Thermal decomposition pathways for peroxyacetyl nitrate (PAN): Implications for atmospheric methyl nitrate levels

The unimolecular decomposition pathways of peroxyacetyl nitrate (PAN) have been investigated in the presence of added NO₂ over the temperature range 298–345 K. The major products of the PAN decomposition were CO₂ and, depending on the ratio of O₂ to NO₂ in the experiment, either CH₂O or methyl nitrate. From the observed PAN decay rates and product yields, upper limits for the direct formation of either NO₃ or methyl nitrate from the unimolecular decay of PAN were obtained. The results indicate that these channels occur with rate constants that are thousands of times slower than dissociation of PAN into peroxyacetyl and NO₂, and that PAN decomposition is not a significant source of atmospheric methyl nitrate.     

Sulfur dioxide,hydrogen sulfide,total reduced sulfur,chlorinated hydrocarbons and photochemical oxidants in southern California museums

Indoor and outdoor concentrations of the air pollutants ozone, NO₂, SO₂, H₂S, total reduced sulfur (TRS), peroxyacetyl nitrate (PAN), methyl chloroform and tetrachloroethylene, have been measured at three southern California museums. Indoor maxima were 175 ppb for NO₂, 77 ppb for O₃, 0.7 ppb for PAN, 1.2 ppb for C₂Cl₄, >6.3 ppb for CH₃CCl₃, 2.5 ppb for SO₂, 1.4 ppb for TRS, and 46 ppt for H₂S. Indoor levels and indoor/outdoor (I/O) ratios for the chlorinated hydrocarbons pointed out to indoor sources. Outdoor and indoor levels of SO₂ and TRS were low at all three museums, but I/O ratios for SO₂ were high and averaged 0.89. H₂S concentrations were low, 16–46 ppt at one museum and less than 6 ppt at the other two museums. I/O ratios for the air pollutants with outdoor sources (ozone, PAN and NO₂) showed substantial variations, from low values of 0.02–0.33 at locations without influx of outdoor air to high values of 0.85–0.88 at locations experiencing high influx of outdoor air. Of the 10 institutions we have surveyed in southern California to date, eight exhibit high I/O ratios, e.g. 0.60–1.00 for PAN. Of the four museums surveyed that were equipped with HVAC and chemical filtration, only two yielded the expected low I/O ratios.     

Dynamic calibration of peroxyacetyl nitrate (PAN) analysers by annular denuder and ion-chromatographic techniques

Peroxyacetyl nitrate (PAN) at ppb-ppt levels is produced by irradiating a mixture of acetaldehyde and NO₂ dynamically generated by permeation tubes. The quantitative and selective removal of NO₂ and ozone from the reaction mixture performed by using two annular denuders allows the quantification of PAN as nitrite by ion chromatography carried out on the hydrolysed sample. The method is suitable for the field calibration of GC-based PAN-analysers.     

成都市降水对大气污染物的清除效果分析

成都市受特殊地形和气候条件影响,地面风速小,静风比例高,空气湿度大,大气污染物扩散缓慢,主要靠降水的冲刷和清除作用去除大气污染物.利用2014年5月13日-2017年12月31日成都市逐小时ρ（PM_2.5）、ρ（PM₁₀）、ρ（NO₂）、ρ（O₃）、ρ（CO）、ρ（SO₂）监测数据和同期地面降水量观测数据,分析了降水前污染物质量浓度、小时最大降水量、降水持续时间及累积降水量对大气污染物清除效果的影响.结果表明:①降水对6种大气污染物的清除率随降水前污染物质量浓度的增加而增大,并且汛期降水对大气污染物的清除率大于非汛期降水.②降水对大气污染物起正清除作用,清除率随降水持续时间的增加而增大.③不同降水量对不同污染物的清除效果不同,对PM_2.5、PM₁₀、NO₂、CO和SO₂的清除率随降水量的增加而逐渐增大,对O₃的清除效果相差不大且清除率均较大;小时最大降水量对PM_2.5、PM₁₀、NO₂、O₃、CO、SO₂的清除率平均值分别为29.48%、26.95%、22.02%、26.87%、11.94%、28.75%,累积降水量的清除率平均值分别为31.64%、30.66%、24.38%、26.31%、13.89%、32.91%,其中CO不易溶于水,降水对其清除作用明显小于其他几种污染物.研究显示,降水对大气污染物的清除作用显著,对SO₂、PM_2.5和PM₁₀的清除效果较好,而对CO的清除效果较差.      

