不同粒径大气颗粒物与死亡终点关系的流行病学研究回顾

越来越多的国内外流行病学调查与研究发现,大气颗粒物的暴露与居民不同疾病死亡率的上升存在着显著的相关关系。本文就不同粒径颗粒物与最严重的健康终点——死亡之间关系的流行病学研究,进行较为系统的回顾和评述。指出:大多数研究就可吸入颗粒物(PM10)对死亡终点的影响已进行了较为系统和深入的探讨,目前研究重点向细颗粒物(PM2.5)对健康终点的影响转移。而粗颗粒物(PM10~2.5)以及与PM2.5之间的比较性研究资料还较为有限。超细颗粒物(PM0.1)的暴露及健康影响数据也很有限。但由于其数量浓度的优势,可能会成为未来流行病学研究的重点。     

Acute Effects of Ambient Particulate Matter on Mortality in Europe and North America: Results from the APHENA Study

Background

The APHENA (Air Pollution and Health: A Combined European and North American Approach) study is a collaborative analysis of multicity time-series data on the effect of air pollution on population health, bringing together data from the European APHEA (Air Pollution and Health: A European Approach) and U.S. NMMAPS (National Morbidity, Mortality and Air Pollution Study) projects, along with Canadian data.

Objectives

The main objective of APHENA was to assess the coherence of the findings of the multicity studies carried out in Europe and North America, when analyzed with a common protocol, and to explore sources of possible heterogeneity. We present APHENA results on the effects of particulate matter (PM) ≤ 10 μm in aerodynamic diameter (PM₁₀) on the daily number of deaths for all ages and for those < 75 and ≥ 75 years of age. We explored the impact of potential environmental and socioeconomic factors that may modify this association.

Methods

In the first stage of a two-stage analysis, we used Poisson regression models, with natural and penalized splines, to adjust for seasonality, with various degrees of freedom. In the second stage, we used meta-regression approaches to combine time-series results across cites and to assess effect modification by selected ecologic covariates.

Results

Air pollution risk estimates were relatively robust to different modeling approaches. Risk estimates from Europe and United States were similar, but those from Canada were substantially higher. The combined effect of PM₁₀ on all-cause mortality across all ages for cities with daily air pollution data ranged from 0.2% to 0.6% for a 10-μg/m³ increase in ambient PM₁₀ concentration. Effect modification by other pollutants and climatic variables differed in Europe and the United States. In both of these regions, a higher proportion of older people and higher unemployment were associated with increased air pollution risk.

Conclusions

Estimates of the increased mortality associated with PM air pollution based on the APHENA study were generally comparable with results of previous reports. Overall, risk estimates were similar in Europe and in the United States but higher in Canada. However, PM₁₀ effect modification patterns were somewhat different in Europe and the United States.     

灰霾天气细颗粒物对人支气管上皮细胞凋亡的影响

[目的]探讨灰霾天气细颗粒物（PM2.5）对人支气管上皮细胞（human bronchial epithelial cells,16-HBE）凋亡的影响。[方法]分别以8、16、32、64、128μg/mL浓度的PM2.5作用于16-HBE 24、48、72h,检测PM2.5对16-HBE细胞存活率及凋亡率的影响。[结果]染毒24、48、72h后,64、128μg/mL组细胞存活率均明显低于对照组（P〈0.05）,细胞凋亡率均明显高于对照组（P〈0.05）;72h各浓度组细胞存活率均低于24h相应处理组（P〈0.05）,当染毒浓度大于8μg/mL时,72h各浓度组细胞总凋亡率与24h相比均明显增加（P〈0.05）。[结论]灰霾天气细颗粒物PM2.5对16-HBE具有细胞毒性,能诱导其凋亡,且具有剂量和时间反应关系。     

The Temporal Lag Structure of Short-term Associations of Fine Particulate Matter Chemical Constituents and Cardiovascular and Respiratory Hospitalizations

