Effect of outdoor and indoor nitrogen dioxide on respiratory symptoms in schoolchildren

BACKGROUND: Nitrogen dioxide (NO(2)), an oxidant gas that contaminates both outdoor and indoor air, is considered to be a potential risk factor for asthma. We investigated concurrently the effects of outdoor and indoor NO(2) on the prevalence and incidence of respiratory symptoms among children. METHODS: A cohort study was carried out over 3 years on 842 schoolchildren living in seven different communities in Japan. Indoor NO(2) concentrations over 24 hours were measured in both winter and summer in the homes of the subjects, and a 3-year average of the outdoor NO(2) concentration was determined for each community. Respiratory symptoms were evaluated every year from responses to questionnaires. RESULTS: The prevalence of bronchitis, wheeze, and asthma significantly increased with increases of indoor NO(2) concentrations among girls, but not among boys. In neither boys nor girls were there significant differences in the prevalence of respiratory symptoms among urban, suburban, and rural districts. The incidence of asthma increased among children living in areas with high concentrations of outdoor NO(2). Multiple logistic regression analysis showed that a 10 parts per billion (ppb) increase of outdoor NO(2) concentration was associated with an increased incidence of wheeze and asthma (odds ratios [OR] = 1.76, 95% CI : 1.04-3.23 and OR = 2.10, 95% CI : 1.10-4.75, respectively), but that no such associations were found with indoor NO(2) concentration (OR = 0.73, 95% CI : 0.45-1.14 and OR = 0.87, 95% CI : 0.51-1.43, respectively). CONCLUSIONS: These findings suggest that outdoor NO(2) air pollution may be particularly important for the development of wheeze and asthma among children. Indoor NO(2) concentrations were associated with the prevalence of respiratory symptoms only among girls. Girls may be more susceptible to indoor air pollution than boys.     

Air Pollution and Respiratory Status in Asthmatic Children: Hints for a Locally Based Preventive Strategy. AIRE Study

Respiratory health effects of short-term exposure to ambient air pollution have been examined in 120 'asthma-like' school-aged children in some areas of Emilia-Romagna (urban-industrial and rural area). They kept a daily diary, through 12 weeks, for respiratory symptoms, PEF measurements, drug consumption and daily activity. The average daily concentrations of air pollutants in the same period (TSP, NO2, CO, PM2.5) were higher in the industrial than the rural area. Asthma was diagnosed in 77% of cases, 85% of subjects took medical treatments for respiratory disease in the last year and 90% used medicine for respiratory diseases. Significantly lower variations in PEF, between morning and evening, were observed in the rural area, considering only the asthmatic or cough subsets of children. Symptom prevalence was higher in the urban-industrial area than the rural area; the most frequent symptoms were cough, phlegm and stuffed nose. The two area populations are homogeneous in individual features, family susceptibility, passive smoking exposure and atopy. The differences observed in the frequency of daily reported symptoms could be attributed to external situations like the different reported exposures to pollutants. Although most analyses revealed non-significant associations, panel analysis showed a significant statistical risk for the cough and phlegm group by an increase of 10 microg of TSP (RR 1.0017, 95% CI: 1.0002-1.0033) in the entire group. In the urban-industrial panel we observed a significant association between cough and phlegm together and PM2.5 (RR 1.0044, 95% CI: 1.0011-1.0077). The results of this investigation should be used in orienting local political decisions.     

Acute effects of the breathing of industrial waste and of sulfur dioxide on the respiratory health of children living in the industrial area of Puchuncaví, Chile]