Southern California air quality study: A search for methyl nitrate

Methyl nitrate, CH₃ONO₂, was measured by electron capture gas chromatography (EC-GC) under conditions which allowed resolution of methyl nitrate, PAN, and several chlorinated hydrocarbons. Calibrations involved both EC-GC andNO_x chemiluminescence and were in agreement with independent calibrations involving i.r. spectroscopy. The rate constant for photolysis of methyl nitrate in sunlight was< 2.3 × 10⁻⁶s⁻¹. Detection limits of field instruments were 0.1–0.4 ppb. Some 3000 EC-GC chromatograms grams of ambient air recorded between June and December 1987, during the Southern California Air Quality Study (SCAQS) at up to nine Southern California locations yielded only seven possible, but unlikely observations of methyl nitrate. Thus, methyl nitrate was only a minor component among nitrogenous air pollutants during SCAQS. The measured CH₃ONO₂/PAN ratios of<0.003–0.2 during SCAQS are discussed in terms of available kinetic data for PAN unimolecular decomposition (a major source of methyl nitrate), PAN thermal decomposition and CH₃ONO₂ photolysis.     

Nitrogenous air pollutants at a southern California mountain forest smog receptor site

Ambient levels of the nitrogenous pollutants NO, NO₂, nitric acid, nitrous acid, ammonia, particulate nitrate, particulate ammonium, peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) have been measured at a southern California mountain forest location severely impacted by urban photochemical smog. Air quality at the mountain forest location was characterized by high levels of nitric acid (up to 18 ppb) and the phytotoxic peroxyacyl nitrates PAN (up to 22 ppb) and PPN (up to 5 ppb). Alkyl nitrates were below our detection limits of 0.05–0.5 ppb. The (PAN + PPN)/NO₂ ratios varied substantially (range 0.03–2.27) and were generally large, with typical 24-h averages of 0.19–0.50. Diurnal variations of the (PAN/PPN)/NO₂ ratio exhibited both nighttime and daytime maxima reflecting diurnal variations in PAN (and PPN) thermal stability and photochemical production rates, respectively. Organic nitrogen-containing oxidation products (PAN + PPN) were more abundant than inorganic nitrate (HNO₃ + NO₃⁻), with an average organic/inorganic concentration ratio of 2.5 (daytime ratio 1.0; nighttime ratio 3.7). The four oxidation products PAN, PPN, HNO₃ and NO₃⁻ together accounted for 0.26 of the total reactive nitrogen. The results are discussed with respect to diurnal and seasonal variations and in terms of NO₂ atmospheric oxidation pathways. Deposition fluxes and velocities to ponderosa pine have been measured for inorganic nitrate and for ammonium and have been compared with those obtained at other mountain forest locations.     

车载激光雷达对北京地区边界层污染监测研究

介绍了自行研制的车载差分激光雷达AML-2探测原理及技术参数,于2006-08、2006-09在不同天气因素条件下对北京西南郊榆垡地区大气边界层污染物O3、NO2、SO2进行了实时监测,对比分析了3种污染物浓度垂直分布及日变化特征.结果表明,无外来污染输送时,3种污染物在阴雨天气总体浓度较小,O3和NO2浓度随高度升高而减小,SO2浓度垂直分布少见此特征,但在近地面0.6 km左右有较强SO2污染层.南部气流输送对北京地区大气环境影响明显,2006-08-23～2006-08-25这次强污染气流输送高度约1～1.5 km,3种污染物浓度垂直分布及日变化特征受到干扰,北京榆垡地区边界层O3、NO2、SO2总体浓度明显上升.     

A denuder technique for the measurement of nitrous acid in urban atmospheres

A new denuder set-up for the measurement of nitrous acid in polluted atmospheres is described here. The set-up is composed of one tetrachloromercurate-coated denuder for the removal of SO₂ and two downstream sodium carbonate-coated denuders for the determination of nitrous acid by the differential technique [Febo et al., 19, 1517–1530 1990]. The removal of SO₂ is necessary in order to avoid the formation of artifact nitrite on the sulfite layer which results from the interaction between atmospheric SO₂ and the Na₂CO₃ coating. Because of this mechanism, the measurement of HONO by means of the previously used NaClNa₂CO₃Na₂CO₃ denuder set-up is heavily biased in all cases when SO₂ and NO₂ are present at high concentration levels (e.g. urban environments).     

