Characteristics and fate behavior of environmentally persistent free radicals in atmospheric particulate matter

Background,aim,and scope Environmentally persistent free radicals(EPFRs)have received significant attention due to their longer lifetime and stable existence in various environments.The strong environmental migration ability of particulate matter allows EPFRs to migrate over long-distance transport,thereby impacting the quality of the local atmospheric environment.Additionally,EPFRs can also adhere to atmospheric particles and interact with typical gaseous pollutants to affect atmospheric chemical reactions.EPFRs can produce some reactive organic species,promoting oxidative stress in the human body,damaging biological macromolecules and ultimately affecting the organism health.EPFRs are considered as a novel type of pollutant that affects human health.Despite their significance,there are few literatures available on the characteristics and fate behaviors of EPFRs up to date.Therefore,supplemental reviews are crucial for providing comprehensive understanding of EPFRs.Materials and methods This review summarizes the characteristics of EPFRs in particulate matter,outlines the generation mechanism and influencing factors of EPFRs,and the impacts of EPFRs on environmental quality and organism health.Results The content of EPFRs in particulate matter ranges from 1017 to 1020 spins∙g−1.Due to the strong mobility of atmospheric particulate matter,the long-term exposure to high levels of EPFRs may aggravate the impact of particulate matter on human health.The interaction between EPFRs and typical gaseous pollutants can alter their fate and influence atmospheric chemical reactions.EPFRs are mainly produced by transition metal elements and substituted aromatic hydrocarbons through electron transfer.Additionally,the chemical bond rupture of organic substances through heat treatment or ultraviolet radiation can also produce EPFRs,and heterogeneous reactions are capable producing them as well.The production of EPFRs is not only influenced by transition metal elements and precursors,but also by various environmental factors such as oxygen,temperature,light radiation,and relative humidity.Discussion EPFRs in atmospheric particulates matters are usually rich in fine particulates with obvious seasonal and regional variations.They can easily enter the human respiratory tract and lungs with inhalable particulates,thereby increasing the risk of exposure.Additionally,EPFRs in atmospheric particulates can interact with some typical gaseous pollutants,impacting the life and fate of EPFRs in the atmosphere,and alter atmospheric chemical reactions.Traditionally,EPFRs are generated by transition metal elements and substituted aromatic hydrocarbons undergoing electron transfer in the post-flame and cool-zone regions of combustion systems and other thermal processes to remove HCl,H_(2)O or CO groups,ultimately produce semiquinones,phenoxyls,and cyclopentadienyls.Recent studies have indicated that EPFRs can also be generated under the conditions of without transition metal elemental.Organics can also produce EPFRs through chemical bond rupture during heat treatment or light radiation conditions,as well as through some heterogeneous reactions and photochemical secondary generation of EPFRs.The presence or absence of oxygen has different effects on the type and yield of EPFRs.The concentration,type,and crystal type of transition metal elements will affect the type,content,and atmospheric lifetime of EPFRs.It is generally believed that the impact of transition metal element types on EPFRs is related to the oxidation-reduction potential.The combustion temperature or heat treatment process significantly affects the type and amount of EPFRs.Factors such as precursor loading content,pH conditions,light radiation and relative humidity also influence the generation of EPFRs.EPFRs can interact with pollutants in the environment during their migration and transformation process in environmental medium.This process accelerates the degradation of pollutants and plays a crucial role in the migration and transformation of organic pollutants in environmental media.The reaction process of EPFRs may lead to the production of reactive oxygen species(ROS)such as∙OH,which can induce oxidative stress,inflammation and immune response to biological lung cells and tissues,leading to chronic respiratory and cardiopulmonary dysfunction,cardiovascular damage and neurotoxic effects,ultimately impacting the health of organisms.Conclusions The interaction mechanism between EPFRs in particulate matter and gaseous pollutants remains unclear.Furthermore,research on the generation mechanism of EPFRs without the participation of transition metals is not comprehensive,and the detection of EPFRs is limited to simple qualitative categories and lack accurate qualitative analysis.Recommendations and perspectives Further research should be conducted on the generation mechanism,measurement techniques,migration pathways,and transformation process of EPFRs.It is also important to explore the interaction between EPFRs in atmospheric particulate matter and typical gaseous pollutants.

