空气污染与儿童哮喘发病机制的研究进展

我国多地区雾霾严重,空气质量堪忧。大气污染成因复杂,大气颗粒物的来源更为复杂多变。常见的空气污染物种类繁多,如交通相关空气污染物、多环芳香烃、香烟烟雾、尘埃颗粒及细颗粒物 PM2.5,均与儿童哮喘密切相关,其毒性组分和致毒机制尚不明确,健康效应和毒理机制已经成为前沿的科学热点问题之一。本文就近几年来关于空气污染加重或引起儿童哮喘的机制进行综合分析。     

Personal exposures to traffic-related air pollution and acute respiratory health among Bronx schoolchildren with asthma

Background

Previous studies have reported relationships between adverse respiratory health outcomes and residential proximity to traffic pollution, but have not shown this at a personal exposure level.

Objective

We compared, among inner-city children with asthma, the associations of adverse asthma outcome incidences with increased personal exposure to particulate matter mass ≤ 2.5 μm in aerodynamic diameter (PM_2.5) air pollution versus the diesel-related carbonaceous fraction of PM_2.5.

Methods

Daily 24-hr personal samples of PM_2.5, including the elemental carbon (EC) fraction, were collected for 40 fifth-grade children with asthma at four South Bronx schools (10 children per school) during approximately 1 month each. Spirometry and symptom scores were recorded several times daily during weekdays.

Results

We found elevated same-day relative risks of wheeze [1.45; 95% confidence interval (CI), 1.03–2.04)], shortness of breath (1.41; 95% CI, 1.01–1.99), and total symptoms (1.30; 95% CI, 1.04–1.62) with an increase in personal EC, but not with personal PM_2.5 mass. We found increased risk of cough, wheeze, and total symptoms with increased 1-day lag and 2-day average personal and school-site EC. We found no significant associations with school-site PM_2.5 mass or sulfur. The EC effect estimate was robust to addition of gaseous pollutants.

Conclusion

Adverse health associations were strongest with personal measures of EC exposure, suggesting that the diesel “soot” fraction of PM_2.5 is most responsible for pollution-related asthma exacerbations among children living near roadways. Studies that rely on exposure to PM mass may underestimate PM health impacts.     

上海市大气污染对小学生肺功能小气道指标的急性效应研究

目的 分析上海市复合型大气污染对儿童肺功能小气道指标的急性影响。方法 在上海市内环、中环和外环各选择一所小学（A、B和C）,每所学校各随机抽取3~5年级一个班级学生为研究对象（共233人）;A、B两校于2013年12月和C校于2014年12月测试肺功能3次,各校分别于次年5-6月测试第4次肺功能。同时收集同期三校就近环境空气质量监测点大气细颗粒物（PM_2.5）、可吸入颗粒物（PM₁₀）、二氧化硫（SO₂）和二氧化氮（NO₂）污染物数据和气象监测数据;采用线性混合效应模型分析大气污染对肺功能小气道指标的影响。结果 控制气象因素和个体因素后,PM_2.5、PM₁₀滞后2 d和累计滞后2 d、SO₂累计滞后2 d和NO₂检测当日浓度每增加一个四分位间距（IQR）,儿童25%肺活量最大呼吸流速（MEF_25%）、50%肺活量最大呼吸流速（MEF_50%）、75%肺活量最大呼吸流速（MEF_75%）和用力呼气中段流速（FEF_25%~75%）均有不同程度的降低（P<0.05或P<0.01）;双污染物模型分析显示SO₂和NO₂分别叠加PM_2.5和PM₁₀污染时,滞后效应值大于SO₂和NO₂单独存在时（P<0.05）。结论 上海市大气污染物短期暴露与儿童肺功能小气道指标变化呈负相关,并存在滞后效应及累计滞后效应。     

Circulating biomarkers of inflammation, antioxidant activity, and platelet activation are associated with primary combustion aerosols in subjects with coronary artery disease

