Intraurban variations of PM10 air pollution in Christchurch, New Zealand: implications for epidemiological studies

Epidemiological studies relating air pollution to health effects often utilise one or few central monitoring sites for estimating wider population exposures to outdoor particulate air pollution. These studies often assume that highly correlated particulate concentrations between intraurban sites equate to a uniform concentration field. Several recent studies have questioned the universal validity of this assumption, noting that in some cities, the uniformity assumption may lead to exposure misclassification in health studies. Few studies have compared central fixed site concentrations to intraurban population background sites using actual monitored data in cities with higher levels of pollution. This research examines daily concentration variations in particulate matter less than 10 microm in diameter (PM10) at the neighbourhood scale over two winter months in Christchurch, New Zealand, a city with high winter pollution concentrations. Daily concentrations of PM10 data were collected for two winter months at ten background monitoring sites within 9.3 km of the central fixed monitoring site typically used for estimating exposure in epidemiological studies. Results indicate that while the correlation between PM10 concentrations measured at the central monitoring site and most background sites is strong (r>0.76), absolute daily concentration differences between the central monitoring site and population background sites were substantial (mean 90th percentile absolute difference=17.6 microg m-3). In Christchurch, a central monitoring site does not therefore appear to accurately depict wider area population exposures to PM10. Local intraurban variations in particulates should be well understood before applying central monitoring site concentrations as proxies for population exposure in epidemiological studies.     

Measurements of particulate matter within the framework of the European Monitoring and Evaluation Programme (EMEP) I. First results

Particulate matter (PM) monitoring presents a new challenge to the transboundary air pollution strategies in Europe. Evidence for the role of long-range transport of particulate matter and its significant association with a wide range of adverse health effects has urged for the inclusion of particulate matter within the European Monitoring and Evaluation Programme (EMEP) framework. Here we review available data on PM physico-chemical characteristics within the EMEP framework. In addition we identify future research needs for the characterisation of the background PM in Europe that include detailed harmonised measurements of mass, size and chemical composition (mass closure) of the ambient aerosol.     

Elevated concentrations of 1-hydroxypyrene in schoolchildren during winter in Christchurch, New Zealand

Particulate air pollution is significantly elevated during the winter in Christchurch, New Zealand, largely attributable to use of wood burners for domestic home heating, topography, and meteorological conditions. Polycyclic aromatic hydrocarbons (PAHs) are a key component of airborne particulate matter (PM) and urinary 1-hydroxypyrene (1-OHP) has previously been used to assess exposure of people to PAHs. We examined urinary 1-OHP in Christchurch male non-smoking schoolchildren (12-18 yr) on two occasions after high pollution events (48 and 72 microg PM(10)/m(3) 24-h average) and two occasions during periods of low pollution (19 and 12 microg PM(10)/m(3)). Concentrations of urinary 1-OHP were significantly elevated in the students during high pollution events (median (mean+/-SD) 0.043 (0.051+/-0.032) and 0.042 (0.060+/-0.092) micromol OHP/mol creatinine respectively) compared with low pollution periods (median (mean+/-SD) 0.019 (0.026+/-0.032) and 0.025 (0.028+/-0.018) micromol/mol creatinine respectively). The observed 1-OHP concentrations are at the lower end of those determined in children and non-occupationally exposed adults in international studies and suggest a generally low exposure to PAHs. The increased urinary 1-OHP concentrations following nights of elevated particulate concentrations in ambient air suggest increased exposure to ambient air pollution during winter time, and could potentially be used as a biomarker of exposure in this population.     