This study investigated the acute effect of air pollution on the respiratory health of children living in the industrial area of Puchuncaví, in Region V of Chile. The 114 children studied were from 6 to 12 years old; 57 of them had chronic respiratory symptoms and 57 did not. Each day for 66 days the air was checked for levels of sulfur dioxide (SO2) and of breathable particles that were < 10 microns (PM10). The children were selected and classified according to their susceptibility to chronic respiratory disease by means of a questionnaire used with 882 children living within the area of the emissions from a copper foundry and a thermoelectric plant. Each day, each studied child's peak expiratory flow (PEF) and incidence of respiratory symptoms were checked and recorded. Using regression models (generalized estimation equations), estimates were made of the association of SO2 and PM10 levels with PEF and the incidence of cough, expectoration, episodes of wheezing, dyspnea, and use of bronchodilators. Among the children who were initially symptomatic, an increase of 50 micrograms/m3 in the daily mean level of SO2 caused a reduction of -1.42 L/min (95% confidence interval (95% CI): -2.84 to -0.71) in the PEF of the following day. An increase of 30 micrograms/m3 in the cumulative concentration of PM10 over three days produced a PEF reduction of -2.84 L/min (95% CI: -4.26 to 0.00). With respect to symptoms, an increase of 30 micrograms/m3 in the weekly mean level of PM10 was related with a 26% increase (odds ratio (OR) = 1.26; 95% CI: 1.01 to 1.57) in the incidence of cough and of 23% (OR = 1.23; 95% CI: 1.00 to 1.50) in the incidence of expectoration. An increase of 50 micrograms/m3 in the mean level of SO2 for three days was associated with a 5% increase (OR = 1.05; 95% CI: 1.00 to 1.10) in the incidence of expectoration. An increase of 30 micrograms/m3 in the daily average of PM10 increased the use of bronchodilators two days later by 10% (OR = 1.10; 95% CI: 1.03 to 1.18). Among the initially asymptomatic children, a significant effect from PM10 exposure was found after an increase of 30 micrograms/m3 in the mean daily PM10 level, with a reduction of -1.34 L/min (95% CI: -2.68 to -0.67) in the PEF of the following day. A similar increase in the cumulative exposure over three days was associated with an increase of 9% in the incidence of episodes of wheezing (OR = 1.09; 95% CI: 1.01 to 1.31). It is concluded that high levels of PM10 and SO2 affect the respiratory health of children living in the industrial area of Puchuncaví.     

Effects of fine and ultrafine particles on cardiorespiratory symptoms in elderly subjects with coronary heart disease: the ULTRA study

The ULTRA Study, a study investigating the association between fine and ultrafine particulate air pollution and cardiorespiratory health, was conducted during the winter of 1998-1999 in Amsterdam, the Netherlands; Erfurt, Germany; and Helsinki, Finland. At each study center, a panel of elderly subjects with coronary heart disease recorded cardiac and respiratory symptoms in a diary. Exposure to ambient air pollution was characterized by measuring daily mass concentrations of particles smaller than 10 micro m (PM(10)) and 2.5 micro m (PM(2.5)), number concentrations of ultrafine particles (NC(0.01-0.1)), and gases. Odds ratios for the relation of symptoms to air pollution, adjusted for time trend, respiratory infections, and meteorologic variables, were mostly homogeneous across the centers. No association was found between air pollution and chest pain. A 10- micro g/m(3) increase in PM(2.5) was positively associated with the incidence of shortness of breath (odds ratio (OR) = 1.12, 95% confidence interval (CI): 1.02, 1.24) and with avoidance of activities (OR = 1.09, 95% CI: 0.97, 1.22). NC(0.01-0.1) was only associated with the prevalence of avoidance of activities (OR = 1.10, 95% CI: 1.01, 1.19). In conclusion, PM(2.5) was associated with some cardiac symptoms in three panels of elderly subjects. PM(2.5 )was more strongly related to cardiorespiratory symptoms than ultrafine particles were.     

A comparison of particulate matter from biomass-burning rural and non-biomass-burning urban households in northeastern China

BACKGROUND: Biomass fuel is the primary source of domestic fuel in much of rural China. Previous studies have not characterized particle exposure through time-activity diaries or personal monitoring in mainland China. OBJECTIVES: In this study we characterized indoor and personal particle exposure in six households in northeastern China (three urban, three rural) and explored differences by location, cooking status, activity, and fuel type. Rural homes used biomass. Urban homes used a combination of electricity and natural gas. METHODS: Stationary monitors measured hourly indoor particulate matter (PM) with an aerodynamic diameter < or = 10 microm (PM10) for rural and urban kitchens, urban sitting rooms, and outdoors. Personal monitors for PM with an aerodynamic diameter < or = 2.5 microm (PM2.5) were employed for 10 participants. Time-activity patterns in 30-min intervals were recorded by researchers for each participant. RESULTS: Stationary monitoring results indicate that rural kitchen PM10 levels are three times higher than those in urban kitchens during cooking. PM10 was 6.1 times higher during cooking periods than during noncooking periods for rural kitchens. Personal PM2.5 levels for rural cooks were 2.8-3.6 times higher than for all other participant categories. The highest PM2.5 exposures occurred during cooking periods for urban and rural cooks. However, rural cooks had 5.4 times higher PM2.5 levels during cooking than did urban cooks. Rural cooks spent 2.5 times more hours per day cooking than did their urban counterparts. CONCLUSIONS: These findings indicate that biomass burning for cooking contributes substantially to indoor particulate levels and that this exposure is particularly elevated for cooks. Second-by-second personal PM2.5 exposures revealed differences in exposures by population group and strong temporal heterogeneity that would be obscured by aggregate metrics.     