Impact of Urban 3D Morphology on Particulate Matter 2.5(PM2.5) Concentrations:Case Study of Beijing, China

Urban particulate matter 2.5(PM2.5)pollution and public health are closely related,and concerns regarding PM2.5 are widespread.Of the underlying factors,the urban morphology is the most manageable.Therefore,investigations of the impact of urban three-dimensional(3D)morphology on PM2.5 concentration have important scientific significance.In this paper,39 PM2.5 monitoring sites of Beijing in China were selected with PM2.5 automatic monitoring data that were collected in 2013.This data set was used to analyze the impacts of the meteorological condition and public transportation on PM2.5 concentrations.Based on the elimination of the meteorological conditions and public transportation factors,the relationships between urban 3D morphology and PM2.5 concentrations are highlighted.Ten urban 3D morphology indices were established to explore the spatial-temporal correlations between the indices and PM2.5 concentrations and analyze the impact of urban 3D morphology on the PM2.5 concentrations.Results demonstrated that road length density(RLD),road area density(RAD),construction area density(CAD),construction height density(CHD),construction volume density(CVD),construction otherness(CO),and vegetation area density(VAD)have positive impacts on the PM2.5 concentrations,whereas water area density(WAD),water fragmentation(WF),and vegetation fragmentation(VF)(except for the 500 m buffer)have negative impacts on the PM2.5 concentrations.Moreover,the correlations between the morphology indices and PM2.5 concentrations varied with the buffer scale.The findings could lay a foundation for the high-precision spatial-temporal modelling of PM2.5 concentrations and the scientific planning of urban 3D spaces by authorities responsible for controlling PM2.5 concentrations.

Short-term exposure to fine particulate matter and hospital admission for stroke:a meta-analysis

Objective Air pollution is an important risk factor for cardiovascular diseases throughout the world.Fine particulate matter(PM)air pollution alone is responsible for over three million deaths each year.Large and growing literature has explored whether short-term exposure to fine particulate matter is associated with stroke,but results from prior studies have been inconsistent.To fill this gap,we assessed the evidence quantitatively from epidemiological time-series studies published worldwide and determined whether short-term exposure to fine particulate matter(<2.5μm or<10μm)diameter[PM2.5 and PM10]was associated with increased risk of hospital admission for stroke(including ischemic and hemorrhagic stroke).

Effect of Varying Temperature and Oxygen on Particulate Matter Formation in Oxy-Biomass Combustion

Offsetting particulate matter emissions has become a critical global aim as there are concerted efforts to deal with environmental and energy poverty challenges.This study consists of investigations of computing emissions of particulate matter from biomass fuels in various atmospheres and temperatures.The laboratory setup included a fixed bed electric reactor and a particulate matter(PM)measuring machine interfaced with the flue gas from the fixed bed reactor combustion chamber.The experiments were conducted at seven different temperatures(600℃-1200℃)and six incremental oxygen concentrations(21%-100%).Five biomass types were studied;A-cornstalk,B-wood,C-wheat straw,D-Rice husk,E-Peanut shell,each pulverized to a size of approximately 75 microns.The study shows that PM emitted during char combustion is consistently higher than that emitted during the de-volatilization.During de-volatilization,increase in temperature leads to linear decrease in PM emission between atmospheres of 21%O_(2)to 50%O_(2),thereafter,between 70%O_(2)to 100%O_(2);increase in temperature leads to a rise in PM emission.The average PM formation from all the five considered biomass is relatively comparable however,with differing atmospheres and temperatures,the fibrous and low-density biomass forms more PM.During char combustion,the study shows that at oxygen levels of 21%,70%,90%and 100%,increase in temperature leads to increased PM emission.The increase in oxygen concentration and temperature increases the rate of combustion hence diminishing the time of combustion.