Improvement of predicted fine and total particulate matter (PM) composition by applying several different chemical scenarios: a winter 2005 case study

A new method using several different chemical scenarios is developed to predict chemical composition of fine (PM2.5) and total (PM10) aerosol. This method improves the accuracy of predicted PM concentrations. The Mesoscale Model version 5 (MM5) and a 3-dimensional Eulerian chemical model (CAMx4.2) are used to predict PM2.5 and PM10 concentrations using gridded input emissions (from the "Total" group) over a 48-72 h time period for Christchurch (New Zealand) for winter 2005. The aerosol concentrations are obtained for four different chemical compositions (chemical scenarios) of the input aerosol emissions. PM2.5 chemical compositions are based on previous Christchurch winter studies and from observations in other countries with similar winter pollution problems, and used in CAMx4.2 to model seven winter 2005 heavy pollution episodes. The error between observed and modelled PM2.5 concentrations is based on predictions of fine aerosol that are derived from linear regression with PM10. It is used to find the minimum difference between modelled and observed PM2.5 for an observation site located in the Christchurch residential area. Combination of the chemical scenarios with analysis of the minimum error is used to create a new complex chemical scenario. The new complex scenario is used to re-calculate all pollution episodes to obtain new values of PM with minimum error compared with observed aerosol concentrations. Mean Absolute Error of the calculated PM2.5 (for all pollution episodes) decreased from 21-24 microg m(-3) to 14-16 microg m(-3) compared with observations. The chemical composition of the modelled PM2.5 is also discussed.     

Effects of personal particulate matter on peak expiratory flow rate of asthmatic children

Many researches have shown that the particulate matter (PM) of air pollution could affect the pulmonary functions, especially for susceptible groups such as asthmatic children, where PM might decrease the lung function to different extents. To assess the effects of PM on health, most studies use data from ambient air monitoring sites to represent personal exposure levels. However, the data gathered from these fixed sites might introduce certain statistical uncertainties. The objectives of this study are to evaluate the effects of various size ranges of PM on peak expiratory flow rate (PEFR) of asthmatic children, and to compare the model performance of using different PM measurements (personal exposures versus fixed-site monitoring) in evaluation. Thirty asthmatic children, aged 6 to 12 years, who live near the fixed monitoring site in Sin-Chung City, Taipei County, Taiwan, were recruited for the study. Personal exposures to PM(1), PM(2.5), and PM(10) were measured continuously using a portable particle monitor (GRIMM Mode 1.108, Germany). In addition, an activity diary and questionnaires were used to investigate possible confounding factors in their home environments. The peak expiratory flow rate of each participant was monitored daily in the morning and in the evening for two weeks. Results showed several trends, although not necessarily statistically significant, between personal PM exposures and PEFR measurements in asthmatic children. In general, notable findings tend to implicate that not only fine particles (PM(2.5)) but also coarse particles (PM(2.5-10)) are likely to contribute to the exacerbation of asthmatic conditions. Stronger lagged effect and cumulative effect of PM on the decrements in morning PEFR were also found in the study. Finally, results of linear mixed-effect model analysis suggested that personal PM data was more suitable for the assessment of change in children's PEFR than ambient monitoring data.     

Exploratory investigation of the chemical characteristics and relative toxicity of ambient air particulates from two New Zealand cities

We examined the chemical composition and biological response associated with particulate emissions from the two largest cities in New Zealand, Auckland and Christchurch. The organic and water-soluble fractions were isolated from the particulate matter (PM). The organic fraction was examined for PAH content, direct mutagenicity, CYP1A1 induction, and cytotoxicity and TNF-α release in RAW264.7 macrophages. The water-soluble fraction was examined for metal content, and cytotoxicity and TNF-α release in RAW264.7 macrophages.Particulate, PAH and water-soluble metal concentrations were all higher in PM collected from Christchurch, being highest in May-July when woodburners for home heating are widely in use. In contrast, PM from Auckland showed the highest concentrations in March, but PAH and metal concentrations were highest in July. We found marked differences in the biological response elicited by ambient air PM: the organic extracts of Christchurch PM_2.5 and PM₁₀ showed higher mutagenicity and CYP1A1 induction compared with PM₁₀ from Auckland. In contrast, water-soluble extracts of Auckland PM were more cytotoxic and resulted in greater TNF-α release than those from Christchurch PM, although they had a lower metal content. The organic fraction of PM from both cities did not induce any cytokine release, and the organic extract from Auckland samples showed no cytotoxicity; smaller PM mass was available for testing for these samples. Biological responses typically occurred at lower doses of the organic extract, indicating that organic components may be more important in eliciting effects than water-soluble components.Preliminary apportionment of the biological responses to the dominant sources of PM in both cities-woodburners and vehicles-was undertaken. This indicated that for both cities, vehicles have a greater contribution to the direct mutagenic activity of ambient PM than woodsmoke, despite a lower contribution to ambient PM. In contrast, woodsmoke is estimated to have a greater contribution to CYP1A1 induction of ambient PM. The calculated activity forms only a small proportion of the activity observed in extracts of ambient PM from Christchurch, particularly for mutagenicity, and may indicate a significant influence of atmospheric transformation processes on biological response. Only data for mutagenicity and CYP1A1 activity could be used for apportionment as low and/or variable cytotoxicity or TNF-α release response were obtained for either the individual source or ambient PM at the doses tested. Further, in the case of the water-soluble extracts from Auckland, additional components are suggested to have a role in the observed activity.     