Decline of ambient air pollution levels and improved respiratory health in Swiss children

The causality of observed associations between air pollution and respiratory health in children is still subject to debate. If reduced air pollution exposure resulted in improved respiratory health of children, this would argue in favor of a causal relation. We investigated whether a rather moderate decline of air pollution levels in the 1990s in Switzerland was associated with a reduction in respiratory symptoms and diseases in school children. In nine Swiss communities, 9,591 children participated in cross-sectional health assessments between 1992 and 2001. Their parents completed identical questionnaires on health status and covariates. We assigned to each child an estimate of regional particles with an aerodynamic diameter < 10 microg/m3 (PM10) and determined change in PM10 since the first survey. Adjusted for socioeconomic, health-related, and indoor factors, declining PM10 was associated in logistic regression models with declining prevalence of chronic cough [odds ratio (OR) per 10-microg/m3 decline = 0.65, 95% confidence interval (CI), 0.54-0.79], bronchitis (OR = 0.66; 95% CI, 0.55-0.80), common cold (OR = 0.78; 95% CI, 0.68-0.89), nocturnal dry cough (OR = 0.70; 95% CI, 0.60-0.83), and conjunctivitis symptoms (OR = 0.81; 95% CI, 0.70-0.95). Changes in prevalence of sneezing during pollen season, asthma, and hay fever were not associated with the PM10 reduction. Our findings show that the reduction of air pollution exposures contributes to improved respiratory health in children. No threshold of adverse effects of PM10 was apparent because we observed the beneficial effects for relatively small changes of rather moderate air pollution levels. Current air pollution levels in Switzerland still exceed limit values of the Swiss Clean Air Act; thus, children's health can be improved further.     

Air pollution and exacerbation of asthma in African-American children in Los Angeles

Significant increases in asthma morbidity and mortality in the United States have occurred since the 1970s, particularly among African-Americans. Exposure to various environmental factors, including air pollutants and allergens, has been suggested as a partial explanation of these trends. To examine relations between several air pollutants and asthma exacerbation in African-Americans, we recruited a panel of 138 children in central Los Angeles. We recorded daily data on respiratory symptoms and medication use for 13 weeks and examined these data in conjunction with data on ozone (O3) nitrogen dioxide (NO2), particulate matter (PM10 and PM2.5), meteorological variables, pollens, and molds. Using generalized estimating equations, we found associations between respiratory symptom occurrence and several environmental factors. For example, new episodes of cough were associated with exposure to PM10 (OR = 1.25; 95% CI = 1.12-1.39; interquartile range [IQR] = 17 microg/m3, 24-hour average), PM2.5 (OR = 1.10; 95% CI = 1.03-1.18; IQR = 30 microg/m3, 12-hour average), NO2, and the molds Cladosporium and Alternaria, but not with exposure to O3 or pollen. The factors PM10 and O3 were associated with the use of extra asthma medication. For this population several bioaerosols and air pollutants had effects that may be clinically significant.     

深圳市罗湖区35户住宅室内环境检测结果分析

目的 了解城市室内环境状况,发现室内环境健康危害因素。方法 分别于2018年夏季和2019年冬季对35户住宅进行室内危害因素检测,采样方法、布点原则及评价参照《室内空气质量标准》（GB/T 18883 - 2002）进行。结果 室内PM10、CO、CO2、NO2、甲醛、苯、甲苯、二甲苯浓度均在标准限值内,配对资料的t检验分析显示冬夏两季室内PM2.5、PM10、CO2、NO2、甲醛浓度差异有统计学意义（PM2.5:t = - 7.151,PM10:t = - 6.693, CO2:t = -3.970,NO2:t = - 4.479,甲醛 t = 2.953, P＜0.05）,其中冬季室内PM2.5、PM10、CO2、NO2总体浓度高于夏季,夏季室内甲醛浓度高于冬季。Pearson相关分析显示室内空气中真菌总数与湿度存在正相关关系（r = 0.244,P＜0.05）,真菌总数与PM2.5呈负相关关系（r = - 0.183,P＜0.05）。结论 深圳市城区室内PM10、CO、CO2、NO2、甲醛、苯、甲苯、二甲苯浓度均在标准限值内,仍需进一步关注室内微生物因素对健康的危害。     