A Study of the Correlation between the Concentration of Particulate Matter and Green Area Ratio Measured through a Portable Monitoring System: With Particular Focus on the Case of Dalseo-Gu, Daegu Metropolitan City

This study analyzed the relationship between the measured concentration of particulate matter (PM) and green area, which is an important spatial factor affecting urban PM concentration and even more carbon neutral in cities. In order to investigate the effects of green area, the green area ratio (GAR) is used and correlated with particulate matter. As a result of analyzing the correlation between GAR and PM concentration using the measured PM data, it was found that there was a positive correlation between the two variables. Hence, the higher the GAR, the lower the PM concentration. It can be said that the introduction of spatial elements with high GAR scores, such as parks and forests in cities, is effective in reducing PM concentration. In this study, a portable PM monitoring system using a vehicle for PM measurement was also established and operated. As a result, it was found that a PM monitoring system using a light-scattering sensor is an effective PM measurement method that can be used at the local government level. It was also found that a follow-up study is needed in the future to identify the PM mitigation functions of urban green areas according to the detailed characteristics of green areas as well as various environmental factors. This study can be used in air quality improvement activities and efforts as reference data by policy decision makers and in the field of environmental planning associated with the removal of airborne particulate matter pollution in urban areas.

Human Health Risks from Exposure to Heavy Metals of Suspended Particulate Matter around the Tongon Gold Mine, Côte d’Ivoire

The Tongon mine, the largest gold mine in C?te d’Ivoire, has been in operation since April 2010. However, to our knowledge to date, no study has been conducted on metallic contamination in suspended particulate matter (PM10 and PM2.5) where there is a lack of information on the carcinogenic and non-carcinogenic risk to human health associated with the exposure of populations in the Tongon area to these pollutants. The general objective of this study is to evaluate the level of contamination of PM10;PM2.5 by heavy metals and their impact on the health of populations exposed to these pollutants in the Tongon gold mine area. The sampling and measurement of suspended particulate matter (PM10 and PM2.5) were done using a MiniVol TAS passive air sampler. Heavy metal concentrations were determined by inductively coupled plasma mass spectroscopy (Nex ION 2000 ICP-MS, USA). The results indicate that the average concentrations of suspended particles (PM2.5 and PM10) obtained are all above the recommended exposure limits. In addition, among the heavy metals contained in the suspended particles, the concentrations of arsenic and nickel are high and all above the standard limit values. The assessment of the health risks related to the inhalation of PM10 particles reveals that their inhalation over a long period could cause a carcinogenic risk.

Spatial and Temporal Variation of Particulate Matter (PM10 and PM2.5) and Its Health Effects during the Haze Event in Malaysia

This study aims to assess and compare levels of particulate matter(PM10 and PM2.5)in urban and industrial areas in Malaysia during haze episodes,which typically occur in the south west monsoon season.The high concentrations of atmospheric particles are mainly due to pollution from neighbouring countries.Daily PM concentrations were analysed for urban and industrial areas including Alor Setar,Tasek,Shah Alam,Klang,Bandaraya Melaka,Larkin,Balok Baru,and Kuala Terengganu in 2018 and 2019.The analysis employed spatiotemporal to examine how PM levels were distributed.The data summary revealed that PM levels in all study areas were right-skewed,indicating the occurrence of high particulate events.Significant peaks in PM concentrations during haze events were consistently observed between June and October,encompassing the south west monsoon and inter-monsoon periods.The study on acute respiratory illnesses primarily focused on Selangor.Analysis revealed that Klang had the highest mean number of inpatient cases for acute exacerbation of bronchial asthma(AEBA)and acute exacerbation of chronic obstructive pulmonary disease(AECOPD)with values of 260.500 and 185.170,respectively.Similarly,for outpatient cases of AEBA and AECOPD,Klang had the highest average values of 41.67 and 14.00,respectively.Shah Alam and Sungai Buloh did not show a significant increase in cases during periods of biomass burning.The statistical analysis concluded that higher concentrations of PM were associated with increased hospital admissions,particularly from June to September,as shown in the bar diagram.Haze episodes were associated with more healthcare utilization due to haze-related respiratory illnesses,seen in higher inpatient and outpatient visits(p<0.05).However,seasonal variability had minimal impact on healthcare utilization.These findings offer a comprehensive assessment of PM levels during historic haze episodes,providing valuable insights for authorities to develop policies and guidelines for effective monitoring and mitigation of the negative impacts of haze events.