气候变化对浙江省大气污染的影响

开展气候变化对大气污染影响的研究有利于加深对大气污染形成机理的认识.利用1996-2015年浙江省大气成分、气象观测资料,分析气候变化对大气污染的影响.结果表明,近20 a来浙江省呈年高压天气日数增多、年均气温升高、降水集中及年均净辐射、日照时数、风速、气温日较差和水汽蒸发量都下降的气候变化事实.气候变化引起大气污染扩散能力下降,1996-2015年杭州市和浙江省年均大气扩散指数分别下降了0.55和0.81,降幅分别达35.71%和42.69%.大气扩散指数与ρ（PM₁₀）、ρ（PM_2.5）及年霾日数之间呈显著负相关,当大气扩散指数增大时,大气颗粒物浓度和年霾日数均下降,反之亦然.杭州市大气扩散指数与ρ（PM₁₀）、ρ（PM_2.5）之间的相关系数分别为0.73和0.76.杭州市和浙江省大气扩散指数与年霾日数之间的相关系数分别达到0.77和0.78,T检验值则分别为28.88和30.81,说明由气候变化引起的大气扩散能力改变是影响大气污染的重要原因,但不同大气成分受气候变化的影响程度不同.影响ρ（PM₁₀）的关键气候要素是降水量、风速及相对湿度等,影响ρ（PM_2.5）的主要是辐射、气温,影响ρ（SO₂）的主要是气温,影响ρ（NO₂）及ρ（NO₃-）、ρ（NH₄+）的主要是辐射.总体来说,浙江省近20 a的气候变化事实可能有利于促进ρ（PM₁₀）、ρ（PM_2.5）、ρ（NO₂）及ρ（O₃）等上升,促进ρ（SO₂）、ρ（NO₃-）、ρ（SO₄2-）、ρ（NH₄+）等下降.      

Effectiveness of national air pollution control policies on the air quality in metropolitan areas of China

Understanding the effectiveness of national air pollution controls is important for control policy design to improve the future air quality in China. This study evaluated the effectiveness of major national control policies implemented recently in China through a modeling analysis. The sulfur dioxide （SO2） control policy during the llth Five Year Plan period （2006-2010） had succeeded in reducing the national SO2 emission in 2010 by 14% from its 2005 level, which correspondingly reduced ambient SO2 and sulfate （SO42-） concentrations by 13%-15% and 8%-10% respectively over east China. The nitrogen oxides （NOx） control policy during the 12th Five Year Plan period （2011-2015） targets the reduction of the national NOx emission in 2015 by 10% on the basis of 2010. The simulation results suggest that such a reduction in NOx emission will reduce the ambient nitrogen dioxide （NO2）, nitrate （NO3-）, 1-hr maxima ozone （03） concentrations and total nitrogen deposition by 8%, 3%-14%, 2% and 2%--4%, respectively over east China. The application of new emission standards for power plants will further reduce the NO2, NO3-, 1-hr maxima 03 concentrations and total nitrogen deposition by 2%-4%, 1%-%, 0-2% and 1%-2%, respectively. Sensitivity analysis was conducted to evaluate the inter-provincial impacts of emission reduction in Beijing-Tianjin-Hebei and the Yangtze River Delta, which indicated the need to implement joint regional air pollution control.     

关中盆地NO2和SO2对颗粒物污染的协同效应

基于WRF-Chem模式模拟了关中盆地2019年1月2—14日一次颗粒物污染事件,评估了NO_x和SO₂减排及其在颗粒物污染中的协同作用对PM_2.5污染的影响。敏感性实验结果表明：NO_x减排可使PM_2.5中硝酸盐含量下降,但大气中O₃浓度上升,大气氧化能力增强,其他二次组分上升,导致PM_2.5下降不明显;SO₂人为源减排可使硫酸盐质量浓度下降,但由于硫酸盐在PM_2.5中占比较低,当SO₂减排75%时,PM_2.5仅下降1.74%;当减排比例较高时,NO_x和SO₂同时减排更有利于颗粒物污染防治。PM_2.5质量浓度在NO_x和SO₂同时减排75%时比分开减排75%时多下降0.75%,主要是硫酸盐下降所致;对气溶胶含水量进行分析,发现NO_x<...     