广州市某农村地区家庭室内生物燃料使用与居民下呼吸道症状关系的研究

目的了解广州市某农村地区家庭室内生物燃料使用对居民下呼吸道症状的影响。方法采用系统抽样方法在广州增城市某农村地区抽取6岁以上的常住居民作为研究对象,开展问卷调查获取室内生物燃料使用和居民下呼吸道症状的情况。采用多因素非条件logistic回归分析居民呼吸道症状与生物燃料使用的关系,分析中控制年龄、性别、吸烟情况、室内通风情况和厨房使用通风设备情况等因素。结果共调查了266户家庭,645名研究对象纳入研究,其中478人（74．1％）做饭使用生物燃料,167人（25．9％）做饭使用清洁能源。生物燃料组过去半年下呼吸道症状（含干咳、咳痰、气喘、胸闷和呼吸困难症状之一）发生率为51．5％（246／478）,清洁能源组发生率为41．3％（69／167）。多因素分析显示,使用生物燃料组发生过咳痰（OR=1．90,95％CI：1．23～2．93）、气喘（OR=6．71,95％ CI：1．74～25．85）、胸闷（OR=2．41,95％CI：1．02—5．72）和呼吸困难（OR=5．99,95％CI：1．23～29．28）的风险高于清洁能源组。下呼吸道症状发生风险与生物燃料使用的频率关系有统计学意义,每天都使用生物燃料组相比清洁能源组,出现过和经常出现下呼吸道症状的风险分别是OR=1．72（95％CI：1．14～2．59）和OR=4．10（95％CI：1．40-12．04）。结论广州市农村地区室内生物燃料的使用可能影响居民呼吸系统健康。     

Traffic air pollution and other risk factors for respiratory illness in schoolchildren in the niger-delta region of Nigeria

Background: Association of childhood respiratory illness with traffic air pollution has been investigated largely in developed but not in developing countries, where pollution levels are often very high.Objectives: In this study we investigated associations between respiratory health and outdoor and indoor air pollution in schoolchildren 7–14 years of age in low socioeconomic status areas in the Niger Delta.Methods: A cross-sectional survey was carried out among 1,397 schoolchildren. Exposure to home outdoor and indoor air pollution was assessed by self-report questionnaire. School air pollution exposures were assessed using traffic counts, distance of schools to major streets, and particulate matter and carbon monoxide measurements, combined using principal components analysis. Hierarchical logistic regression was used to examine associations with reported respiratory health, adjusting for potential confounders.Results: Traffic disturbance at home (i.e., traffic noise and/or fumes evident inside the home vs. none) was associated with wheeze [odds ratio (OR) = 2.16; 95% confidence interval (CI), 1.28–3.64], night cough (OR = 1.37; 95% CI, 1.03–1.82), phlegm (OR = 1.49; 95% CI, 1.09–2.04), and nose symptoms (OR = 1.40; 95% CI, 1.03–1.90), whereas school exposure to a component variable indicating exposure to fine particles was associated with increased phlegm (OR = 1.38; 95% CI, 1.09–1.75). Nonsignificant positive associations were found between cooking with wood/coal (OR = 2.99; 95% CI, 0.88–10.18) or kerosene (OR = 2.83; 95% CI, 0.85–9.44) and phlegm compared with cooking with gas.Conclusion: Traffic pollution is associated with respiratory symptoms in schoolchildren in a deprived area of western Africa. Associations may have been underestimated because of nondifferential misclassification resulting from limitations in exposure measurement.     