Evaluation of a year-long dispersion modelling of PM10 using the mesoscale model TAPM for Christchurch, New Zealand

This paper examines the utility of The Air Pollution Model (TAPM; version 2) in simulating meteorology and dispersion of PM(10) for 1999 over the coastal city of Christchurch, New Zealand. Christchurch usually experiences severe degradation in air quality during austral winter. The formation of a nocturnal inversion layer and the emissions of particulate matter (PM(10)) mainly from solid fuel home heating appliances lead to severe smog episodes on an average of 30 nights during winter. The complex local topography surrounding the city in combination with influences from the urban areas can produce complicated boundary layer winds during quiescent weather. Simulated PM(10) data are used for construction of annual exposure maps for the urban areas in order to assess the health impact of air pollutants due to chronic exposure (presented in an accompanying paper). Meteorology and PM(10) dispersion results are statistically compared with the only permanent air pollution monitoring station available in order to evaluate the model's performance. Statistical measures such as the Index of Agreement (IOA) between modelled and measured data indicate that the model performs well. IOA is greater than 0.6 for meteorological variables, and various calculated skill scores place confidence in the model's performance. However, TAPM has a tendency to overestimate surface wind speed over urban areas during stagnant nocturnal conditions, resulting in quick flushing of pollutants.     

Particulate matter and carbon monoxide multiple regression models using environmental characteristics in a high diesel-use area of Baguio City, Philippines

In Baguio City, Philippines, a mountainous city of 252,386 people where 61% of motor vehicles use diesel fuel, ambient particulate matter <2.5 microm (PM(2.5)) and <10 microm (PM(10)) in aerodynamic diameter and carbon monoxide (CO) were measured at 30 street-level locations for 15 min apiece during the early morning (4:50-6:30 am), morning rush hour (6:30-9:10 am) and afternoon rush hour (3:40-5:40 pm) in December 2004. Environmental observations (e.g. traffic-related variables, building/roadway designs, wind speed and direction, etc.) at each location were noted during each monitoring event. Multiple regression models were formulated to determine which pollution sources and environmental factors significantly affect ground-level PM(2.5), PM(10) and CO concentrations. The models showed statistically significant relationships between traffic and early morning particulate air pollution [(PM(2.5)p=0.021) and PM(10) (p=0.048)], traffic and morning rush hour CO (p=0.048), traffic and afternoon rush hour CO (p=0.034) and wind and early morning CO (p=0.044). The mean early morning, street-level PM(2.5) (110+/-8 microg/m3; mean+/-1 standard error) was not significantly different (p-value>0.05) from either rush hour PM(2.5) concentration (morning=98+/-7 microg/m3; afternoon=107+/-5 microg/m3) due to nocturnal inversions in spite of a 100% increase in automotive density during rush hours. Early morning street-level CO (3.0+/-1.7 ppm) differed from morning rush hour (4.1+/-2.3 ppm) (p=0.039) and afternoon rush hour (4.5+/-2.2 ppm) (p=0.007). Additionally, PM(2.5), PM(10), CO, nitrogen dioxide (NO2) and select volatile organic compounds were continuously measured at a downtown, third-story monitoring station along a busy roadway for 11 days. Twenty-four-hour average ambient concentrations were: PM(2.5)=72.9+/-21 microg/m3; CO=2.61+/-0.6 ppm; NO2=27.7+/-1.6 ppb; benzene=8.4+/-1.4 microg/m3; ethylbenzene=4.6+/-2.0 microg/m3; p-xylene=4.4+/-1.9 microg/m3; m-xylene=10.2+/-4.4 microg/m3; o-xylene=7.5+/-3.2 microg/m3. The multiple regression models suggest that traffic and wind in Baguio City, Philippines significantly affect street-level pollution concentrations. Ambient PM(2.5) levels measured are above USEPA daily (65 microg/m3) and Filipino/USEPA annual standards (15 microg/m3) with concentrations of a magnitude rarely seen in most countries except in areas where local topography plays a significant role in air pollution entrapment. The elevated pollution concentrations present and the diesel-rich nature of motor vehicle emissions are important pertaining to human exposure and health information and as such warrant public health concern.     

