Carcinogenic potential, levels and sources of polycyclic aromatic hydrocarbon mixtures in indoor and outdoor environments and their implications for air quality standards

Both the World Health Organization and the UK Expert Panel on Air Quality Standards (EPAQS) have considered benzo(a)pyrene (BaP) as a marker of the carcinogenic potency of the polycyclic aromatic hydrocarbons (PAH) mixture, when recommending their respective guidelines for PAHs in outdoor air. The aim of this research is to compare the concentrations and relative abundance of individual PAH and their contribution to the overall carcinogenic potential of the PAH mixture in indoor and outdoor environments to assess the suitability of the UK air quality standard derived for outdoor air for use as a guideline for indoor environments. Samples were collected onto filters using active sampling in different indoor and outdoor microenvironments. The ratio of individual compounds to BaP, the BaP equivalent concentrations and the percentage contribution of each individual compound to the total carcinogenic potential of the PAH mixture were calculated. Mean concentrations were generally lower indoors (BaP=0.10 ng/m(3)) than outdoors (BaP=0.19 ng/m(3)), with the exception of indoor environments with wood burners (BaP=2.4 ng/m(3)) or ETS (BaP=0.6 ng/m(3)). The ratio of individual PAHs to BaP showed no significant differences between indoors (e.g. DahA/BaP=0.27) and outdoors (DahA/BaP=0.31). The relative contribution of BaP to the PAH overall carcinogenic potency is similar indoors (49%), outdoors (54%) and in the smelter environment (48%) used by EPAQS to derive the UK Air Quality Standard for ambient air. These results suggest the suitability of BaP as a marker for the carcinogenic potential of the PAH mixture irrespective of the environment. Despite small differences in PAH mixture composition indoors and outdoors, the level of protection afforded by the present EPAQS standard is likely to be similar whether it is applied to indoor or outdoor air.     

Characteristics of the PAH emissions from the incineration of livestock wastes with/without APCD

This study was conducted on two batch-type livestock waste incinerators, including the one with an air-pollution control device (APCD)-one wet scrubber (WSB) and the other without APCD for the disposal of livestock wastes. The concentration and composition of 21 individual polycyclic aromatic hydrocarbons (PAHs) in the stack flue gas (gas and particle phases), bottom ash, and effluent of WSB were determined. Stack flue gas samples were collected by a PAH stack-sampling system. Twenty-one individual PAHs were analyzed by a gas chromatography/mass spectrometer (GC/MS). Due to the low combustion temperature, a remarkable and significant increase in the total-PAH concentration of emission from the stack with APCD was observed when compared with the case without APCD. Measured total-PAH emission factors were 285 and 2.86 mg/kg waste for the incineration with and without APCD, respectively, while BaP (the most carcinogenic PAH) emission factors were 0.79 and 0.12 mg/kg waste for the incineration with and without APCD. The total-PAH output/input mass ratios averaged 0.011 and 0.004 with and without APCD, respectively. The result reveals that the PAH content in the auxiliary fuel during the incinerating process could affect the emission of PAH.     

Composition, sources, and potential toxicological significance of PAHs in the surface sediments of the Meiliang Bay, Taihu Lake, China

Twenty-five surface sediment samples were collected from Meiliang Bay, Taihu Lake, China, in 2003. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), identified as priority pollutants by the USEPA, were determined by gas chromatography equipped with a mass spectrometry detector (GC-MS). Total concentrations of the PAHs ranged from 1207 to 4754 ng/g dry weight. Sediment samples with the highest PAH concentrations were from the northern site of the bay, which is in proximity to the incoming PAH source; the PAH levels in the southern part were relatively low. The observed PAH levels were higher than those in river sediments in China but were lower than those found in sediments of urban areas and harbors. According to the observed molecular indices, PAHs originated largely from the high-temperature pyrolytic process, whereas the petrogenic process was more commonly responsible for PAH contamination in harbors. A good correlation existed between the benzo[a]pyrene level and the total PAH concentration (r=0.97), making benzo[a]pyrene a potential molecular marker for PAH pollution. According to the numerical effect-based sediment quality guideline (SQGs) of the United States, the levels of PAHs at most studied sites in Meiliang Bay, except some sites in the northern part of the bay, should not exert adverse biological effects. In the northern part of the bay, the PAH levels at sites 21 and 22 exceed the effects range low (ERL) and could thus cause acute biological impairments, in comparison with the sediment quality guidelines. The total PAH levels were expressed as the B[a]P toxicity equivalents (TEQs(carc)) and compared to the contaminated sediments from Guba Pechenga, Barents Sea, Russia.     