Indoor and Outdoor Particulate Matter Exposure of Rural Interior Alaska Residents

To assess the exposure of residents in rural communities in the Yukon Flats to particulate matter of 2.5 μm or less in diameter (PM2.5), both indoor and outdoor concentration observations were carried out from March to September 2019 in Ft. Yukon, Alaska. Indoor concentrations were measured at 0.61 m (breathing level during sleeping) in homes and at 1.52 m heights (breathing level of standing adult) in homes and office/commercial buildings. Air quality was better at both heights in cabins than frame homes both during times with and without surface-based inversions. In frame houses, concentrations were higher at 0.61 m than 1.52 m, while the opposite is true typically for cabins. Differences between shoulder season and summer indoor concentrations in residences were related to changes in heating, subsistence lifestyle and mosquito repellents. In summer, office and commercial buildings, air quality decreased due to increased indoor emissions related to increased use of equipment and mosquito pics as well as more merchandise. During summer indoor concentrations reached unhealthy for sensitive groups to hazardous conditions for extended times that even exceeded the high outdoor concentrations. Due to nearby wildfires, July mean outdoor concentrations were 55.3 μg·m-3 which exceeds the 24-h US National Ambient Air Quality Standard of 35 μg·m-3. Indoor and outdoor concentrations correlated the strongest with each other for office/commercial buildings, followed by frame houses and cabins. Office/commercial buildings with temperature monitors had one to two orders of magnitude lower concentrations than those without.

Mineralogical characterization of airborne individual particulates in Beijing PM10

This work mainly focuses on the mineralogical study of particulate matter（PM10） in Beijing. Samples were collected on polycarbonate filter from April, 2002 to March, 2003 in Beijing urban area. Scanning electronic microscopy coupled with energy dispersive X-ray（SEM/EDX） was used to investigate individual mineral particles in Beijing PM10. 1454 individual mineral particulates from 48 samples were analysed by SEM/EDX. The results revealed that mineral particulates were complex and heterogeneous. 38 kinds of minerals in PM10 were identified. The clay minerals, of annual average percentage of 30.1%, were the main composition among the identified minerals, and illite/smectite was the main composition in clay minerals, reaching up to 35%. Annual average percentage of quartz, calcite, compound particulates, carbonates were 13.5%, 10.9%, 11.95%, 10.31%, respectively. Annual average percentage less than 10% were gypsum, feldspar, dolomite, and so on. Fluorite, apatite, halite, barite and chloridize zinc（ZnCl2） were firstly identified in Beijing PM10. Sulfurization was found on surface of mineral particles, suggested extensive atmospheric reaction in air during summer.

基于机器感知与学习的空气颗粒物智能检测、识别与预警方法研究综述

随着空气污染问题的不断加剧,准确检测和及时预警空气颗粒物(particulate matter,PM)的重要性日益突出。传统方法依赖专业设备,不适用于实时检测。与传统方法相比,基于机器感知与学习的方法体现出技术优势,具有可实时检测、准确性高等优点。因此,对近几年的基于机器感知与学习的PM智能检测、识别与预警方法进行详细综述。首先,对PM的标准和来源进行介绍;然后,从检测、识别和预警这3个方面详细总结了各类方法,并对比各方法的特点和性能,其中,基于机器学习和深度学习的方法在各研究中取得了较大进展;最后,总结全文主要内容,并提出当前领域面临的挑战以及未来的重点研究方向。未来的研究应该继续关注技术创新和数据质量,以实现更好的空气质量监测和管理。