Background: In air pollution time-series studies, the temporal pattern of the association of fine particulate matter (PM2.5; particulate matter ≤ 2.5 μm in aerodynamic diameter) and health end points has been observed to vary by disease category. The lag pattern of PM2.5 chemical constituents has not been well investigated, largely because daily data have not been available.Objectives: We explored the lag structure for hospital admissions using daily PM2.5 chemical constituent data for 5 years in the Denver Aerosol Sources and Health (DASH) study.Methods: We measured PM2.5 constituents, including elemental carbon, organic carbon, sulfate, and nitrate, at a central residential site from 2003 through 2007 and linked these daily pollution data to daily hospital admission counts in the five-county Denver metropolitan area. Total hospital admissions and subcategories of respiratory and cardiovascular admissions were examined. We assessed the lag structure of relative risks (RRs) of hospital admissions for PM2.5 and four constituents on the same day and from 1 to 14 previous days from a constrained distributed lag model; we adjusted for temperature, humidity, longer-term temporal trends, and day of week using a generalized additive model.Results: RRs were generally larger at shorter lags for total cardiovascular admissions but at longer lags for total respiratory admissions. The delayed lag pattern was particularly prominent for asthma. Elemental and organic carbon generally showed more immediate patterns, whereas sulfate and nitrate showed delayed patterns.Conclusion: In general, PM2.5 chemical constituents were found to have more immediate estimated effects on cardiovascular diseases and more delayed estimated effects on respiratory diseases, depending somewhat on the constituent.     

California Wildfires of 2008: Coarse and Fine Particulate Matter Toxicity

Background

During the last week of June 2008, central and northern California experienced thousands of forest and brush fires, giving rise to a week of severe fire-related particulate air pollution throughout the region. California experienced PM_10–2.5 (particulate matter with mass median aerodynamic diameter > 2.5 μm to < 10 μm; coarse ) and PM_2.5 (particulate matter with mass median aerodynamic diameter < 2.5 μm; fine) concentrations greatly in excess of the air quality standards and among the highest values reported at these stations since data have been collected.

Objectives

These observations prompt a number of questions about the health impact of exposure to elevated levels of PM_10–2.5 and PM_2.5 and about the specific toxicity of PM arising from wildfires in this region.

Methods

Toxicity of PM_10–2.5 and PM_2.5 obtained during the time of peak concentrations of smoke in the air was determined with a mouse bioassay and compared with PM samples collected under normal conditions from the region during the month of June 2007.

Results

Concentrations of PM were not only higher during the wildfire episodes, but the PM was much more toxic to the lung on an equal weight basis than was PM collected from normal ambient air in the region. Toxicity was manifested as increased neutrophils and protein in lung lavage and by histologic indicators of increased cell influx and edema in the lung.

Conclusions

We conclude that the wildfire PM contains chemical components toxic to the lung, especially to alveolar macrophages, and they are more toxic to the lung than equal doses of PM collected from ambient air from the same region during a comparable season.     

成都市公共场所集中空调通风系统可吸入颗粒物污染现状分析

目的了解成都市公共场所集_中空调通风系统送风中可吸入颗粒物（PM10）污染现状,分析主要影响因素,探讨改善集中空调通风系统PM10污染状况的办法。方法对40家使用集中空调场所进行现场调查,检测通风系统送风中的PM10浓度。结果40家场所中有9家合格,合格率为22％,集中空调经过清洗的场所PM10浓度比未经过清洗的场所低（t=4．528,P=0．001）,但集中空调清洗和未清洗场所的合格率比较没有统计学意义（x2=2．634,P=0．105）。结论集中空调管道内的清洁状况仅是送风中PM10的一项影响因素;集中空调通风系统送风中PM10浓度受外部环境影响很大,要改善集中空调通风系统PM10污染状况,集中空调使用单位应在新风口位置和集中空调设施做一些改进。     

Global air quality and health co-benefits of mitigating near-term climate change through methane and black carbon emission controls