唐山市2017年采暖期不同污染等级PM2.5化学组分特征对比与来源分析

为深入了解唐山市采暖期PM_2.5污染成因与来源,采用在线监测设备于2017年12月1日-2018年1月28日连续监测了唐山市PM_2.5及其水溶性离子和碳质组分（OC、EC）的质量浓度变化,并结合部分常规气体污染物及气象数据进行对比分析.结果表明:①相对湿度的增加和风速的降低促进了污染的发展.②清洁、轻中度污染和重污染时,SOR（硫氧化率）分别为0.05、0.08、0.20,NOR（氮氧化率）分别为0.05、0.12、0.26,随着污染的加重,SO₂、NO_x向PM_2.5中SO₄2-、NO₃-的二次转化现象更加明显.③清洁时,ρ（OC）、ρ（EC）、ρ（SO₄2-）和ρ（Cl-）占PM_2.5化学组分（水溶性离子、碳质组分）质量浓度总和的68%,主要污染源为燃煤;清洁、轻中度污染和重污染时,ρ（NO₂）/ρ（SO₂）分别为0.96、1.14、1.44,ρ（NO₃-）/ρ（SO₄2-）分别为0.94、1.57和1.75;重污染时,ρ（SO₄2-）、ρ（NO₃-）、ρ（NH₄+）三者之和占PM_2.5化学组分质量浓度总和的61%,二次污染物成为主要污染源.④观测期,唐山市轻中度污染和重污染时,受经北京市、天津市等唐山市西部地区方向气团影响频率分别为61%、63%,受该方向气团影响时,ρ（NO₂）/ρ（SO₂）、ρ（NO₃-）/ρ（SO₄2-）明显增大.研究显示,相较于燃煤排放物在大气污染物中的占比变化,随着污染的加重,工业工艺和机动车尾气排放产生的污染物占比明显增大,区域传输对大气污染影响不可忽略,政府有必要开展区域联防联控、停产限产和限行限号的措施.      

沈阳及周边城市大气细粒子的分布特征及其对空气质量的影响

利用沈阳、鞍山、抚顺和本溪4城市2007-2009年大气细粒子PM2.5及大气污染物PM10SO2、NO2的观测资料,分析了4城市大气细粒子的分布特征及其与空气质量的关系.结果表明:4城市大气细粒子PM2.5污染很重,年均浓度平均值超过美国大气细粒子PM2.5年均浓度标准4倍左右;4城市PM10、SO2的年均浓度呈下降...     

南昌市固定燃烧点源大气污染物排放清单及特征

大气污染物排放清单是了解区域污染物排放特征、准确模拟空气质量的重要资料,而工业点源是大气污染的重点排放源.通过收集相关活动水平信息和合理的排放因子,采用"自下而上"的方法建立了南昌市2014年点源大气污染物排放清单.结果表明,SO_2、NO_x、CO、PM_(10)、PM_(2.5)和VOC排放总量分别为29576.2、17115.1、25946.6、4689.4、922.9和1190.4 t,其中,金属炼制行业对SO_2、CO和VOC的贡献最高,分别占37.75%、30.59%和38.45%;火电行业是NO_x的主要来源,其贡献率为47%;水泥等建材制造行业对PM_(10)和PM_(2.5)排放贡献最高,分别为26%和25%.根据排放源污染物排放量及地理坐标信息,建立了0.4 km×0.4 km的污染物排放量空间分布特征图,结果表明,南昌市大气污染物排放较为集中,青山湖区北部和新建区北部是SO_2、NO_x、CO和VOC的主要排放区,而PM_(10)和PM_(2.5)的排放量相对分散,并在安义县出现排放高值区.通过将计算结果与统计数据结果进行对比,了解所估算清单的准确程度.对SO_2和NO_x的计算值和统计值进行统计分析,结果显示,NMB(标准化平均偏差)和NME(标准化平均误差)值均小于50%,清单计算精度较高.同时,为了解清单数据质量,对清单的不确定性进行定量分析,结果显示,SO_2和VOC不确定性较低而PM_(10)和PM_(2.5)的不确定性相对较高,清单整体不确定性与其他研究结果相差不大.建议后期研究可以从提升基础数据质量和建立具有区域代表性的排放因子数据库着手,从而减小排放量的不确定性,获得精准可靠的大气污染物清单并应用于空气质量模型预报等更深入的研究.     