富马酸二甲酯通过Nrf2/HO-1信号通路缓解细颗粒物对雌性大鼠胎盘的氧化损伤

近年来,已有大量的流行病学调查证实,孕产妇暴露于PM_(2.5)可能导致妊娠并发症和不良妊娠结局的风险增加。本研究旨在探讨孕前PM_(2.5)暴露对大鼠胎盘的损伤及富马酸二甲酯(dimethyl fumarate,DMF)对其调控机制。40只6周龄SPF级雌性SD大鼠,随机分为对照组(生理盐水)、低剂量PM_(2.5)组(1.5 mg/kg PM_(2.5))、高剂量PM_(2.5)组(7.5 mg/kg PM_(2.5))、DMF对照组(生理盐水+50 mg/kg DMF)和DMF干预组(7.5 mg/kg PM_(2.5)+50 mg/kg DMF)。大鼠每2 d染毒1次,共持续40 d。经PM_(2.5)暴露后,高剂量PM_(2.5)组胎鼠数量、胎鼠平均体长、超氧化物歧化酶(SOD)活性和总抗氧化能力(T-AOC)、白细胞介素-10(IL-10)含量明显低于对照组(P<0.05);丙二醛(MDA)含量高于对照组(P<0.05);经DMF处理后,DMF干预组的T-AOC含量显著高于高剂量PM_(2.5)组(P<0.01),能够明显缓解PM_(2.5)诱导的氧化损伤作用。H&E染色结果显示,暴露组胎盘组织迷路区血细胞有不同程度的减少,高剂量PM_(2.5)组血管脉络不清晰,DMF干预组胎盘迷路区的血细胞明显增多,血管脉络清晰整齐。Western印迹结果显示,低剂量PM_(2.5)组和高剂量PM_(2.5)组核因子E2相关因子(Nrf2)、血红素加氧酶1(HO-1)蛋白质水平低于对照组(P<0.01),与高剂量PM_(2.5)组相比,DMF干预组的Nrf2、HO-1蛋白质含量明显增高(P<0.05)。综上所述,DMF可能通过Nrf2/HO-1信号通路缓解孕前PM_(2.5)对胎盘造成的氧化损伤,提高机体的抗氧化能力。

一般通风用空气过滤器标准ISO 16890应用探究

《一般通风用空气过滤器》国际标准ISO16890:2016基于颗粒物对人类健康的影响,提出按|照颗粒物不同粒径范围(PM1PM25,PM10)的过滤效率对空气过滤器进行测试和分级。以及通过和其他一般通风用空气过滤器标准的对比分析,说明ISO16890与其他标准之间的差异。并提出美埃执行ISO16890的实施方案。

燃煤电厂烟气湿度控制对颗粒物采样结果的影响研究

为探究超低排放改造后燃煤电厂高湿烟气对低浓度颗粒物采样结果的影响,利用扩散干燥管控制湿度,可降低因蒸气凝结而产生的颗粒物转移损失。在实验室搭建烟气发生装置模拟电厂高湿烟气,研究相对湿度对低浓度颗粒物测量结果的影响,并对循环流化床燃煤电厂高湿烟气中低浓度颗粒物进行现场测试。结果表明,在电厂使用常规采样方法采集到的TSP、PM10和PM2.5质量浓度分别为2.73 mg/m^(3)、2.18 mg/m^(3)和1.69 mg/m^(3),控制烟气相对湿度在95.1%~96.4%后,所采集到的TSP、PM10和PM2.5质量浓度分别为相对湿度98.2%时的1.36~1.65倍、1.24~1.96倍和1.03~2.20倍。水溶性离子NH_(4)^(+)、Cl^(-)、SO_(4)^(2-)为采样电厂颗粒物中主要组成部分,约占总离子数的88.3%~99.7%。经扩散干燥管控制湿度后,采集到的颗粒物中TSP、PM_(10)和PM_(2.5)水溶性离子总质量浓度分别为采用传统方法时的1.72倍、1.82倍和1.74倍。实验证明了燃煤电厂颗粒物采样中使用扩散干燥管控制烟气湿度可降低凝结损失,提高颗粒物的采集效率和测定结果的准确性。