Background: Tropospheric ozone and black carbon (BC), a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter; PM_2.5), are associated with premature mortality and they disrupt global and regional climate.Objectives: We examined the air quality and health benefits of 14 specific emission control measures targeting BC and methane, an ozone precursor, that were selected because of their potential to reduce the rate of climate change over the next 20–40 years.Methods: We simulated the impacts of mitigation measures on outdoor concentrations of PM_2.5 and ozone using two composition-climate models, and calculated associated changes in premature PM_2.5- and ozone-related deaths using epidemiologically derived concentration–response functions.Results: We estimated that, for PM_2.5 and ozone, respectively, fully implementing these measures could reduce global population-weighted average surface concentrations by 23–34% and 7–17% and avoid 0.6–4.4 and 0.04–0.52 million annual premature deaths globally in 2030. More than 80% of the health benefits are estimated to occur in Asia. We estimated that BC mitigation measures would achieve approximately 98% of the deaths that would be avoided if all BC and methane mitigation measures were implemented, due to reduced BC and associated reductions of nonmethane ozone precursor and organic carbon emissions as well as stronger mortality relationships for PM_2.5 relative to ozone. Although subject to large uncertainty, these estimates and conclusions are not strongly dependent on assumptions for the concentration–response function.Conclusions: In addition to climate benefits, our findings indicate that the methane and BC emission control measures would have substantial co-benefits for air quality and public health worldwide, potentially reversing trends of increasing air pollution concentrations and mortality in Africa and South, West, and Central Asia. These projected benefits are independent of carbon dioxide mitigation measures. Benefits of BC measures are underestimated because we did not account for benefits from reduced indoor exposures and because outdoor exposure estimates were limited by model spatial resolution.     

Feasibility of assessing public health impacts of air pollution reduction programs on a local scale: New Haven case study

Background

New approaches to link health surveillance data with environmental and population exposure information are needed to examine the health benefits of risk management decisions.

Objective

We examined the feasibility of conducting a local assessment of the public health impacts of cumulative air pollution reduction activities from federal, state, local, and voluntary actions in the City of New Haven, Connecticut (USA).

Methods

Using a hybrid modeling approach that combines regional and local-scale air quality data, we estimated ambient concentrations for multiple air pollutants [e.g., PM_2.5 (particulate matter ≤ 2.5 μm in aerodynamic diameter), NO_x (nitrogen oxides)] for baseline year 2001 and projected emissions for 2010, 2020, and 2030. We assessed the feasibility of detecting health improvements in relation to reductions in air pollution for 26 different pollutant–health outcome linkages using both sample size and exploratory epidemiological simulations to further inform decision-making needs.

Results

Model projections suggested decreases (~ 10–60%) in pollutant concentrations, mainly attributable to decreases in pollutants from local sources between 2001 and 2010. Models indicated considerable spatial variability in the concentrations of most pollutants. Sample size analyses supported the feasibility of identifying linkages between reductions in NO_x and improvements in all-cause mortality, prevalence of asthma in children and adults, and cardiovascular and respiratory hospitalizations.

Conclusion

Substantial reductions in air pollution (e.g., ~ 60% for NO_x) are needed to detect health impacts of environmental actions using traditional epidemiological study designs in small communities like New Haven. In contrast, exploratory epidemiological simulations suggest that it may be possible to demonstrate the health impacts of PM reductions by predicting intraurban pollution gradients within New Haven using coupled models.     

Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application

Background

Epidemiologic and health impact studies of fine particulate matter with diameter < 2.5 μm (PM_2.5) are limited by the lack of monitoring data, especially in developing countries. Satellite observations offer valuable global information about PM_2.5 concentrations.

Objective

In this study, we developed a technique for estimating surface PM_2.5 concentrations from satellite observations.

Methods

We mapped global ground-level PM_2.5 concentrations using total column aerosol optical depth (AOD) from the MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multiangle Imaging Spectroradiometer) satellite instruments and coincident aerosol vertical profiles from the GEOS-Chem global chemical transport model.

Results

We determined that global estimates of long-term average (1 January 2001 to 31 December 2006) PM_2.5 concentrations at approximately 10 km × 10 km resolution indicate a global population-weighted geometric mean PM_2.5 concentration of 20 μg/m³. The World Health Organization Air Quality PM_2.5 Interim Target-1 (35 μg/m³ annual average) is exceeded over central and eastern Asia for 38% and for 50% of the population, respectively. Annual mean PM_2.5 concentrations exceed 80 μg/m³ over eastern China. Our evaluation of the satellite-derived estimate with ground-based in situ measurements indicates significant spatial agreement with North American measurements (r = 0.77; slope = 1.07; n = 1057) and with noncoincident measurements elsewhere (r = 0.83; slope = 0.86; n = 244). The 1 SD of uncertainty in the satellite-derived PM_2.5 is 25%, which is inferred from the AOD retrieval and from aerosol vertical profile errors and sampling. The global population-weighted mean uncertainty is 6.7 μg/m³.