龙岩市省控断面水体中多环芳烃的污染特征、风险评价

对九龙江流域龙岩市省控断面2011年秋季、2012年冬季以及2012年春季河水中多环芳烃(PAHs)进行了分析。结果表明：该控断面河水中PAHs总量浓度变化为99~1788 ng/L，其组成特征是以3环(567%)、5环(246%)和4环(151%)为主，表明3环、4环及5环PAHs是九龙江流域龙岩市省控断面水中PAHs的最主要成分。地表水健康风险评价结果显示，红坊赤坑、雁石桥、捷步桥、顶坊4个采样点苯并\[a\]芘(BaP)毒性当量值(EBaP)均超出我国环境保护部(CEPA)制定的EBaP=2.8 ng/L的国家标准     

2015年长三角地区城市PM2.5时空格局及影响因素分析

PM_2.5浓度值增加对大气能见度、人体健康和气候变化有着重要影响。采用2015年长三角地区监测数据，运用探索性空间数据分析法和相关系数法，分析长三角地区城市PM_2.5污染的时空格局和影响因素，结果表明：（1）2015年长三角地区城市PM_2.5年均浓度值为54.54 μg/m³，季节变化总体呈现春冬高夏秋低的季节性周期变化规律，1月和12月为一年中PM_2.5污染最严重的月份，污染范围最广，5~9月是PM_2.5浓度值优良时段，日均值春季和冬季的波动周期较短而剧烈，夏季和秋季波动周期相对较长而平缓。（2）2015年长三角地区城市PM_2.5年均浓度值整体上从江苏到浙江呈减少趋势，具有北高南低，局部突出的特征。（3）长三角地区城市PM_2.5浓度空间上存在集聚现象，低值集聚主要分布在浙江沿海地区，高值集聚主要分布在苏南地区。（4）燃烧排放的烟尘和前体物的二次转化对长三角地区PM_2.5浓度有显著影响。风速和降水量是影响PM_2.5浓度的两个重要气象因素。     

长江中游城市群PM2.5时空特征及影响因素研究

近年来，伴随着工业化和城市化进程的加快，长江中游城市群灰霾天气持续增多，空气污染问题日益突出。基于2015年1月至2016年2月长江中游城市群189个空气质量监测站点的PM2.5逐时监测数据，采用普通克里金插值、探索性空间数据分析法和相关系数法，从年、季、月尺度上分析了PM2.5的空间分布格局及其影响因素。结果表明：（1）在年尺度上，长江中游城市群PM2.5浓度空间分布总体呈现出明显的北部高南部低，局部地区略有突出的特征，该区PM2.5浓度年均值为55.28 μg/m3，其中湖北省PM2.5的年均值为三省市最高，为68.17 μg/m3；其次为湖南省，年均值为53.66 μg/m3；江西省PM2.5的年均值较小，为44.01 μg/m3。（2）在季节尺度上，长江中游城市群PM2.5浓度表现出冬春季高，夏秋季低的现势性，这与区域内夏季高温多雨、冬季低温少雨的气候条件密切相关。（3）长江中游城市群PM2.5月浓度变化大致呈U形分布，1月份PM2.5浓度最高， 1~6月份，PM2.5浓度呈逐步下降趋势， 6~8月份，区域PM2.5浓度处于“U”字的谷底。（4）NO2、CO是影响PM2.5浓度的两项主控大气污染物，而降水量和相对湿度则是影响PM2.5浓度的两个重要气象因素。 关键词： PM2.5浓度；时空特征；气象因素；长江中游城市群     

Assessing inhalatory and dermal exposures and their resultant health-risks for workers exposed to polycyclic aromatic hydrocarbons (PAHs) contained in oil mists in a fastener manufacturing industry