2018-2019年六安市宾馆室内空气卫生状况及影响因素分析

目的了解六安市部分宾馆室内空气卫生现状,分析室内工作场所环境对呼吸系统的影响,为加强公共场所卫生管理提供科学依据。方法于2018-2019年对六安市部分公共场所进行卫生监测和评价,并通过从业人员健康危因素问卷分析呼吸系统感觉或症状与工作场所环境的关系。使用Excel 2010软件整理数据,利用SPSS 21.0分析数据,率的比较采用卡方检验,检验水准α=0.05。结果2018-2019年共检测163个酒店房间,检测项目合计1467项次。在各项检测指标中合格率前两位分别是CO2体积分数和甲醛,湿度和PM2.5合格率较低,分别为34.97%和38.04%。2019年相比2018年温度合格率上升,湿度和PM10合格率下降,差异有统计学意义(P<0.05)。不同轮次的温度、湿度、甲醛、PM2.5、细菌总数、PM10、CO2差异有统计学意义(P<0.05)。不同星级的宾馆温度、PM10差异有统计学意义(P<0.05)。细菌总数与湿度呈正相关,真菌总数与温度呈负相关。PM2.5、PM10质量浓度与温度及湿度呈负相关。甲醛与温度呈正相关。室内PM10、PM2.5与室外PM10、PM2.5呈正相关。宾馆冷却塔嗜肺军团菌2018年合格率为100%,2019年合格率为25%。宾馆从业人员呼吸系统感觉或症状的环境危害因素为空气干燥(OR=2.424,95%CI:1.257~4.677)、有刺激性气味(OR=4.708,95%CI:1.673~13.251)、有霉味(OR=2.210,95%CI:1.002~4.876)和空气中有灰尘(OR=1.926,95%CI:1.035~3.586)。结论夏季甲醛浓度因受温度和湿度影响其合格率比冬季低。冬季室内颗粒物浓度因受室外空气质量影响,比夏季高。三星级及以上宾馆温度的合格率较高,快捷宾馆PM10合格率较高。在室外空气质量好的情况下,应加强开窗通风或机械通风,并应完善室内空气和空调系统消毒制度,从而改善室内微小气侯,并应加强室内空气有害物质监测和治理。     

Association between maternal exposure to ambient air pollutants during pregnancy and fetal growth restriction

Previous research demonstrated consistent associations between ambient air pollution and emergency room visits, hospitalizations, and mortality. Effect of air pollution on perinatal outcomes has recently drawn more attention. We examined the association between intrauterine growth restriction (IUGR) among singleton term live births and sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particles (PM2.5) present in ambient air in the Canadian cities of Calgary, Edmonton, and Montreal for the period 1985-2000. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for IUGR, based on average daily levels of individual pollutants over each month and trimester of pregnancy after adjustment for maternal age, parity, infant gender, season, and city of residence. A 1 ppm increase in CO was associated with an increased risk of IUGR in the first (OR=1.18; 95% CI 1.14-1.23), second (OR=1.15; 95% CI 1.10-1.19) and third (OR=1.19; 95% CI 1.14-1.24) trimesters of pregnancy, respectively. A 20 ppb increase in NO2 (OR=1.16; 95% CI 1.09-1.24; OR=1.14; 95% CI 1.06--1.21; and OR=1.16; 95% CI 1.09-1.24 in the first, second, and third trimesters) and a 10 mug/m3 increase in PM2.5 (OR=1.07; 95% CI 1.03-1.10; OR=1.06; 95% CI 1.03-1.10; and OR=1.06; 95% CI 1.03-1.10) were also associated with an increased risk of IUGR. Consistent results were found when ORs were calculated by month rather than trimester of pregnancy. Our findings add to the emerging body of evidence that exposure to relatively low levels of ambient air pollutants in urban areas during pregnancy is associated with adverse effects on fetal growth.     

Indoor environment and respiratory symptoms in children living in the Dutch-German borderland

OBJECTIVE: To investigate the relation between indoor environmental risk factors and respiratory symptoms in 7-8-year-old children living in the Dutch-German borderland. METHODS: A nested case-control study was conducted among children participating in a large longitudinal study on respiratory health. Parents of all 781 children with respiratory complaints and an equal number of randomly selected controls were asked to complete a questionnaire, including questions on indoor environment. RESULTS: The parents of 1191 children (76.2%) participated. Past exposure to environmental (OR = 2.73, 95% CI 1.14-6.67) as well as in utero exposure (OR = 2.28, 95% CI 1.15-4.53) to tobacco smoke, use of an unvented geyser for water heating (OR = 3.01, 95% CI 1.21-7.56), long-term exposure to dampness (OR = 2.98, 95% CI 1.10-8.28) or pets (OR = 2.18, 95% CI 1.39-3.42) increased the risk of asthmatic symptoms in 7-8-year-old children. A middle or low socio-economic status also increased the risk of asthmatic symptoms. An inverse association with asthmatic symptoms was seen for wall-to-wall carpeting (OR = 0.57, 95% CI 0.33-0.95) and insulation measures (OR = 0.46, 95% CI 0.25-0.83). Except for the presence of an unvented geyser, these environmental risk factors also presented a risk for coughing symptoms in children. CONCLUSION: This study showed an increased risk of respiratory symptoms in children exposed to several indoor environmental risk factors.     