Conclusions

Satellite-derived total-column AOD, when combined with a chemical transport model, provides estimates of global long-term average PM_2.5 concentrations.     

Predicting Chronic Fine and Coarse Particulate Exposures Using Spatiotemporal Models for the Northeastern and Midwestern United States

Background

Chronic epidemiologic studies of particulate matter (PM) are limited by the lack of monitoring data, relying instead on citywide ambient concentrations to estimate exposures. This method ignores within-city spatial gradients and restricts studies to areas with nearby monitoring data. This lack of data is particularly restrictive for fine particles (PM with aerodynamic diameter < 2.5 μm; PM_2.5) and coarse particles (PM with aerodynamic diameter 2.5–10 μm; PM_10–2.5), for which monitoring is limited before 1999. To address these limitations, we developed spatiotemporal models to predict monthly outdoor PM_2.5 and PM_10–2.5 concentrations for the northeastern and midwestern United States.

Methods

For PM_2.5, we developed models for two periods: 1988–1998 and 1999–2002. Both models included smooth spatial and regression terms of geographic information system-based and meteorologic predictors. To compensate for sparse monitoring data, the pre-1999 model also included predicted PM₁₀ (PM with aerodynamic diameter < 10 μm) and extinction coefficients (km⁻¹). PM_10–2.5 levels were estimated as the difference in monthly predicted PM₁₀ and PM_2.5, with predicted PM₁₀ from our previously developed PM₁₀ model.

Results

Predictive performance for PM_2.5 was strong (cross-validation R² = 0.77 and 0.69 for post-1999 and pre-1999 PM_2.5 models, respectively) with high precision (2.2 and 2.7 μg/m³, respectively). Models performed well irrespective of population density and season. Predictive performance for PM_10–2.5 was weaker (cross-validation R² = 0.39) with lower precision (5.5 μg/m³). PM_10–2.5 levels exhibited greater local spatial variability than PM₁₀ or PM_2.5, suggesting that PM_2.5 measurements at ambient monitoring sites are more representative for surrounding populations than for PM₁₀ and especially PM_10–2.5.

Conclusions

We provide semiempirical models to predict spatially and temporally resolved long-term average outdoor concentrations of PM_2.5 and PM_10–2.5 for estimating exposures of populations living in the northeastern and midwestern United States.     

Particulate air pollution and susceptibility to the development of pulmonary tuberculosis disease in North Carolina: an ecological study

Although Mycobacterium tuberculosis is the causative agent of pulmonary tuberculosis (PTB), environmental factors may influence disease progression. Ecologic studies conducted in countries outside the USA with high levels of air pollution and PTB have suggested a link between active disease and ambient air pollution. The present investigation is the first to examine the ambient air pollution-PTB association in a country, where air pollution levels are comparatively lower. We used Poisson regression models to examine the association of outdoor air pollutants, PM₁₀ and PM_2.5 with rates of PTB in North Carolina residents during 1993–2007. Results suggest a potential association between long-term exposure to particulate matter (PM) and PTB disease. In view of the high levels of air pollution and high rates of PTB worldwide, a potential association between ambient air pollution and tuberculosis warrants further study.     

The Effect of Fine and Coarse Particulate Air Pollution on Mortality: A National Analysis

Background

Although many studies have examined the effects of air pollution on mortality, data limitations have resulted in fewer studies of both particulate matter with an aerodynamic diameter of ≤ 2.5 μm (PM_2.5; fine particles) and of coarse particles (particles with an aerodynamic diameter > 2.5 and < 10 μm; PM coarse). We conducted a national, multicity time-series study of the acute effect of PM_2.5 and PM coarse on the increased risk of death for all causes, cardiovascular disease (CVD), myocardial infarction (MI), stroke, and respiratory mortality for the years 1999–2005.

Method

We applied a city- and season-specific Poisson regression in 112 U.S. cities to examine the association of mean (day of death and previous day) PM_2.5 and PM coarse with daily deaths. We combined the city-specific estimates using a random effects approach, in total, by season and by region.