Wintertime peroxyacetyl nitrate (PAN) in the megacity Beijing: Role of photochemical and meteorological processes

Previous measurements of peroxyacetyl nitrate(PAN) in Asian megacities were scarce and mainly conducted for relative short periods in summer. Here, we present and analyze the measurements of PAN, O3, NOx, etc., made at an urban site(CMA) in Beijing from 25 January to 22 March 2010. The hourly concentration of PAN averaged 0.70 × 10 9mol/mol(0.23 × 10 9–3.51 × 10 9mol/mol) and was well correlated with that of NO2but not O3, indicating that the variations of the winter concentrations of PAN and O3in urban Beijing are decoupled with each other. Wind conditions and transport of air masses exert very significant impacts on O3, PAN, and other species. Air masses arriving at the site originated either from the boundary layer over the highly polluted N-S-W sector or from the free troposphere over the W-N sector. The descending free-tropospheric air was rich in O3, with an average PAN/O3ratio smaller than 0.031, while the boundary layer air over the polluted sector contained higher levels of PAN and primary pollutants, with an average PAN/O3ratio of 0.11. These facts related with transport conditions can well explain the observed PAN-O3decoupling. Photochemical production is important to PAN in the winter over Beijing. The concentration of the peroxyacetyl(PA) radical was estimated to be in the range of 0.0014 × 10 12–0.0042 × 10 12 mol/mol. The contributions of the formation reaction and thermal decomposition to PAN's variation were calculated and found to be significant even in the colder period in air over Beijing, with the production exceeding the decomposition.     

河南省北部区域霾污染过程中城市和农村点位PM2.5组分差异

近年来,我国京津冀及其周边地区暴发了多次霾污染过程,受观测仪器等因素的限制,尚未有对河南省北部城市和农村霾污染的对比研究.利用一系列在线高时间分辨率的观测仪器在河南省2个城市点位和3个农村点位对一次区域重污染过程(2018年1月12～25日)进行综合观测.结果表明SO₄^2-、 NO^-₃和NH⁺₄(SNA)是此次区域污染过程中5个点位PM_2.5中占比最高的组分,位于53%～63%之间,以NO^-₃为主24%～32%,其次为SO₄^2-(13%～17%).相较于城市点位,农村点位PM_2.5中有机物的占比更高,尤其是夜间.随着污染的加重,SNA的占比上升,重污染时段可达67%.此外,当区域受南部气团的传输影响时,5个点位PM_2.5中NO^-₃的占比增大;受北和东北部气团的传...     

Ambient concentrations,scavenging ratios,and source regions of acid related compounds and trace metals during winter in northern michigan

Daily measurements the atmospheric cocnentrations of HNO₃, NO₃^-, NO₂, SO₂, SO₄²⁻, NH₄⁺, and several trace metals were made at the University of Michigan Biological Station over a 124-day period during the 1984–1985 winter. The composition of the daily precipitation was also determined. The relative contributions of scavenged NO₃⁻ and HNO₃ to the precipitation was estimated by assuming that the NO₃⁻ scavenging ratio was the same as that of trace metals with a similar particle size. Similarly, the SO₄²⁻ and SO₂ contributions were based on the scavenging ratios of NH₄⁺ and trace metals. On this basis, it was determined that the event median NO₃⁻ and HNO₃ scavenging ratios were 500 and 3500, respectively. HNO₃ scavenging accounted for 83% of the total scavenged NO₃⁻. Scavenging of SO₄²⁻ accounted for all the snow SO₄²⁻ in 67% of the events. In the remaining events, some SO₂ was scavenged, with a median scavenging ratio of 219. Overall, 67% of the snowfall acidity appeared to be due to HNO₃ scavenging. Backward air-mass trajectories that were calculated for each event were used to determine the general source regions of the acidic species. Snow associated with air masses from the south and west accounted for 81 and 75% of the deposited NO₃⁻ and SO₄²⁻, respectively.     