BACKGROUND: Biomarkers of systemic inflammation have been associated with risk of cardiovascular morbidity and mortality. OBJECTIVES: We aimed to clarify associations of particulate matter (PM) air pollution with systemic inflammation using models based on size-fractionated PM mass and markers of primary and secondary aerosols. METHODS: We followed a panel of 29 nonsmoking elderly subjects with a history of coronary artery disease (CAD) living in retirement communities in the Los Angeles, California, air basin. Blood plasma biomarkers were measured weekly over 12 weeks and included C-reactive protein (CRP), fibrinogen, tumor necrosis factor-alpha (TNF-alpha) and its soluble receptor-II (sTNF-RII), interleukin-6 (IL-6) and its soluble receptor (IL-6sR), fibrin D-dimer, soluble platelet selectin (sP-selectin), soluble vascular cell adhesion molecule-1 (sVCAM-1), intracellular adhesion molecule-1 (sICAM-1), and myeloperoxidase (MPO). To assess changes in antioxidant capacity, we assayed erythrocyte lysates for glutathione peroxidase-1 (GPx-1) and copper-zinc superoxide dismutase (Cu,Zn-SOD) activities. We measured indoor and outdoor home daily size-fractionated PM mass, and hourly pollutant gases, total particle number (PN), fine PM elemental carbon (EC) and organic carbon (OC), estimated secondary organic aerosol (SOA) and primary OC (OCpri) from total OC, and black carbon (BC). We analyzed data with mixed models controlling for temperature and excluding weeks with infections. RESULTS: We found significant positive associations for CRP, IL-6, sTNF-RII, and sP-selectin with outdoor and/or indoor concentrations of quasi-ultrafine PM < or = 0.25 microm in diameter, EC, OCpri, BC, PN, carbon monoxide, and nitrogen dioxide from the current-day and multiday averages. We found consistent positive but largely nonsignificant coefficients for TNF-alpha, sVCAM-1, and sICAM-1, but not fibrinogen, IL-6sR, or D-dimer. We found inverse associations for erythrocyte Cu,Zn-SOD with these pollutants and other PM size fractions (0.25-2.5 and 2.5-10 microm). Inverse associations of GPx-1 and MPO with pollutants were largely nonsignificant. Indoor associations were often stronger for estimated indoor EC, OCpri, and PN of outdoor origin than for uncharacterized indoor measurements. There was no evidence for positive associations with SOA. CONCLUSIONS: Results suggest that traffic emission sources of OCpri and quasi-ultrafine particles lead to increased systemic inflammation and platelet activation and decreased antioxidant enzyme activity in elderly people with CAD.     

大气污染与儿童哮喘研究文献计量学分析

目的 分析大气污染与儿童哮喘研究,为后期开展深入研究提供借鉴和指导。方法 采用文献计量和数据图谱可视化分析,以2000-2017年Science Citation Index Expanded数据库收录论文为研究对象,从发表和被引时间序列、国家、学科和期刊、研究机构和作者、论文关键词5个方面统计分析。结果 论文发表数量和被引次数随时间快速上升;80%高质量杂志和60%研究机构来自美国;期刊发表文献数量与其影响因子线性相关无统计学意义(r=0.39, P=0.221);91%论文来自环境科学和过敏学;出生队列和细颗粒物为近年研究热点。结论 大气污染与儿童哮喘研究处于增长期,美国主导该领域研究,研究重点从单一污染物与儿童哮喘关系向复合空气污染和生命历程流行病学扩展。     

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.     

Ambient air pollution and birth weight in full-term infants in Atlanta, 1994-2004

Background

An emerging body of evidence suggests that ambient levels of air pollution during pregnancy are associated with fetal growth.

Objectives

We examined relationships between birth weight and temporal variation in ambient levels of carbon monoxide, nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone, particulate matter ≤ 10 μm in diameter (PM₁₀), ≤ 2.5 μm (PM_2.5), 2.5 to 10 μm (PM_2.5–10), and PM_2.5 chemical component measurements for 406,627 full-term births occurring between 1994 and 2004 in five central counties of metropolitan Atlanta.

Methods

We assessed relationships between birth weight and pollutant concentrations during each infant’s first month of gestation and third trimester, as well as in each month of pregnancy using distributed lag models. We also conducted capture-area analyses limited to mothers residing within 4 miles (6.4 km) of each air quality monitoring station.

Results

In the five-county analysis, ambient levels of NO₂, SO₂, PM_2.5 elemental carbon, and PM_2.5 water-soluble metals during the third trimester were significantly associated with small reductions in birth weight (−4 to −16 g per interquartile range increase in pollutant concentrations). Third-trimester estimates were generally higher in Hispanic and non-Hispanic black infants relative to non-Hispanic white infants. Distributed lag models were also suggestive of associations between air pollutant concentrations in late pregnancy and reduced birth weight. The capture-area analyses provided little support for the associations observed in the five-county analysis.