Particle size distribution and composition in a mechanically ventilated school building during air pollution episodes

Particle count-based size distribution and PM(2.5) mass were monitored inside and outside an elementary school in Salt Lake City (UT, USA) during the winter atmospheric inversion season. The site is influenced by urban traffic and the airshed is subject to periods of high PM(2.5) concentration that is mainly submicron ammonium and nitrate. The school building has mechanical ventilation with filtration and variable-volume makeup air. Comparison of the indoor and outdoor particle size distribution on the five cleanest and five most polluted school days during the study showed that the ambient submicron particulate matter (PM) penetrated the building, but indoor concentrations were about one-eighth of outdoor levels. The indoor:outdoor PM(2.5) mass ratio averaged 0.12 and particle number ratio for sizes smaller than 1 microm averaged 0.13. The indoor submicron particle count and indoor PM(2.5) mass increased slightly during pollution episodes but remained well below outdoor levels. When the building was occupied the indoor coarse particle count was much higher than ambient levels. These results contribute to understanding the relationship between ambient monitoring station data and the actual human exposure inside institutional buildings. The study confirms that staying inside a mechanically ventilated building reduces exposure to outdoor submicron particles. PRACTICAL IMPLICATIONS: This study supports the premise that remaining inside buildings during particulate matter (PM) pollution episodes reduces exposure to submicron PM. New data on a mechanically ventilated institutional building supplements similar studies made in residences.     

Burden of disease attributed to anthropogenic air pollution in the United Arab Emirates: Estimates based on observed air quality data

This study quantifies the national burden of disease attributed to particulate matter (PM) and ozone (O₃) in ambient air in the United Arab Emirates (UAE), a rapidly growing nation in which economic development and climatic conditions pose important challenges for air quality management. Estimates of population exposure to these air pollutants are based on observed air quality data from fixed-site monitoring stations. We divide the UAE into small grid cells and use spatial-statistical methods to estimate the ambient pollutant concentrations in each cell based on the observed data. Premature deaths attributed to PM and O₃ are computed for each grid cell and then aggregated across grid cells and over a year to estimate the total number of excess deaths attributable to ambient air pollution. Our best estimate is that approximately 545 (95% CI: 132-1224) excess deaths in the UAE in the year 2007 are attributable to PM in ambient air. These excess deaths represent approximately 7% (95% CI: 2-17%) of the total deaths that year. We attribute approximately 62 premature deaths (95% CI: 17-127) to ground-level O₃ for the year 2007. Uncertainty in the natural background level of PM, due to the frequent dust storms occurring in the region, has significant impacts on the attributed mortality estimates. Despite the uncertainties associated with the integrated assessment framework, we conclude that anthropogenic ambient air pollution, in particular PM, causes a considerable public health impact in the UAE in terms of premature deaths. We discuss important uncertainties and scientific hypotheses to be investigated in future work that might help reduce the uncertainties in the burden of disease estimates.     

