risk (RR) of emergency admissions for mental disease was 1.008 (95% confidence interval, 1.001–1.015) for each 10 μg/m3 increase in 2-day average PM2.5 concentration. This effect persisted or became slightly stronger in the two-pollutant models that included carbon monoxide, nitrogen dioxide, ozone, or sulfur dioxide (RR, 1.01–1.021), but association appeared to be limited to individuals < 65 years of age. Significant association was estimated only during the warm season (RR, 1.021–1.023) in the two-pollutant models. The exposure–response curve was steeper at lower concentrations, suggesting that the risk of mental disease at lower concentrations of pm2.5 (0–30 µg/m3). PM2.5 was associated with increased admissions even when it was below the World Health Organization's Air Quality Guidelines (25 μg/m3), but the association was not statistically significant.Thus, based on the data from a large database, exposure to PM2.5 was associated with increases in emergency admissions for mental diseases, and this association was significant during the warm season. PM2.5 may even affect mental disease at levels below the current air quality guidelines. These results provide substantial insight regarding the effects of air pollutants and have important implications for policy makers.

Indoor Fine Particle (PM2.5) Pollution and Occupant Perception of the Indoor Environment During Summer of the First Passivhaus Certified Dwelling in Latin America

This study compares the only residential Passivhaus in Mexico (located in Mexico City) to a conventional building-practice home in terms of indoor environmental quality during summer, specifically indoor air quality (IAQ) and the occupants’ perceptions towards it. Temperature, relative humidity, carbon dioxide, and PM2.5 were monitored during May, June and July 2016 in the living room, bedroom and kitchen of each home. Simultaneous outdoor air measurements were collected from the local pollution monitoring network. Online surveys were used to obtain data on building-related illnesses; while occupant perception of IAQ and thermal comfort and occupant diaries helped to provide insights into occupant behavior. Results from this case study suggest that Passivhaus design strategies could help to protect building occupants from outdoor air pollution, based on the lower concentrations of PM2.5 that were found in the Passivhaus apartment compared to the external environment. This contrasted with the results of the control home where PM2.5 levels were higher than ambient levels. Whilst the results cannot be generalized, they do provide much needed evidence on the indoor environmental performance of a Passivhaus-certified dwelling in Latin America, highlighting areas for improvement and providing recommendations to help inform future developments adopting these principles in a subtropical highland climate.

Impacts of particulate matter (PM2.5) on the behavior of freshwater snail Parafossarulus striatulus

Fine particulate (PM2.5) is a severe problem of air pollution in the world. Although many studies were performed on examining effects of PM2.5 on human health, the understanding of PM2.5 influence on aquatic organisms is limited. Due to wet deposition, the pollutants in PM2.5 can enter aquatic ecosystems and affect aquatic organisms. This study tested the hypothesis that PM2.5 will negatively affect the behavior of freshwater snail Parafossarulus striatulus (Benson, 1842). Along with PM2.5, a number of components (Al, Pb, and Zn) that are commonly present in PM2.5 were also tested for their effects on the snail's behavior. The snail behavior was scored using the Behavioral State Score (BSS), ranging from 0 (no movement) to 5 (active locomotion and fully extended body). The result shows that high PM2.5 concentration dose (7.75 mg/L) induced a significant decrease in snails’ movement behavior, and such reduced movement. The same behavior was also observed for treatments with chemical components related to PM2.5, including aluminum and acidity (pH 5.0). In contrast, a low concentration of PM2.5 (3.88 mg/L), lead, and zinc did not significantly affect snails’ behavior. The results suggest that high PM2.5 deposition in water bodies, associated with acidification and some metals, can have an adverse effect on aquatic organisms.

Evaluation of the Effects of Airborne Particulate Matter on Bone Marrow-Mesenchymal Stem Cells (BM-MSCs): Cellular, Molecular and Systems Biological Approaches.