Conclusions

Results provide some support for an effect of ambient air pollution in late pregnancy on birth weight in full-term infants.     

Effects of ambient air pollution on pulmonary function among schoolchildren

Literature has shown adverse effects of ambient air pollution exposure on various asthma related outcomes in childhood. However, the associated evidence on pulmonary function effects is still inconsistent.We conducted a population-based study comprised of seventh-grade children in 14 Taiwanese communities. Pulmonary function tests and questionnaires were completed on 3957 subjects. We evaluated the effects of ambient air pollution exposures based on the data collected in 2005–2007 by existing air monitoring stations. Multiple linear mixed effect models were fitted to estimate the relationship between community pollutant levels and pulmonary function indices. After adjustment for individual-level confounders, pulmonary function differed only slightly between communities with different levels of air pollution. We found greater effects of ambient air pollutants on pulmonary function for boys than for girls. Among boys, traffic-related pollutants CO, NOx, NO₂, and NO were generally associated with chronic adverse effects on FVC and FEV₁, and subchronic adverse effects mainly on maximal mid-expiratory flow (MMEF) and peak expiratory flow rate. Among girls, only NOx and NO₂ showed subchronic adverse effects on MMEF. Although effect estimates of SO₂, PM₁₀, and PM_2.5 were generally negative for boys, none achieved statistical significance.Our data suggests that ambient traffic-related pollution had chronic adverse effects on pulmonary function in schoolchildren, especially for boys.     

Acute effects of urban ambient air pollution on respiratory symptoms, asthma medication use, and doctor visits for asthma in a cohort of Australian children

We enrolled a cohort of primary school children with a history of wheeze (n=148) in an 11-month longitudinal study to examine the relationship between ambient air pollution and respiratory morbidity. We obtained daily air pollution (ozone, particulate matter less than 10 microm, and nitrogen dioxide), meteorological, and pollen data. One hundred twenty-five children remained in the final analysis. We used logistic regression models to determine associations between air pollution and respiratory symptoms, asthma medication use, and doctor visits for asthma. There were no associations between ambient ozone concentrations and respiratory symptoms, asthma medication use, and doctor visits for asthma. There was, however, an association between PM(10) concentrations and doctor visits for asthma (RR=1.11, 95% CI=1.04-1.19) and between NO(2) concentration and wet cough (RR=1.05, 95% CI=1.003-1.10) in single-pollutant models. The associations remained significant in multipollutant models. There was no consistent evidence that children with wheeze, positive histamine challenge, and doctor diagnosis of asthma reacted differently to air pollution from children with wheeze and doctor diagnosis of asthma and children with wheeze only. There were significant associations between PM(10) levels and doctor visits for asthma and an association between NO(2) levels and the prevalence of wet cough. We were, however, unable to demonstrate that current levels of ambient air pollution in western Sydney have a coherent range of adverse health effects on children with a history of wheezing.     

煤烟型大气污染对儿童肺功能的影响

为观察煤烟型大气污染对儿童健康的影响 ,选择了太原市 3个污染程度不同地区的 45 0名儿童进行肺功能测试和问卷调查。研究结果显示 ,儿童呼吸功能表现为重度污染区 <中度污染区 <相对清洁区 ;肺通气功能阻塞性异常率表现为重度污染区 >中度污染区 >相对清洁区 ;Logistic回归分析发现肺通气功能阻塞性异常率与小学生家庭的取暖方式、厨房和卧室是否分开以及污染物的水平有关 ;多元线性回归分析显示重度污染区儿童的FVC、FEF5 0与相对清洁区相比分别减少了 65 80ml、119 2 7ml,中度污染区儿童的FVC、FEF5 0与相对清洁区相比分别减少了 5 7 2 8ml和 114 2 9ml;Ln(SO2 )每升高一个单位 ,FVC和FEF5 0分别减少69 10ml和 119 79ml,Ln(PM1 0 )每升高一个单位 ,FVC、FEF5 0等分别减少了 193 5 0ml和 171 69ml。结果提示 ,太原市煤烟型大气污染对儿童呼吸系统产生了危害。     