大气可吸入颗粒物对IAQ的影响研究进展

回顾了可吸和颗粒物对人体健康的影响及其量化指标和测量方法，重点介绍了一些国家关于大气颗粒污染对室内空气品质影响的研究成果和进展，并对国内现状进行了分析。最后得出结论：大气可吸入颗粒物对室内空气品质有着重大影响，需要引起我国室内空气品质、环境科学和公共卫生学者的高度重视，并共同努力促进问题的解决。     

Pedestrians' perception of environmental stimuli through field surveys: focus on particulate pollution

The between perception of individual exposure to different environmental stimuli; microclimate, noise and especially particulate matter (PM) was examined. Microclimate, noise and PM were monitored during field surveys with 260 questionnaire-guided interviews at a road construction site and a traffic site on the UC San Diego campus. The overall comfort was determined primarily by the thermal environment. The air quality was considered to be poor by 42% of the interviewees at the construction site, which was burdened with higher PM counts and sound levels. Overall, higher PM concentrations were correlated with perception of poor air quality. Similarity between the overall air quality and how dusty it feels suggests that visual clues of PM, such as dust, affect the perception of air quality and pollution. The effect of medical or smoking history on the perceived air quality was also examined. People with a medical history of hay fever voted more frequently for poor air quality conditions than those without, whereas current smokers were the least sensitive to ambient air quality conditions. Through the exposure-response relationships between the various perception votes and PM, it was possible to predict perceived air cleanness using the PM count. Understanding the human assessment of environmental stimuli could inform the design and development of urban spaces, in relation to the allocation of uses and activities, along with air quality management schemes.     

2,3,7,8-TCDD equivalence and mutagenic activity associated with PM10 from three urban locations in New Zealand

Ambient particulate matter (PM(10)) in urban centres varies depending on emission sources, geography, demography, and meteorology. Hence physical (PM(10), wind speed, rainfall, temperature), chemical (polycyclic aromatic hydrocarbons, PAH), and toxicological (Ames Test, H4IIE EROD Assay) analyses were done on daily PM(10) (approximately 1640 m(3)/day) collected from three New Zealand urban sites where winter emissions were predominantly due to domestic home heating. Daily PM(10) levels ranged between 9.7 and 20.8 in summer and between 21.8 and 61.0 microg/m(3) in winter. Daily PAH concentrations were 0.5, 0.45, and 1.5 ng/m(3) in summer and 52.1, 128.9, and 5.8 ng/m(3) in winter at sites Christchurch, Alexandra and Dunedin, respectively. During winter, 74% of PM(10) extracts from all three sites showed significant mutagenicity in the Ames Test (TA 98, -S9), whereas approximately 25% of the daily PM(10) was mutagenic in summer. Benzo[a]pyrene and BaP carcinogenic equivalence concentrations during winter were strongly correlated to both mutagenicity and TCDD-like activity at two sites. Daily levels of TCDD toxicity equivalence concentrations ranged from 0.5 to 3.6 pg TCDD/m(3) air in summer and from 0.3 to 4009 pg TCDD/m(3) air in winter. Chemically and biologically derived TCDD toxicity equivalent concentrations were significantly correlated in all study locations indicating that PAH may represent most of the TCDD-like activity present in the PM(10).     

基于公共健康视角的城市公园颗粒物 时空分布及影响因素研究

城市公园是主要的室外公共空间,其大气颗粒物污染的时空分布与居民健康密切相关。在秋季晴朗微风天气,在郑州人民公园5类园林空间(露天广场、草坪、半室内空间、林下空间、滨水空间),监测不同空间中颗粒物(PM_1、PM_(2.5)、PM_(10))浓度和环境因子(风速、温度、湿度、天空可视因子、叶面积指数),探究城市公园中不同空间颗粒物浓度时空分布差异及与环境因子的关系。结果表明,草坪在8:00—14:00与其他空间PM_1、PM_(2.5)浓度有显著差异(P0.05);不同空间颗粒物浓度日均变化趋势相同,部分时段间存在显著差异(P 0.05),峰谷均在14:00—16:00,因而在颗粒物浓度较低的14:00—16:00更合适户外活动;相同空间3种颗粒物浓度均与空气温度显著负相关,与相对湿度显著正相关;空间内下垫面类型、人群的活动方式、周边植物群落结构等对颗粒物浓度均有影响。研究结果为公共健康视角下公园规划设计及居民对公园的使用提供依据和建议。     