利用多元线性回归方法评估气象条件和控制措施对APEC期间北京空气质量的影响

气象条件对大气污染物的扩散和传输有重要影响,准确分离和定量气象因素对空气质量的影响是评估大气污染控制政策有效性的前提.本研究利用APEC会议期间及前后(2014-10-15～2014-11-30)北京城区朝阳观测站点SO_2、NO、NO_2、NO_x、CO、PM_(2.5)、PM_1和PM_(10)以及气象因素的观测数据,采用多元线性回归分析方法,定量评估了气象条件和空气污染控制措施对APEC期间北京空气质量的影响.在假定排放条件不变的情况下,基于气象因素参数建立的预测污染物浓度的多元线性回归模型模拟效果较为理想,决定系数R~2在0. 494～0. 783之间.控制措施使得APEC控制期SO_2、NO、NO_2、NO_x、CO、PM_(2.5)、PM_1和PM_(10)浓度分别降低48. 3%、53. 5%、18. 7%、40. 6%、3. 6%、34. 8%、28. 8%和40. 6%,气象因素使得APEC控制期SO_2、NO、NO_2、NO_x、CO、PM_(2.5)、PM_1和PM_(10)浓度分别降低1. 7%、-2. 8%、18. 7%、4. 5%、18. 6%、27. 5%、30. 6%和35. 6%.气象因素和控制措施共同作用使得APEC控制期北京空气质量得到了明显改善.控制措施对SO_2和氮氧化物浓度的下降起主导作用,气象因素对CO浓度的下降起主导作用,气象因素和控制措施对颗粒物浓度降低的贡献相当.本研究还利用相对权重方法研究了气象因素对污染物浓度影响的贡献,结果表明影响不同污染物浓度的决定性气象因素不同.     

利用SPAMS研究石家庄市冬季连续灰霾天气的污染特征及成因

2014年11月18~26日石家庄市发生了连续的灰霾天气.利用位于石家庄市大气自动监测站(20 m)的单颗粒气溶胶质谱仪(SPAMS)分析了细颗粒物的化学组成,根据石家庄市大气污染物排放源谱库对主要成分进行了来源解析,并结合颗粒物质量浓度和气象条件研究了该地区冬季灰霾天气成因.结果表明,石家庄市大气细颗粒物来源分为7类,各源示踪离子:燃煤源为Al,工业源为OC、Fe、Pb,机动车尾气源为EC,扬尘源为Al、Ca、Si,生物质燃烧源为K和左旋葡聚糖,纯二次无机源为SO-4、NO-2和NO-3,餐饮源为HOC.灰霾期间大气中主要含有OC、HOC、EC、HEC、ECOC、富钾颗粒、矿物质和重金属等8类颗粒,其中OC和ECOC颗粒最多,分别占到总数的50%和20%以上,OC颗粒主要来自燃煤和工业工艺,ECOC颗粒主要来自燃煤和机动车尾气排放.灰霾发生时含有NH+4、SO-4、NO-2和NO-3等二次离子的颗粒物占比升高,其中含NH+4颗粒增幅最大;EC、OC与NO-3、SO-4、NH+4在灰霾天气下的混合程度均比干净天气高,其中与NH+4的混合程度加剧最为明显.冬季采暖期煤炭的大量燃烧、医化行业工艺过程及机动车尾气等污染源排放的一次气态污染物(SO2、NOx、NH3、VOCs)和一次颗粒物在静稳天气中难以扩散而迅速累积,气态污染物发生二次转化形成硝酸铵、硫酸铵,而颗粒物之间通过碰撞形成二次颗粒物并发生不同程度的混合,从而导致大气能见度下降,以上是石家庄市冬季灰霾形成的主要原因.     

Transverse approach between real world concentrations of SO2, NO2, BTEX, aldehyde emissions and corrosion in the Grand Mare tunnel

With regard to automotive traffic, a tunnel-type semi enclosed atmosphere is characterized by a higher concentration of gaseous pollutants than on urban traffic roads and highlights the gaseous effluent species having an impact on material degradation. Therefore, a transverse approach between air quality and its consequences upon the longevity of materials is necessary, implying better knowledge of tunnel atmosphere and a better understanding of material degradation inside a tunnel for operating administration. Gaseous pollutant measurements carried out in a road tunnel in Rouen (Normandy) give the real world traffic concentrations of experimental exposure conditions. The sampling campaigns, achieved in summer and winter include SO₂, NO₂, BTEX and aldehyde analyses. Effluent profiles in the upward and downward tubes have been established. The current work shows that SO₂, NO₂, formaldehyde, acetaldehyde, propanal and butanal must be considered in the degradation process of materials in a stuffy environment. As regards NO₂, its concentration depends on the modification of the automotive fleet. The total aldehyde concentrations indicate no particular trend between the two bores. Formaldehyde, acetaldehyde, propanal, butanal and acrolein species are the most abundant species emitted by vehicles and represent 90% to 95% of the total aldehyde emissions.