Ambient air pollution and apnea and bradycardia in high-risk infants on home monitors

Background: Evidence suggests that increased ambient air pollution concentrations are associated with health effects, although relatively few studies have specifically examined infants.Objective: We examined associations of daily ambient air pollution concentrations with central apnea (prolonged pauses in breathing) and bradycardia (low heart rate) events among infants prescribed home cardiorespiratory monitors.Methods: The home monitors record the electrocardiogram, heart rate, and respiratory effort for detected apnea and bradycardia events in high-risk infants [primarily premature and low birth weight (LBW) infants]. From August 1998 through December 2002, 4,277 infants had 8,960 apnea event-days and 29,450 bradycardia event-days in > 179,000 days of follow-up. We assessed the occurrence of apnea and bradycardia events in relation to speciated particulate matter and gaseous air pollution levels using a 2-day average of air pollution (same day and previous day), adjusting for temporal trends, temperature, and infant age.Results: We observed associations between bradycardia and 8-hr maximum ozone [odds ratio (OR) = 1.049 per 25-ppb increase; 95% confidence interval (CI), 1.021–1.078] and 1-hr maximum nitrogen dioxide (OR =1.025 per 20-ppb increase; 95% CI, 1.000–1.050). The association with ozone was robust to different methods of control for time trend and specified correlation structure. In secondary analyses, associations of apnea and bradycardia with pollution were generally stronger in infants who were full term and of normal birth weight than in infants who were both premature and LBW.Conclusions: These results suggest that higher air pollution concentrations may increase the occurrence of apnea and bradycardia in high-risk infants.     

Effects of particulate air pollution on nasal and lung function development among Greek children: a 19-year cohort study

The aim was to investigate respiratory symptoms, lung function and nasal airflow development among a cohort of children who were exposed to particulate air pollution. We used questionnaires, spirometry and rhinomanometry, while central-monitored PM₁₀ concentrations were used for exposure assessment. We initially examined 1046 children (10–12 year old) in the heavily polluted town of Ptolemaida, Greece, and 379 children in the cleaner town of Grevena (control group). We re-evaluated 312 of the former and 119 of the latter after 19 years. PM₁₀ concentrations were above permissible levels in Ptolemaida during all study period. At both visits, nasal flow was significantly lower in the study sample. At the follow-up visit, 34.3?% had severe nasal obstruction (相似文献   

Personal and ambient air pollution is associated with increased exhaled nitric oxide in children with asthma

BACKGROUND: Research has shown associations between pediatric asthma outcomes and airborne particulate matter (PM). The importance of particle components remains to be determined. METHODS: We followed a panel of 45 schoolchildren with persistent asthma living in Southern California. Subjects were monitored over 10 days with offline fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation. Personal active sampler exposures included continuous particulate matter < 2.5 microm in aerodynamic diameter (PM2.5), 24-hr PM2.5 elemental and organic carbon (EC, OC), and 24-hr nitrogen dioxide. Ambient exposures included PM2.5, PM2.5 EC and OC, and NO2. Data were analyzed with mixed models controlling for personal temperature, humidity and 10-day period. RESULTS: The strongest positive associations were between FeNO and 2-day average pollutant concentrations. Per interquartile range pollutant increase, these were: for 24 microg/m3 personal PM2.5, 1.1 ppb FeNO [95% confidence interval (CI), 0.1-1.9]; for 0.6 microg/m3 personal EC, 0.7 ppb FeNO (95% CI, 0.3-1.1); for 17 ppb personal NO2, 1.6 ppb FeNO (95% CI, 0.4-2.8). Larger associations were found for ambient EC and smaller associations for ambient NO2. Ambient PM2.5 and personal and ambient OC were significant only in subjects taking inhaled corticosteroids (ICS) alone. Subjects taking both ICS and antileukotrienes showed no significant associations. Distributed lag models showed personal PM2.5 in the preceding 5 hr was associated with FeNO. In two-pollutant models, the most robust associations were for personal and ambient EC and NO2, and for personal but not ambient PM2.5. CONCLUSION: PM associations with airway inflammation in asthmatics may be missed using ambient particle mass, which may not sufficiently represent causal pollutant components from fossil fuel combustion.     