This study first assessed workers' inhalatory and dermal exposures to polycyclic aromatic hydrocarbons (PAHs) contained in oil mists. Then, their resultant lung cancer and skin cancer risks were estimated. Finally, control strategies were initiated from the health-risk management aspect. All threading workers in a fastener manufacturing plant were included. 16 inhalatory and 88 dermal PAH exposure samples were collected. Results show that the inhalatory gas phase total PAH exposure level (8.60x10(4) ng/m(3)) was much higher than that of particle phase (2.30x10(3) ng/m(3)). Workers' mean inhalatory exposure level (8.83x10(4) ng/m(3)) was lower, but its corresponding 1-sided upper 95% confidence level (UCL(1,95%)=1.02x10(5) ng/m(3)) was higher than the time-weighted average permissible exposure level (PEL-TWA) regulated in Taiwan for PAHs (1.00x10(5) ng/m(3)). The mean whole body total PAHs dermal exposure levels was 5.44x10(6) ng/day and the top five exposed surface areas were lower arm, hand, upper arm, neck, and head/front. The estimated lifetime skin cancer risk (9.72x10(-3)) was lower than that of lung cancer risk (1.64x10(-2)), but both were higher than the significant risk level (10(-3)) defined by the US Supreme Court in 1980. The installation of a local exhaust ventilation system at the threading machine should be considered as the first priority measurement because both lung and skin cancer risks can be reduced simultaneously. If the personal protection equipment would be adopted in the future, both respiratory protection equipment and protective clothing should be used simultaneously.     

河口滨岸悬浮颗粒物中多环芳烃分布与风险评价

通过收集长江口滨岸13个典型采样点上覆水中的悬浮颗粒物,分析了悬浮颗粒中多环芳烃(PAHs)的含量水平,探讨了PAHs的来源,并进行了生态风险评价。研究结果显示,EPA14种优控PAHs的总量在600~12 308 ng/g 之间,平均值为5 373 ng/g,其组成主要以3环和4环PAH为主。受附近陆源输入的影响,顾路采样点的PAHs含量最高,此外,临近城市排污、滨岸工业开发区及河道排污口的采样点PAHs含量也较高,如石洞口、金山、白茆、浏河口等。结合PAHs不同环数的相对丰度与同分异构体荧蒽/芘、芘/苯并［a］蒽比值,初步推断出人类油污染及矿物燃料的不完全燃烧是悬浮颗粒物中PAHs的主要来源。此外,参照有关环境质量标准,发现悬浮颗粒物中萘、菲、芴、蒽/苯并［b］荧蒽和苯并［k］荧蒽等化合物已经产生不同程度的生物影响效应。     

A comparison of concentrations of polycyclic aromatic compounds detected in dust samples from various regions of the world

Settled house dust can be a source of human exposure to toxic polycyclic aromatic hydrocarbons (PAHs) through non-dietary ingestion and dermal contact. Information regarding the concentrations of various contaminants in house dust would be useful in estimating the risk associated with exposure to these compounds. This study reports on the surface loading, variability and distribution of PAHs in settled house dust collected from homes in three locations: Sumgayit, Azerbaijan; Shanxi Province, China; and southern Texas, United States. The highest PAH floor surface loadings were observed in China, followed by Azerbaijan and Texas. Median concentrations of high molecular weight (four ring and larger) PAHs ranged from a low of 0.11 microg/m(2) in Texas, to 2.9 microg/m(2) in Azerbaijan and 162 microg/m(2) in China. These trends in total surface loading and relative carcinogenicity indicate that the risk of health effects from exposure to PAHs in house dust is highest in the Chinese population and lowest in the Texas population. As anticipated, variability among dust samples from different houses within the same region was high, with coefficients of variation greater than 100%. Alkylated PAHs comprised 30-50% of the total mass of PAHs. Based on a comparison of the composition of specific components, PAHs in China and Azerbaijan were determined to be derived mainly from combustion sources rather than from unburned fossil fuels such as petroleum. These results, coupled with ongoing investigation of appropriate PAH exposure biomarkers in humans, will guide future efforts to identify ways to reduce exposures in the study areas.     