The Salmonella mutagenicity of urban airborne particulate matter (PM2.5) from eight sites of the Emilia-Romagna regional monitoring network (Italy)

ARPA Emilia Romagna created, in 1997, a regional network for the continuous monitoring of the mutagenicity of PM(2.5) by short-term mutagenicity bioassays to guarantee a constant surveillance on the entire regional territory. The continuous monitoring of the PM mutagenicity provides essential information for a better understanding of the impact of air pollution on the health of the population, and allows one to better judge the efficiency of national and local efforts for urban air quality improvement (use of "green" petrol and ecodiesel, days during which traffic is prohibited, etc.). This article presents the results relating to the Network's activity between September 2000 and December 2002, on PM(2.5) fraction. The organic extracts of PM(2.5) were tested for mutagenicity using Salmonella tester strains TA98 and TA100 with and without metabolic activation (S9). The data obtained on the genotoxicity of air particulate extracts have revealed a constant presence of mutagenic substances adsorbed on particulate matter-with a prevalence of direct-acting mutagens than of promutagens-in a typical seasonal trend featuring higher levels in autumn-winter and lower in warmer periods of the year. In this work the evolution of PM(2.5) mutagenicity was compared with the particles, carbon monoxide (CO) and nitrogen dioxide (NO(2)) concentrations (monthly average); these comparisons revealed a quite good level of agreement on a local basis.     

Quantification of the impact of cooking processes on indoor concentrations of volatile organic species and primary and secondary organic aerosols

Cooking is recognized as an important source of particulate pollution in indoor and outdoor environments. We conducted more than 100 individual experiments to characterize the particulate and non‐methane organic gas emissions from various cooking processes, their reaction rates, and their secondary organic aerosol yields. We used this emission data to develop a box model, for simulating the cooking emission concentrations in a typical European home and the indoor gas‐phase reactions leading to secondary organic aerosol production. Our results suggest that about half of the indoor primary organic aerosol emission rates can be explained by cooking. Emission rates of larger and unsaturated aldehydes likely are dominated by cooking while the emission rates of terpenes are negligible. We found that cooking dominates the particulate and gas‐phase air pollution in non‐smoking European households exceeding 1000 μg m^?3. While frying processes are the main driver of aldehyde emissions, terpenes are mostly emitted due to the use of condiments. The secondary aerosol production is negligible with around 2 μg m^?3. Our results further show that ambient cooking organic aerosol concentrations can only be explained by super‐polluters like restaurants. The model offers a comprehensive framework for identifying the main parameters controlling indoor gas‐ and particle‐phase concentrations.     

A review on reducing indoor particulate matter concentrations from personal-level air filtration intervention under real-world exposure situations

Improving air quality in indoor environments where people live is of importance to protect human health. In this systematic review, we assessed the effectiveness of personal-level use of air filtration units in reducing indoor particulate matters (PM) concentrations under real-world situations following systematic review guidelines. A total of 54 articles were included in the review, in which 20 randomized controlled/crossover trials that reported the changes in indoor fine PM (PM_2.5) concentrations were quantitatively assessed in meta-analysis. Standardized mean differences (SMDs) were calculated for changes in indoor PM concentrations following air filtration interventions. Moderate-to-large reductions of 11%–82% in indoor PM_2.5 concentrations were observed with SMD of −1.19 (95% CI: −1.50, −0.88). The reductions in indoor PM concentrations varied by geographical locations, filtration technology employed, indoor environmental characteristics, and air pollution sources. Most studies were graded with low-to-moderate risk of bias; however, the overall certainty of evidence for indoor PM concentration reductions was graded at very low level. Considering the effectiveness of indoor air filtration under practical uses, socio-economic disparities across study populations, and costs of air filter replacement over time, our results highlight the importance of reducing air pollution exposure at the sources.     