Air pollution, airway inflammation, and lung function in a cohort study of Mexico City schoolchildren

BACKGROUND: The biological mechanisms involved in inflammatory response to air pollution are not clearly understood. OBJECTIVE: In this study we assessed the association of short-term air pollutant exposure with inflammatory markers and lung function. METHODS: We studied a cohort of 158 asthmatic and 50 nonasthmatic school-age children, followed an average of 22 weeks. We conducted spirometric tests, measurements of fractional exhaled nitric oxide (Fe(NO)), interleukin-8 (IL-8) in nasal lavage, and pH of exhaled breath condensate every 15 days during follow-up. Data were analyzed using linear mixed-effects models. RESULTS: An increase of 17.5 microg/m(3) in the 8-hr moving average of PM(2.5) levels (interquartile range) was associated with a 1.08-ppb increase in Fe(NO) [95% confidence interval (CI), 1.01-1.16] and a 1.07-pg/mL increase in IL-8 (95% CI 0.98-1.19) in asthmatic children and a 1.16 pg/ml increase in IL-8 (95% CI, 1.00-1.36) in nonasthmatic children. The 5-day accumulated average of exposure to particulate matter <2.5 microm in aerodynamic diamter (PM(2.5)) was significantly inversely associated with forced expiratory volume in 1 sec (FEV(1)) (p=0.048) and forced vital capacity (FVC) (p=0.012) in asthmatic children and with FVC (p=0.021) in nonasthmatic children. Fe(NO) and FEV(1) were inversely associated (p=0.005) in asthmatic children. CONCLUSIONS: Exposure to PM(2.5) resulted in acute airway inflammation and decrease in lung function in both asthmatic and nonasthmatic children.     

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.     

上海市大气污染对不同特征居民呼吸疾病就诊人数影响

  目的  探究黑龙江省牡丹江市大气污染对不同年龄、性别居民呼吸疾病就诊人数影响以及季节性变化,为牡丹江市因大气污染致呼吸疾病的防治提供理论依据。  方法  选择牡丹江市各医院2015年1月 — 2016年12月期间于呼吸科就诊的8 943 515例门诊、急诊就诊人员,采用半参广义相加模型（GAM）分析空气中二氧化硫（SO₂）、可吸入颗粒物（PM_2.5）、二氧化氮（NO₂）等主要大气污染物对不同年龄、性别居民呼吸疾病就诊人数影响。  结果  PM_2.5、NO₂、SO₂作为危险因子,对全人群呼吸系统疾病的最佳滞后天数分别为lag1、lag2、lag0,且污染物每增加增加10 μg/m³对应的ER（95 % CI）分别为3.981%（2.746 ~ 5.216%）、6.938 %（5.017 % ~ 8.859 %）、9.873 %（7.454 % ~12.292 %）;大气污染对女性呼吸系统的影响明显高于男性,儿童和老人更易受大气污染物的影响,其中PM_2.5每升高10 μg/m³,男性儿童（≤ 18岁）、成人（19 ~ 64岁）和老人（≥ 65岁）的呼吸系统就诊例数分别升高 3.308 %（95 % CI = 2.331% ~ 4.285%）、1.667 %（95 % CI = 0.821% ~2.521%）、2.912 %（95 % CI = 2.149 % ~ 3.675 %）,女性分别升高 3.517 %（95 % CI = 2.362 % ~ 4.672 %）、1.839 %（95 % CI = 0.985 % ~ 2.639 %）、3.233 %（95 % CI = 2.459 % ~ 4.007 %）,SO₂、NO₂仅对儿童与老年人群的呼吸系统疾病有影响,对成年人无明显影响。  结论  牡丹江市大气污染对女性呼吸系统的影响显著高于男性,同时对≥ 65岁老人以及≤ 18岁儿童呼吸系统的影响明显高于成年人。     

Long-term exposure to traffic-related air pollution associated with blood pressure and self-reported hypertension in a Danish cohort