基于β射线法的新型PM2.5自动监测系统研究

近年来大颗粒物污染日趋严重,准确监测颗粒物PM2.5迫在眉睫。目前国外监测仪器已在国际上普遍使用,国内真正的知识产权产品比较少,产品的精度以及稳定性也有待提高。采用基于β射线法原理研制了PM2.5质量浓度在线监测系统,在仪器结构中提出采用原位检测的方法,并进行与标准称重法的比对实验来验证系统的可行性,结果表明两者测量数据的相关性为0.988。通过数据校正补偿后与监控站赛默飞仪器比对实时监测数据,日测量数据平均值相对偏差仅为1.8%。

卫星遥感监测近地表细颗粒物多元回归方法研究

对地基监测PM2.5和气象数据、MODISAOD卫星数据与NCEP FNL数据进行了处理分析,在与一元简单线性模型(模型1)进行对比的基础上,建立了适应于北京及其附近地区遥感监测近地面颗粒物(PM2.5)浓度的多元线性(模型2)和非线性(模型3)回归模型,并对模型进行了评价验证和遥感监测初步应用.结果表明:模型1,2,3分别能够解释PM2.5 32.5%,56.1%,62.7%的变异.反演的PM2.5浓度与站点监测值相关性分别为0.5488(R2=0.3012),0.7449(R2=0.5549),0.7431(R2=0.5523).对于站点监测PM2.5浓度63.1652μg/m3的均值,反演均方根误差RMSE分别为43.5562,35.3321,36.8450μg/m3.模型2和3中气象因子分别能够解释PM2.5 23.6%和12.6%的变异,说明了气象因子影响北京地区春季PM2.5-AOD关系的显著性.3种模型整体上都不同程度地存在着低值高估和高值低估的现象.

水泥窑PM_(2.5)排放特性及其PAHs风险分析

采用荷电低压颗粒物撞击器(ELPI)、便携式PM2.5采样器和稀释系统,对国内3家新型干法水泥生产厂(5条生产线)的水泥窑(包括窑头和窑尾)进行现场采样,分析水泥窑排放PM2.5的质量浓度、粒数浓度及其中的多环芳烃(PAHs)浓度,对呼吸致癌风险进行评价.结果表明:从粒数浓度分析,PM2.5中70%以上为PM0.33,这部分颗粒物主要是由气化凝结形成的.各采样点排放的PAHs主要以二环和三环的低环PAHs为主.第3个水泥厂窑头排放的PAHs含量最高,而且苯并[a]芘(BaP)超过国家所规定的8ng/m3标准限值,同时其呼吸致癌风险水平为4.46×10-4,高于可接受致癌风险水平的上限,需要有效处理.

燃煤锅炉PM2.5控制现状及改进建议

燃煤锅炉消耗大量煤炭,对大气环境中PM 2.5含量影响很大。对燃煤锅炉PM 2.5的治理是一个综合治理的过程,即包含一次可过滤颗粒物和一次可凝结颗粒物的治理,也包含对二次颗粒物前驱物SO2、NOx等的治理。本文从一次颗粒物和二次颗粒物治理角度,论述了燃煤锅炉PM 2.5的产生、控制现状,提出了PM 2.5控制技术的改进建议。

保护性耕作综合效益评价体系构建及实例分析

保护性耕作是防治农田土壤风蚀起尘的重要技术方法之一,对于从源头上控制颗粒物污染有重要作用。为了综合评价保护性耕作技术的生态环境效益、社会效益和经济效益,该研究构建了一个包含3个一级评价指标、8个二级评价指标、19个三级评价指标的综合效益评价指标体系,并以天津市大港区苏家园村为例,对传统耕作、免耕覆盖、深松耕3种耕作方式下的生态、经济、社会及综合效益进行评价,以验证评价指标体系的可行性。结果表明:从生态环境效益方面来看,传统耕作<免耕覆盖<深松耕,其指标值分别为0.182、0.540、0.875;从综合效益来看,传统耕作<深松耕<免耕覆盖,其指标值分别为0.279、0.435、0.584。保护性耕作比传统耕作具有更高的生态环境和综合效益。该研究可为合理地评价保护性耕作综合效益提供参考,对发展保护性耕作起到良好的导向作用。