Polycyclic aromatic hydrocarbon contamination in coastal sediments of the Izmit Bay (Marmara Sea): case studies before and after the Izmit Earthquake

Izmit Bay and its coastal environment was strongly affected by the August 17th, 1999 Izmit Earthquake. The changes in the Bay ecosystem and its chemical oceanography have been studied in detail previously [Okay, O.S., Tolun, L, Telli-Karako?, F., Tüfek?i, V., Tüfek?i, H. And Morko?, E. 2001. Yzmit Bay ecosystem after Marmara earthquake and subsequent fire: The long-term data. Marine Pollution Bulletin 42, 361-369; Balkys, N. 2003. The effect of Marmara (Izmit ) Earthquake on the chemical oceanography of Izmit Bay, Turkey. Marine Pollution Bulletin 46, 865-878.]. In this study surface sediments collected from the Izmit Bay before and after the earthquake have been analysed for total and individual (14 compounds) polycyclic aromatic hydrocarbons (PAH). Analyses have been performed by high performance liquid chromatography with fluorescence detection (HPLC/FD). Before the earthquake, total PAH concentrations in the Bay sediments ranged from 120 to 8900 ng/g while after the earthquake PAH concentrations varied between 240 and 11,400 ng/g. Molecular indices based on isomeric PAH ratios used to differentiate the pollution sources, clearly indicate the differences in molecular distribution of PAHs before and after the earthquake. Sediment data obtained before the earthquake shows that most of the contamination originated from high temperature pyrolytic inputs while after the earthquake it originated from petrogenic sources. This difference emphasises the environmental impact of uncontrolled discharges from petroleum industries after the earthquake. The LMW/HMW ratio (sum of the low molecular weight PAHs / the sum of higher molecular weight PAHs) predominance also changed after the earthquake as a result of the strong water movements. According to the characteristics of aromatic rings distributed in the bay sediments, the soluble parts of the total PAH were probably transferred to the water column after the earthquake as a result of resuspension process. The TEL/PEL (Threshold Effect Level / Probable Effect Level) analysis suggests that the Izmit Bay sediments were likely contaminated by acutely toxic PAH compounds.     

乌江中上游新建水库水体甲基汞的时空分布

为了弄清新修建的水库是否造成水体甲基汞浓度升高，以贵州省乌江流域2座新建水库洪家渡水库和索风营水库为研究对象，采用蒸馏 乙基化结合（GC CVAFS）法测定了不同季节水库水体中甲基汞的浓度，最低检出限为 0.009 ng/L。探讨了水质参数对甲基汞分布的影响以及水库水体甲基汞的分布特征。结果显示:洪家渡水库总甲基汞浓度夏季平均值为 0.11 ng/L，秋季平均值为 0.08 ng/L，冬季平均值为 0.10 ng/L；索风营水库总甲基汞浓度夏季平均值为 0.11 ng/L，秋季平均值为 0.07 ng/L，冬季平均值为 0.09 ng/L。数据表明2座水库水体甲基汞含量均较低，低于目前我国环境质量标准规定的一类地表水汞含量标准限值，与世界上其他未受污染的水体基本相当。水库水体甲基汞浓度随水体深度的增加没有明显的变化规律，且夏季略高于冬季、秋季，这与夏季降雨量和温度有关，在入库处与大坝前没有明显的变化趋势。这与水库中被淹没土壤有机质含量偏低且流域内基岩为碳酸盐有关，还与其他环境因素有关(如pH值较高，DOC含量偏低等)。通过研究发现目前库区环境汞的甲基化率低，但随着水库生态系统的不断演化，内源和外源营养物的输入及水体在温度分层其间自身甲基汞的形成，导致水体甲基汞含量的逐渐增加，但仍需进一步的研究证实。     

Polycyclic aromatic hydrocarbons in ambient air particles in the city of Las Palmas de Gran Canaria

Concentration levels, seasonal variation and winter/summer ratios of 11 polycyclic aromatic hydrocarbons (PAHs) in the TSP of Las Palmas de Gran Canaria city were determined. The study area is under the influence of heavy traffic (80000 vehicles/day). Pyr/BaA, Pyr/Flt, B(ghi)P/I(cd)P and B(b+k)F/B(ghi)P ratios were calculated; the values of these two last suggest a strong influence of diesel fuel burning. Levels of TSP and TSP-bound PAHs were also established. The hazard potential of PAHs in terms of carcinogenicity of BaP is acceptable. Potential risk on the basis of TEFs is also studied.     