Particulate matter (PM) contains heavy metals that affect various cellular functions and gene expression associated with a range of acute and chronic diseases in humans. However, the specific effects they exert on the stem cells remain unclear. Here, we report the effects of PM collected from the city of Jeddah on proliferation, cell death, related gene expression and systems of biological analysis in bone marrow mesenchymal stem cells (BM-MSCs), with the aim of understanding the underlying mechanisms. PM2.5 and PM10 were tested in vitro at various concentrations (15 to 300 µg/mL) and durations (24 to 72 h). PMs induced cellular stress including membrane damage, shrinkage and death. Lower concentrations of PM2.5 increased proliferation of BM-MSCs, while higher concentrations served to decrease it. PM10 decreased BM-MSCs proliferation in a concentration-dependent manner. The X-ray fluorescence spectrometric analysis showed that PM contains high levels of heavy metals. Ingenuity Pathway Analysis (IPA) and hierarchical clustering analyses demonstrated that heavy metals were associated with signaling pathways involving cell stress/death, cancer and chronic diseases. qRT-PCR results showed differential expression of the apoptosis genes (BCL2, BAX); inflammation associated genes (TNF-α and IL-6) and the cell cycle regulation gene (p53). We conclude that PM causes inflammation and cell death, and thereby predisposes to chronic debilitating diseases.

Spatiotemporal dynamics of atmospheric PM2.5 and PM10 and its influencing factors in Nanchang, China

PM2.5 and PM10 have become the primary pollutants of most cities in China. Atmospheric PM2.5 and PM10 mass concentrations, meteorological factors, traffic flow from 2013 to 2015 in Nanchang were analyzed. Spatiotemporal dynamic pattern of atmospheric particulate matter pollution and the effect of weather and traffic on particle concentration change were discussed in this paper. The results showed that PM2.5(70.92 μg·m-3 in 2013 > 53.70 μg·m-3 in 2014 ＞ 43.65 μg·m-3 in 2015) and PM10(119.72 μg·m-3 in 2013 ＞ 86.11 μg·m-3 in 2014 ＞ 73.32 μg·m-3 in 2015) concentrations decreased gradually from 2013 to 2015. In addition, low concentrations of PM2.5 and PM10 in summer (average PM2.5 concentration 36.74 μg·m-3, average PM10 concentration 69.20 μg·m-3) but high concentrations in winter (average PM2.5 concentration 74.29 μg·m-3, average PM10 concentration 111.64 μg·m-3) were observed. Moreover, PM2.5 and PM10 concentrations changed with the urban-rural gradient, decreasing from the city center to suburb. The ratio of PM2.5/PM10(0.595 ＞ 0.584 ＞ 0.557) decreased year by year from 2013 to 2015 and was higher in the city center area than in the edge of city. PM2.5 and PM10 concentrations were affected by various meteorological factors and significantly related to air pressure, temperature, relative humidity, wind speed, precipitation and sunshine time. The influence of meteorological factors differed on PM2.5 and PM10 concentrations. Traffic flow significantly increased the surrounding PM2.5 concentration, but not PM10 concentration.

Spatiotemporal analysis of ambient air pollution exposure and respiratory infections cases in Beijing.

Ambient air pollutants (PM2.5) are components of persistent haze in Beijing during the autumn and winter seasons. We collected hourly PM2.5 monitoring data for 35 days from 35 sites in Beijing during 2012. We also identified patients developing respiratory infections during the same time period in the same locale. A BME model was used to simulate environmental exposure concentrations over the course of each day. A medical accessibility analysis was performed to exclude the impact of medical availability on the analysis. A spatial analysis was included in the evaluation of the relationship between exposure duration and concentration of PM2.5 with the development of acute respiratory disease. A low concentration of PM2.5 (greater than 35 µg/m3 and less than 115 µg/m3) for at least 3 days was associated with an increased risk of acute respiratory disease. A high concentration of PM2.5 (greater than 115 µg/m3) was associated with an increased risk of infection even after 1 day of exposure.

一次PM 2.5 过程及其主要成分的同化试验

利用大气化学模式WRF-Chem建立3D_Var同化系统,对美国西部地区一次PM2.5化学污染过程的PM2.5总量及其主要成分(黑碳、有机碳、硝酸盐、硫酸盐)进行了同化试验,并与未同化结果和实况进行了区域、单站及时间序列的对比。结果表明,此系统具有较好的同化效果,同化试验结果与实况接近,站点分布和演变趋势吻合较好;任取3个站点进行单点时间序列演变和散点分布分析,同化后相关系数有所增加,均在0.85以上,在所选3个站点中相关系数最大达0.95,均方根误差都明显减小;数值模拟没有模拟出的大值中心,但经同化后能再现出来;模式模拟PM2.5低浓度值的演变趋势及数值要好于高浓度值;随着模式的运行,同化前期效果最好,同化中期和后期结果与实况偏差有所增加;模式还存在系统偏差和奇点问题,这些是模式需要改进的地方。