北京城6区大气颗粒物质量浓度变化规律研究

为较好地了解当前北京城6区大气颗粒物PM_(2.5)和PM_(10)质量浓度的污染水平及变化规律,根据2013年3月11日至2014年2月28日城6区12个空气质量实时监测点连续、实时的监测结果,构建多点位、完整时间序列的颗粒物质量浓度数据资料。应用数理统计分析手段,对当前北京城6区大气颗粒物质量浓度的频数分布、相关性和逐时变化特征进行分析,并结合全年实际气象特征,对引起大气颗粒物质量浓度变化的因素进行了初步探讨。结果表明,2013年3月至2014年2月北京城6区大气颗粒物污染较为严重,且PM_(2.5)和PM_(10)质量浓度具有特别显著的线性相关关系,全年相关系数达0.9,10年间无显著变化;二者年均值达91.7μg/m^3和116.9μg/m^3,分别超标162%和67%;二者质量浓度比达78.4%,10年间同比增长约20%。颗粒物质量浓度逐时变化受季节变化影响明显,总体呈现夜间最高、白天最低的趋势,变化周期为7~9 h。研究表明,影响颗粒物质量浓度变化的因素包括春季的大风和生物粒子、夏季的湿热和降雨、秋季和冬季的逆温现象和降雪等气象因素及规律性的人为源因素。

Antagonistic Effects of N-acetylcysteine on Mitogen-activated Protein Kinase Pathway Activation, Oxidative Stress and Inflammatory Responses in Rats with PM2.5 Induced Lung Injuries

Objective To evaluate the antagonistic effects of N-acetylcysteine(NAC)on mitogen-activated protein kinases(MAPK)pathway activation,oxidative stress and inflammatory responses in rats with lung injury induced by fine particulate matter(PM2.5).Methods Forty eight male Wistar rats were randomly divided into six groups:blank control group(C1),water drip control group(C2),PM2.5 exposed group(P),low-dose NAC treated and PM2.5 exposed group(L),middle-dose NAC treated and PM2.5 exposed group(M),and high-dose NAC treated and PM2.5 exposed group(H).PM2.5 suspension(7.5 mg/kg)was administered tracheally once a week for four times.NAC of 125 mg/kg,250 mg/kg and 500 mg/kg was delivered intragastrically to L,M and H group respectively by gavage(10 ml/kg)for six days before PM2.5 exposure.The histopathological changes and human mucin 5 subtype AC(MUC5AC)content in lung tissue of rats were evaluated.We investigated IL-6 in serum and bronchoalveolar lavage fluid(BALF)by Enzyme-linked immunosorbent assay(ELISA),MUC5AC in lung tissue homogenate by ELISA,glutathione peroxidase(GSH-PX)in serum and BALF by spectrophotometry,and the expression of p-ERK1/2,p-JNK1/2 and p-p38 proteins by Western blot.All the measurements were analyzed and compared statistically.Results Lung tissue of rats exposed to PM2.5 showed histological destruction and increased mucus secretion of bronchial epithelial cells.Rats receiving NAC treatment showed less histological destruction and mucus secretion.Of P,L,M and H group,MUC5AC in lung tissue,IL-6 in serum and BALF were higher than controls(C1 and C2)(all P<0.05),with the highest levels found in the P group and a decreasing trend with increase of NAC dose.The activity of GSH-PX in serum and BALF of PM2.5 exposed rats(P,L,M and H)was lower than that of controls(all P<0.05),with higher activities found in NAC treated rats(L,M,and H),and an increasing trend with increase of NAC dose.The expressions of p-ERK1/2,p-JNK1/2 and p-p38 proteins in PM2.5 exposed lung tissue(P,L,M and H)was higher than controls(all P<0.05),with decreased levels and dose dependent downregulation found in NAC treated rats.Conclusion NAC can antagonize major MAPK pathway activation,lung oxidative stress and inflammatory injury induced by PM2.5 in rats.