江苏天目湖表层沉积物中多环芳烃污染特征与来源

区别于长江三角洲地区众多的大型天然浅水湖泊，江苏天目湖是一个较深的水库型湖泊，也是重要的城乡生活及工农业水源地之一。为了解天目湖表层沉积物中多环芳烃（PAHs）污染状况， 2006年在天目湖全湖采集7个点位的表层沉积物样品，利用GC/MS分析了16种优控PAHs。结果表明：天目湖表层沉积物中16种优控PAHs总量介于28750~71393 ng/g（干重），平均值为45852 ng/g；在空间分布上，北部受污染程度高于南部，主要是北部旅游业快速发展导致污染物排放的影响；沉积物中总有机碳含量与PAHs总量呈显著相关；利用特征化合物指数对PAHs的来源进行判别，指示天目湖表层沉积物中PAHs的主要来源是木材、煤的不完全燃烧。与不同地区水体沉积物PAHs含量对比表明，天目湖PAHs污染处于一个低至中等程度。基于沉积物中多环芳烃的环境质量标准，仅有1个样点芴浓度超过风险效应低值，但远小于毒性风险效应中值，因此沉积物中多环芳烃的生态风险较小。然而天目湖表层沉积物中的PAHs的污染程度已超过南水北调东线所经过的南四湖，而且天目湖湖水较深，湖水交换周期比较长，其PAHs污染应引起重视，需制定切实措施保护江苏“最后一泓净水”。     

Seasonal assessment of environmental tobacco smoke and respirable suspended particle exposures for nonsmokers in Bremen using personal monitoring

The study was designed to determine seasonal differences in personal exposures to respirable suspended particles (RSP) and environmental tobacco smoke (ETS) for nonsmokers in Bremen, Germany. The subjects were office workers, either living and working in smoking locations or living and working in nonsmoking locations. One hundred and twenty four randomly selected nonsmoking subjects collected air samples close to their breathing zone by wearing personal monitors for 24 h or, in some cases, for 7-day periods during the winter of 1999. The investigation was repeated in the summer with 126 subjects, comprised of as many of the studied winter population (89 subjects) as possible. Saliva cotinine analyses were undertaken to verify the nonsmoking status of the subjects. Subjects wore one personal monitor while at work and one while away from the workplace on weekdays, and a third monitor at the weekend. Collected air samples were analysed for RSP, nicotine, 3-ethenylpyridine (3-EP) and ETS particles. The latter were estimated using ultraviolet absorbance (UVPM), fluorescence (FPM) and solanesol (SolPM) measurements. ETS exposure was consistently higher in the winter than in the summer, this pattern being particularly evident for subjects both living and working with smokers. The highest median 24-h time weighted average (TWA) concentrations of ETS particles (SolPM, 25 microg m(-3)) and nicotine (1.3 microg m(-3)) were recorded for subjects performing weekday monitoring during the winter. These were significantly higher than equivalent levels of ETS particles (SolPM, 2.4 microg m(-3)) and nicotine (0.26 microg m(-3)) determined during the summer. There were no appreciable differences between winter and summer percent workplace contributions to median TWA ETS particle and nicotine weekday concentrations, the workplace in Bremen, in general, contributing between 35% and 61% of reported median concentrations. Workers, on average, spent one-third of their time at work during a weekday, indicating that concentrations were either comparable or higher in the workplace than in the home and other locations outside the workplace. Median 24-h weekend ETS particle and nicotine concentrations for smoking locations were not significantly different from equivalent weekday levels during the winter, but were significantly lower during the summer. Based upon median 24-h TWA SolPM and nicotine concentrations for the winter, extrapolated to 1 year's ETS exposure, those subjects both living and working in smoking locations (the most highly exposed group) would potentially inhale 13 cigarette equivalents/year (CEs/y). However, based on a similar extrapolation of summer measurements, the same group of subjects would potentially inhale between 1.3 and 1.9 CEs/y. The most highly exposed subjects in this study, based upon 90th percentile concentrations for those both living and working in smoking locations during the winter, would potentially inhale up to 67 CEs/y in the winter and up to 22 CEs/y in the summer. This clearly demonstrates that seasonal effects should be taken into account in the design and interpretation of ETS exposure studies. Air sampling over a 7-day period was shown to be technically feasible, and subsequent RSP, ETS particle and nicotine levels determined by 7-day monitoring were not found to be significantly different from equivalent levels determined by 24-h monitoring. However, the longer sampling period resulted in the collection of an increased quantity of analytes, which improved the limits of quantitation (LOQ) and allowed a more accurate determination of low level ETS exposure. This was reflected by a reduced percentage of data falling below the LOQ for 7-day monitoring compared with 24-h monitoring. The use of a liquid chromatographic method with tandem mass spectrometric detection for saliva cotinine measurement afforded a greatly improved LOQ and greater accuracy at low concentrations compared with the radioimmunoassay (RIA) method used in previous studies by these authors. In this study, 17 subjects out of 180 tested (9.4%) were found to have saliva cotinine levels exceeding the selected threshold of 25 ng ml(-1) used to discriminate between smokers and nonsmokers.     