Background: Short-term exposure to air pollution has been associated with changes in blood pressure (BP) and emergency department visits for hypertension, but little is known about the effects of long-term exposure to traffic-related air pollution on BP and hypertension.Objectives: We studied whether long-term exposure to air pollution is associated with BP and hypertension.Methods: In 1993–1997, 57,053 participants 50–64 years of age were enrolled in a population-based cohort study. Systolic and diastolic BP (SBP and DBP, respectively) were measured at enrollment. Self-reported incident hypertension during a mean follow-up of 5.3 years was assessed by questionnaire. We used a validated dispersion model to estimate residential long-term nitrogen oxides (NO_x), a marker of traffic-related air pollution, for the 1- and 5-year periods prior to enrollment and before a diagnosis of hypertension. We conducted a cross-sectional analysis of associations between air pollution and BP at enrollment with linear regression, adjusting for traffic noise, measured short-term NO_x, temperature, relative humidity, and potential lifestyle confounders (n = 44,436). We analyzed incident hypertension with Cox regression, adjusting for traffic noise and potential confounders.Results: A doubling of NO_x exposure during 1- and 5-year periods preceding enrollment was associated with 0.53-mmHg decreases [95% confidence interval (CI): –0.88, –0.19 mmHg] and 0.50-mmHg decreases (95% CI: –0.84, –0.16 mmHg) in SBP, respectively. Long-term exposure also was associated with a lower prevalence of baseline self-reported hypertension (per doubling of 5-year mean NO_x: odds ratio = 0.96; 95% CI: 0.91, 1.00), whereas long-term NO_x exposure was not associated with incident self-reported hypertension during follow-up.Conclusions: Long-term exposure to traffic-related air pollution was associated with a slightly lower prevalence of BP at baseline, but was not associated with incident hypertension.     

Altered pulmonary function in children with asthma associated with highway traffic near residence

Cross-sectional analyses were conducted to evaluate the effects of exposure to highway traffic on pulmonary function in Fresno, California. Traffic and spirometry data were available for 214 children (enrollment ages six to 11 years). Multiple linear regression was used to evaluate the relations between pulmonary function and traffic parameters. Heavy-duty vehicle count was used as a surrogate measure for diesel-related exposures. Pulmonary function was non-significantly associated with longer distance-to-road and non-significantly associated with higher traffic intensity. Evaluation of effect modification by FEF_25–75/FVC (a measure of intrinsic airway size) showed that all pulmonary function measures of flow were significantly inversely related to a traffic metric that incorporates traffic intensity and roadway proximity. The results indicate that residence proximity to highway traffic is associated with lower pulmonary function among children with asthma, and smaller airway size is an important modifier of the effect of traffic exposure on pulmonary function and a marker of increased susceptibility.     

Chronic air pollution exposure during pregnancy and maternal and fetal C-reactive protein levels: the Generation R Study

Background: Exposure to air pollution has been associated with higher C-reactive protein (CRP) levels, suggesting an inflammatory response. Not much is known about this association in pregnancy.Objectives: We investigated the associations of air pollution exposure during pregnancy with maternal and fetal CRP levels in a population-based cohort study in the Netherlands.Methods: Particulate matter (PM) with an aerodynamic diameter ≤ 10 μm (PM₁₀) and nitrogen dioxide (NO₂) levels were estimated at the home address using dispersion modeling for different averaging periods preceding the blood sampling (1 week, 2 weeks, 4 weeks, and total pregnancy). High-sensitivity CRP levels were measured in maternal blood samples in early pregnancy (n = 5,067) and in fetal cord blood samples at birth (n = 4,450).Results: Compared with the lowest quartile, higher PM₁₀ exposure levels for the prior 1 and 2 weeks were associated with elevated maternal CRP levels (> 8 mg/L) in the first trimester [fourth PM₁₀ quartile for the prior week: odds ratio (OR), 1.32; 95% confidence interval (CI): 1.08, 1.61; third PM₁₀ quartile for the prior 2 weeks: OR, 1.28; 95% CI: 1.06, 1.56]; however, no clear dose–response relationships were observed. PM₁₀ and NO₂ exposure levels for 1, 2, and 4 weeks preceding delivery were not consistently associated with fetal CRP levels at delivery. Higher long-term PM₁₀ and NO₂ exposure levels (total pregnancy) were associated with elevated fetal CRP levels (> 1 mg/L) at delivery (fourth quartile PM₁₀: OR, 2.18; 95% CI: 1.08, 4.38; fourth quartile NO₂: OR, 3.42; 95% CI: 1.36, 8.58; p-values for trend < 0.05).Conclusions: Our results suggest that exposure to air pollution during pregnancy may lead to maternal and fetal inflammatory responses.