Results

We found a 0.98% increase [95% confidence interval (CI), 0.75–1.22] in total mortality, a 0.85% increase (95% CI, 0.46–1.24) in CVD, a 1.18% increase (95% CI, 0.48–1.89) in MI, a 1.78% increase (95% CI, 0.96–2.62) in stroke, and a 1.68% increase (95% CI, 1.04–2.33) in respiratory deaths for a 10-μg/m³ increase in 2-day averaged PM_2.5. The effects were higher in spring. For PM coarse, we found significant but smaller increases for all causes analyzed.

Conclusions

We conclude that our analysis showed an increased risk of mortality for all and specific causes associated with PM_2.5, and the risks are higher than what was previously observed for PM₁₀. In addition, coarse particles are also associated with more deaths.     

Effects of Ambient Air Pollutants on Asthma Medication Use and Wheezing among Fourth-Grade School Children from 12 Southern California Communities Enrolled in The Children's Health Study

To investigate the effects of 12 monthly average air pollution levels on monthly prevalence of respiratory morbidity, the authors examined retrospective questionnaire data on 2034 4th-grade children from 12 Southern California communities that were enrolled in The Children's Health Study. Wheezing during the spring and summer months was associated with community levels of airborne particulate matter with a diameter ≤ 10 μm (PM₁₀) (odds ratio (OR) = 2.91; 95% confidence interval (Cl) = 1.46–5.80), but was not associated with community levels of ozone, nitrogen dioxide, PM_2.5 (diameter ≤ 2.5), nitric acid, or formic acid. Logistic regression was performed on data stratified into two seasonal groups, spring/summer and fall/winter. Among asthmatics, the monthly prevalence of asthma medication use was associated with monthly levels of ozone, nitric acid, and acetic acid (OR = 1.80 [95%Cl = 1.19–2.70]; OR = 1.80 [95%Cl = 1.23–2.65]; OR = 1.57 [95% Cl = 1.11–2.21]; respectively). Asthma medication use was more prevalent among children who spent more time outdoors—with consequential exposure to ozone—than among children who spent more time indoors (OR = 3.07 [95%Cl = 1.61–5.86]; OR = 1.31 [95%Cl = 0.47–2.71]; respectively). The authors concluded that monthly variations in some ambient air pollutants were associated with monthly respiratory morbidity among school children.     

Effects of Ambient Particulate Matter (PM2.5) Exposure on Calorie Intake and Appetite of Outdoor Workers

Malaysia has been experiencing smoke-haze episodes almost annually for the past few decades. PM_2.5 is the main component in haze and causes harmful impacts on health due to its small aerodynamic size. This study aimed to explore the implications of PM_2.5 exposure on the dietary intake of working individuals. Two phased 13-weeks follow-up study was conducted involving 440 participants, consisting of two cohorts of outdoor and indoor workers. Ambient PM_2.5 concentrations were monitored using DustTrakTM DRX Aerosol Monitor. Data on Simplified Nutritional Appetite Questionnaire (SNAQ) and 24 h diet recall were collected weekly. The highest PM_2.5 concentration of 122.90 ± 2.07 µg/m³ was recorded in August, and it vastly exceeded the standard value stipulated by US EPA and WHO. SNAQ scores and calorie intake were found to be significantly (p < 0.05) associated with changes in PM_2.5 exposure of outdoor workers. Several moderate and positive correlations (R-value ranged from 0.4 to 0.6) were established between SNAQ scores, calorie intake and PM_2.5 exposure. Overall findings suggested that long hours of PM_2.5 exposure affect personal dietary intake, potentially increasing the risk of metabolic syndromes and other undesired health conditions. The current policy should be strengthened to safeguard the well-being of outdoor workers.     