The spatial and temporal variations in PM10 mass from six UK homes

People spend the majority of their time indoors mostly in the domestic environment, where their health may be effected by significant airborne particulate pollution. The indoor/outdoor air quality at six homes in Wales and Cornwall was investigated, based on different locations (urban, suburban, rural) and household characteristics (smokers, non-smokers). The spatial and temporal variations in PM10 mass were monitored for a calendar year, including ambient weather conditions. The activities of individuals within a household were also recorded. Monitoring of PM10 took place inside (kitchen, living room, bedroom) homes, along with concomitant collections outdoors. Samples were subjected to gravimetric analysis to determine PM10 concentrations and examined by scanning electron microscopy to identify the types of particles present on the filters. The results of the study show there are greater masses of PM10 indoors, and that the composition of the indoor PM10 is controlled by outdoor sources, and to a lesser extent by indoor anthropogenic activities, except in the presence of tobacco smokers. The indoor and outdoor PM10 collected was characterised as being a heterogeneous mixture of particles (soot, fibres, sea salt, smelter, gypsum, pollen and fungal spores).     

Can one use ambient air concentration data to estimate personal and population exposures to particles? An approach within the European EXPOLIS study

The objective of this paper is to devise a way to facilitate the use of fixed air monitors data in order to assess population exposure. A weighting scheme that uses the data from different monitoring sites and takes into account the time-activity patterns of the study population is proposed. PM2.5 personal monitoring data were obtained within the European EXPOLIS study, in Grenoble, France (40 adult non-smoking volunteers, winter 1997). Volunteers carried PM2.5 personal monitors during 48 h and filled in time-activity diaries. Workplaces and places of residence were classified into two categories using a Geographic Information System (GIS): some volunteers' life environments are seen as best represented by PM10 ambient air monitors located in urban background sites; others by monitors situated close to high traffic density sites (proximity sites). Measurements from the Grenoble fixed monitoring network using a TEOM PM10 sampler were available across the same period for these two types of sites (PM10block and PM10prox). These data were used to compute a translator parameter deltai that forces the measured PM2.5 personal exposures (PM2.5persoi) to equate the average PM10 urban ambient air concentrations ([PM10back + PM10prox]/2) measured the same days. Average deltai was 4.2 microg/m3 (CI95%[-3.4; 11.9]), with true average PM2.5 personal exposure being 36.2 microg/m3 (28.2; 44.1). PM10 ambient levels at the proximity site and at the background site were respectively PM10prox = 43.8 microg/m3 (37.1; 50.6) and PM10back = 37.0 microg/m3 (31.8; 42.3). In order to assess the consistency of this approach, six scenarios of 'proximity' and 'background' environments were accommodated, according to traffic intensity and road distance. Deltai was estimated for the entire EXPOLIS population and for subgroups, using terciles based on the percentage of time spent in proximity by each subject. Other similar studies need to be conducted in different urban settings, and with other pollutants, in order to assess the generalizability of this simple approach to estimate population exposures from air quality surveillance data.     

The adverse effects of fine particle air pollution on respiratory function in the elderly

There is increasing concern that airborne particles are critical risk factors for adverse health conditions in susceptible populations. The objective of this panel study is to investigate an association between particulate matter and the peak expiratory flow rate (PEFR) in the elderly and to compare estimated risks using PM10 or PM2.5 levels as a measure of exposure. During a 2-year longitudinal follow-up study, we contacted subjects living in an asylum for the elderly, provided them with a mini-Wright peak flow meter, and instructed to record all the flow readings, any respiratory symptoms, passive smoking activity, and hours spent outdoors for that given day. Daily levels of particulate matter were measured by two separate mini-volume air samplers (for PM10 and PM2.5) placed on the rooftop of the two-story residence asylum building. In our statistical models, we assumed that the expected response varied linearly for each participant with a slope and intercept that depended on fixed or time-varying covariates using a mixed linear model. The daily mean levels of PM10 and PM2.5 were 78 microg/m3 and 56 microg/m3, respectively. For every 10 microg/m3 increase in PM10 and PM2.5 levels, there was an estimated PEFR change of -0.39 l/min (95% CI, -0.63, -0.14) and -0.54 l/min (95% CI, -0.89, -0.19), respectively. These data also suggest that fine particles have a more adverse respiratory health impact for sensitive individuals such as the elderly and that more research and control strategies should focus on the smaller particles associated with air pollution.