Long period study of outdoor radon concentration in Milan and correlation between its temporal variations and dispersion properties of atmosphere

The results of a survey of outdoor radon concentrations in Milan are reported. Measurements were performed hourly over a continuous four year period from January 1997 to December 2000. Radon concentration was obtained by two means: both direct measurement of radon; and measurement of its decay products. The average daily pattern of radon concentration featured a minimum in the late afternoon and a maximum in the early hours of the morning. A seasonal pattern with higher concentrations in winter than in summer (from around 15 Bq m(-3) in winter to around 5 Bq m(-3) in summer) was also observed. Similar average annual values of around 10 Bq m(-3) were obtained. The annual effective outdoor radon dose was found to be 0.12 mSv. The variation from minimum in the afternoon to maximum the following morning was found to be a good indicator of the height of the nocturnal mixing layer. The variation between maximum and minimum levels on the same day is an index of the maximum height of the mixing layer. Furthermore, our long term measurements of radon have permitted us to examine the dispersion characteristics of the atmosphere over Milan, and to establish the frequency of conditions unfavourable to the dispersion of atmospheric pollutants.     

The study of Central Taiwan particles concentration variations during earthquake period

Ambient particle concentration was taken on the traffic sampling site over the Chung-Chi Road over the bridge (CCROB) in front of Hungkuang Institute of Technology (HKIT). The sampling time was from August 1999 to December 1999. During the sampling period, Taiwan's biggest earthquake in more than a century registered 7.3 on the Richter scale (Taiwan Chi-Chi Earthquake). Besides, there are more than 20,000 aftershocks following the Taiwan Chi-Chi Earthquake within 3 months. Thus, the mass concentration of particles with aerodynamic diameters smaller than 2.5 microm (PM2.5) and PM2.5-10 was also collected then compared with the total mass concentration of suspended particles (TSP) in this study. The average TSP, PM2.5-10, and PM2.5 concentrations are 106, 24.6, and 58.0 microg/m3, respectively, after the Taiwan Chi-Chi Earthquake. The average TSP concentrations before and after Taiwan Chi-Chi Earthquake were 69.6 and 127 microg/ m3, respectively. In addition, statistical analysis of the PM10 data from this study and EPA in 1999 yielded a Tstatistic of 0.147, which is smaller than t(0.975,18) = 2.101. It is indicated that there was no significant difference. So, the PM10 concentrations measured after Taiwan Chi-Chi Earthquake in this study were also greater than those data previously obtained from Taiwan EPA in the same region of this area. The relationships between TSP, PM10, PM2.5-10, and PM2.5 particle concentrations and wind speed (R2) are .77, .59, .58, .58, respectively. And the ratios of PM2.5/PM25-10, PM2.5/PM10, and PM10/TSP are 221%, 67.2%, 58.0%, respectively. The average ratios of PM2.5/PM2.5-10 and PM2.5/PM10 increase by about 120% and 17%. It indicated that the fine-particles concentration increases compared to the coarse-particles concentration after 921 Taiwan Chi-Chi Earthquake. And the proposed reasons are that local motor vehicle emissions combined the fine particles transported from the Chi-Chi epicenter. More importantly, the wind direction was mainly blown from southeastern part. These two main factors enhance the fine-particles concentration in this area.     

A survey of radon level in underground buildings in China

From 2003-2004, using solid state nuclear detectors, a survey of the air radon level in 234 underground buildings in 23 cities of China was carried out during spring as well as summer and winter. The annual radon concentrations in these underground buildings range from 14.9 to 2482 Bq m(-3), with an overall mean value of 247 Bqm(-3). When radon concentrations are averaged according to cities, Fuzhou and Baotou have the relatively higher radon levels, which are 714 and 705 Bqm(-3), respectively. Guangzhou and Shanghai have the relatively lower radon levels with 71.1 and 72.6 Bqm(-3). The annual effective dose by exposure to radon received by people working in these cities is concluded to be 1.6 mSv. The geological formation, coating level, decorating materials and ventilation situation all affect the radon concentration in underground buildings. The radon level in underground buildings has the lowest value in winter and the highest value in summer.     