Blood Pressure Changes and Chemical Constituents of Particulate Air Pollution: Results from the Healthy Volunteer Natural Relocation (HVNR) Study

Background: Elevated blood pressure (BP) has been associated with particulate matter (PM) air pollution, but associations with PM chemical constituents are still uncertain.Objectives: We investigated associations of BP with various chemical constituents of fine PM (PM_2.5) during 460 repeated visits among a panel of 39 university students.Methods: Resting BP was measured using standardized methods before and after the university students relocated from a suburban campus to an urban campus with different air pollution contents in Beijing, China. Air pollution data were obtained from central monitors close to student residences. We used mixed-effects models to estimate associations of various PM_2.5 constituents with systolic BP (SBP), diastolic BP (DBP), and pulse pressure.Results: An interquartile range increase of 51.2 μg/m³ in PM_2.5 was associated with a 1.08-mmHg (95% CI: 0.17, 1.99) increase in SBP and a 0.96-mmHg (95% CI: 0.31, 1.61) increase in DBP on the following day. A subset of PM_2.5 constituents, including carbonaceous fractions (organic carbon and elemental carbon), ions (chloride and fluoride), and metals/metalloid elements (nickel, zinc, magnesium, lead, and arsenic), were found to have robust positive associations with different BP variables, though robust negative associations of manganese, chromium, and molybdenum with SBP or DBP also were observed.Conclusions: Our results support relationships between specific PM_2.5 constituents and BP. These findings have potential implications for the development of pollution abatement strategies that maximize public health benefits.     

Satellite-based Estimates of Ambient Air Pollution and Global Variations in Childhood Asthma Prevalence

Background: The effect of ambient air pollution on global variations and trends in asthma prevalence is unclear.Objectives: Our goal was to investigate community-level associations between asthma prevalence data from the International Study of Asthma and Allergies in Childhood (ISAAC) and satellite-based estimates of particulate matter with aerodynamic diameter < 2.5 μm (PM2.5) and nitrogen dioxide (NO2), and modelled estimates of ozone.Methods: We assigned satellite-based estimates of PM2.5 and NO2 at a spatial resolution of 0.1° × 0.1° and modeled estimates of ozone at a resolution of 1° × 1° to 183 ISAAC centers. We used center-level prevalence of severe asthma as the outcome and multilevel models to adjust for gross national income (GNI) and center- and country-level sex, climate, and population density. We examined associations (adjusting for GNI) between air pollution and asthma prevalence over time in centers with data from ISAAC Phase One (mid-1900s) and Phase Three (2001-2003).Results: For the 13- to 14-year age group (128 centers in 28 countries), the estimated average within-country change in center-level asthma prevalence per 100 children per 10% increase in center-level PM2.5 and NO2 was -0.043 [95% confidence interval (CI): -0.139, 0.053] and 0.017 (95% CI: -0.030, 0.064) respectively. For ozone the estimated change in prevalence per parts per billion by volume was -0.116 (95% CI: -0.234, 0.001). Equivalent results for the 6- to 7-year age group (83 centers in 20 countries), though slightly different, were not significantly positive. For the 13- to 14-year age group, change in center-level asthma prevalence over time per 100 children per 10% increase in PM2.5 from Phase One to Phase Three was -0.139 (95% CI: -0.347, 0.068). The corresponding association with ozone (per ppbV) was -0.171 (95% CI: -0.275, -0.067).Conclusion: In contrast to reports from within-community studies of individuals exposed to traffic pollution, we did not find evidence of a positive association between ambient air pollution and asthma prevalence as measured at the community level.     

PM2.5对大鼠肝、脾、肾组织的氧化损伤效应

目的探讨PMU对大鼠肝、脾、肾组织抗氧化酶活力和脂质过氧化（LPO）水平的影响。方法选取32只雄性Wistar大鼠,随机分为4组,分别用0、1．5、7．5、37．5mg／kg的PMu经气管注入染毒后24h处死大鼠,测定肝、脾、肾组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GSH—Px）活力,谷胱甘肽（GSH）和硫代巴比妥酸反应物（TBARS）含量。结果PM”染毒组大鼠肝、肾组织内SOD、CAT、GSH—Px活力和SOD／TBARS比值均较对照组降低（P〈0．05,P〈0．01）,具有剂量一效应关系。各染毒组TBARS／GSH—Px比值较对照组显著升高（P〈0．01,P〈0．001）。染毒组脾、肾组织GSH含量较对照组显著下降（P〈0．05,P〈0．01）,而染毒组肝组织GSH含量则出现先升高后降低的非线性变化特征（P〈0．01,P〈0．05）。染毒组肝组织LPO水平出现剂量-效应性升高（P〈0．05）,染毒组脾组织各种抗氧化酶活力、LPO水平和TBARS／GSH—Px比值均未见显著变化。结论PM2.5可引起大鼠肝、肾组织的氧化损伤。     

PM_(2.5)对大鼠肝、脾、肾组织的氧化损伤效应

目的探讨PM2.5对大鼠肝、脾、肾组织抗氧化酶活力和脂质过氧化(LPO)水平的影响。方法选取32只雄性Wistar大鼠,随机分为4组,分别用0、1.5、7.5、37.5mg/kg的PM2.5经气管注入染毒后24h处死大鼠,测定肝、脾、肾组织超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活力,谷胱甘肽(GSH)和硫代巴比妥酸反应物(TBARS)含量。结果PM2.5染毒组大鼠肝、肾组织内SOD、CAT、GSH-Px活力和SOD/TBARS比值均较对照组降低(P<0.05,P<0.01),具有剂量-效应关系。各染毒组TBARS/GSH-Px比值较对照组显著升高(P<0.01,P<0.001)。染毒组脾、肾组织GSH含量较对照组显著下降(P<0.05,P<0.01),而染毒组肝组织GSH含量则出现先升高后降低的非线性变化特征(P<0.01,P<0.05)。染毒组肝组织LPO水平出现剂量-效应性升高(P<0.05),染毒组脾组织各种抗氧化酶活力、LPO水平和TBARS/GSH-Px比值均未见显著变化。结论PM2.5可引起大鼠肝、肾组织的氧化损伤。     

Hierarchical spatial modeling of uncertainty in air pollution and birth weight study

In environmental health studies air pollution measurements from the closest monitor are commonly used as a proxy for personal exposure. This technique assumes that air pollution concentrations are spatially homogeneous in the neighborhoods associated with the monitors and consequently introduces measurement error into a resultant model. To model the relationship between maternal exposure to air pollution and birth weight, we build a hierarchical model that accounts for the associated measurement error. We allow four possible scenarios, with increasing flexibility, for capturing this uncertainty. In the two simplest cases, we specify models with a constant variance term and a variance component that allows uncertainty in the exposure measurements to increase as the distance between maternal residence and the location of the closest monitor increases. In the remaining two models, we introduce spatial dependence using random effects. The models are illustrated using Bayesian hierarchical modeling techniques that relate pregnancy outcomes from the North Carolina Detailed Birth Records to air pollution data from the U.S. Environmental Protection Agency.     

Air pollution and acute respiratory response in a panel of asthmatic children along the U.S.-Mexico border

Background: Concerns regarding the health impact of urban air pollution on asthmatic children are pronounced along the U.S.–Mexico border because of rapid population growth near busy border highways and roads.Objectives: We conducted the first binational study of the impacts of air pollution on asthmatic children in Ciudad Juarez, Mexico, and El Paso, Texas, USA, and compared different exposure metrics to assess acute respiratory response.Methods: We recruited 58 asthmatic children from two schools in Ciudad Juarez and two schools in El Paso. A marker of airway inflammation [exhaled nitric oxide (eNO)], respiratory symptom surveys, and pollutant measurements (indoor and outdoor 48-hr size-fractionated particulate matter, 48-hr black carbon, and 96-hr nitrogen dioxide) were collected at each school for 16 weeks. We examined associations between the pollutants and respiratory response using generalized linear mixed models.Results: We observed small but consistent associations between eNO and numerous pollutant metrics, with estimated increases in eNO ranging from 1% to 3% per interquartile range increase in pollutant concentrations. Effect estimates from models using school-based concentrations were generally stronger than corresponding estimates based on concentrations from ambient air monitors. Both traffic-related and non–traffic-related particles were typically more robust predictors of eNO than was nitrogen dioxide, for which associations were highly sensitive to model specification. Associations differed significantly across the four school-based cohorts, consistent with heterogeneity in pollutant concentrations and cohort characteristics. Models examining respiratory symptoms were consistent with the null.Conclusions: The results indicate adverse effects of air pollution on the subclinical respiratory health of asthmatic children in this region and provide preliminary support for the use of air pollution monitors close to schools to track exposure and potential health risk in this population.