Variations in the concentration of radon in parts of the Ogof Ffynnon Ddu system, Penwyllt, South Wales and estimates of doses to recreational cavers.

A new winter and summer investigation of radon concentrations in parts of the Ogof Ffynnon Ddu system at Penwyllt, South Wales, has been carried out using 100 environmental National Radiological Protection Board track etch detectors. Fifty detectors were installed in the system in December 1998 and again in August 1999 for a period of a month. The data obtained confirm that the system has moderately high radon concentrations with a system mean of 2318 Bq m(-3) in winter and 2844 Bq m(-3) in summer. Traverse means have a summer high of 3094 Bq m(-3) for OFDI to Cwm Dwr and a winter low of 1946 Bq m(-3). The extremely high concentrations approaching 20,000 Bq m(-3), reported previously from the system (Hyland, 1995), have not been reproduced. The data show that the airflow directions at the entrances are not what might have been predicted. Air appears to be largely continuously emerging from the lowest entrance but, at the higher entrances, conversely to the predictions, in winter air enters and in summer appears to be coming out or is variable. Internally, there are sites that in winter have very low radon concentrations that can only be explained by the ingress of fresh air. These are not matched in the summer experiment, again indicating that ingress of fresh air to some parts of the system is very variable. The data illustrate the complexity of airflow within a multi-entrance system but behind these variations several mean concentrations can be obtained from which an approximation of the dose likely to be received can be calculated. Using the maximum mean concentration obtained, 3094 Bq m(-3), and using the latest dose conversion, a 10 h underground trip in the Ogof Ffynnon Ddu system yields a calculated dose of 0.12 mSv. Given that the recommended limit for a member of the public is 1 mSv, this dose would be reached after about 80 h of caving in the system.     

Differentiating the effects of fine and coarse particles on daily mortality in Shanghai, China

The findings on health effects of ambient fine particles (PM2.5) and coarse particles (PM10-2.5) remain inconsistent. In China, PM2.5 and PM10-2.5 are not the criteria air pollutants, and their monitoring data are scarce. There have been no epidemiological studies of health effects of PM2.5 and PM10-2.5 simultaneously in China. We conducted a time series study to examine the acute effects of PM2.5 and PM10-2.5 on daily mortality in Shanghai, China from Mar. 4, 2004 to Dec. 31, 2005. We used the generalized additive model (GAM) with penalized splines to analyze the mortality, air pollution and covariate data. The average concentrations of PM2.5 and PM10-2.5 were 56.4 microg/m3 and 52.3 microg/m3 in our study period, and PM2.5 constituted around 53.0% of the PM10 mass. Compared with the Global Air Quality Guidelines set by World Health Organization (10 microg/m3 for annual mean) and U.S. National Ambient Air Quality Standards (15 microg/m3 for annual mean), the PM2.5 level in Shanghai was much higher. We found that PM2.5 was associated with the death rates from all causes and from cardiorespiratory diseases in Shanghai. We did not find a significant effect of PM10-2.5 on mortality outcomes. A10 microg/m3 increase in the 2-day moving average (lag01) concentration of PM2.5 corresponded to 0.36% (95% CI 0.11%, 0.61%), 0.41% (95% CI 0.01%, 0.82%) and 0.95% (95% CI 0.16%, 1.73%) increase of total, cardiovascular and respiratory mortality. For PM10-2.5, the effects were attenuated and less precise. Our analyses provide the first statistically significant evidence in China that PM2.5 has an adverse effect on population health and strengthen the rationale for further limiting levels of PM2.5 in outdoor air in Shanghai.     

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived (222Rn) decay products 214Pb and 210Pb. The samples were taken by using a single-filter technique and gamma-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214Pb and 210Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214Pb and 210Pb within the whole year was found to be 1.4+/-0.27 Bq m(-3) and 1.2+/-0.15 mBq m(-3), respectively. Different 210Pb:214Pb activity ratios during the year varied between 1.78 x 10(-4) and 1.6 x 10(-3) with a mean value of 8.9 x 10(-4) +/- 7.6 x 10(-5). From the ratio between the activity concentrations of the radon decay products 214Pb and 210Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5+/-0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air.