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 < or = 10 microm (PM10) (odds ratio (OR) = 2.91; 95% confidence interval (CI) = 1.46-5.80), but was not associated with community levels of ozone, nitrogen dioxide, PM2.5 (diameter < or = 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%CI = 1.19-2.70]; OR = 1.80 [95%CI = 1.23-2.65]; OR = 1.57 [95% CI = 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%CI = 1.61-5.86]; OR = 1.31 [95%CI = 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.     

Indoor allergens, asthma, and asthma-related symptoms among adolescents in Wuhan, China

PURPOSE: Information on indoor allergen exposures among non-Western populations, which have lower prevalence of atopic illness, is scant. We examined whether exposures to common indoor allergens were associated with doctor-diagnosed asthma and asthma-related symptoms among Chinese adolescents. METHODS: A cross-sectional study of 4,185 ninth grade students was conducted at 22 randomly selected schools in Wuhan, China. Information on respiratory health and exposures to indoor allergens was obtained by a self-administered questionnaire completed in class. RESULTS: Having animals currently was associated with persistent cough [prevalence odds ratio (POR)=1.54, 95% confidence interval (CI ): 1.21-2.11] and wheeze (POR=1.41, 95% CI: 1.03-1.94). Early-life exposure to animals was also associated with doctor-diagnosed asthma (POR=1.95, 95% CI: 1.35-2.82). Associations with respiratory symptoms strengthened with higher levels of exposure and for exposure in both early childhood and in adolescence. Exposure to cockroaches and having mold/water damage in the home contributed especially to wheezing (POR=2.03, 95% CI: 1.41-2.90 for cockroaches; POR=2.49, 95% CI: 1.82-3.40 for mold/water damage). CONCLUSIONS: Indoor allergen exposures were positively associated with asthma diagnosis and persistent respiratory symptoms among Chinese adolescents. Neither early-life nor current exposure to animals was protective for asthma or asthma-related symptoms.     

Vapor, dust, and smoke exposure in relation to adult-onset asthma and chronic respiratory symptoms: the Singapore Chinese Health Study

Occupational factors contribute to a significant fraction of respiratory disease and symptoms. The authors evaluated the role of occupational exposures in asthma, chronic bronchitis, and respiratory symptoms in the Singapore Chinese Health Study, a population-based cohort of adults aged 45-74 years at enrollment in 1993-1998. Information on occupations and occupational exposures was collected at enrollment for 52,325 subjects for whom respiratory outcomes were obtained via follow-up interviews in 1999-2004. Exposure to dusts from cotton, wood, metal, minerals, and/or asbestos was associated with nonchronic cough and/or phlegm (odds ratio (OR) = 1.19, 95% confidence interval (CI): 1.08, 1.30), chronic bronchitis (OR = 1.26, 95% CI: 1.01, 1.57), and adult-onset asthma (OR = 1.14, 95% CI: 1.00, 1.30). Cotton dust was the major contributor to respiratory symptoms. Vapor exposure from chemical solvents, dyes, cooling oils, paints, wood preservatives, and/or pesticides was associated with nonchronic cough or phlegm (OR = 1.14, 95% CI: 1.03, 1.27), chronic dry cough (OR = 1.55, 95% CI: 1.19, 2.01), and adult-onset asthma (OR = 1.34, 95% CI: 1.15, 1.56). Chemical solvents, cooling oils, and pesticides were the major contributors to respiratory symptoms. These data support the role of occupational exposures in the etiology of respiratory illness in a population-based cohort in Singapore with a low prevalence of atopic illness.     

Exhaled nitric oxide in children with asthma and short-term PM2.5 exposure in Seattle

The objective of this study was to evaluate associations between short-term (hourly) exposures to particulate matter with aerodynamic diameters < 2.5 microm (PM2.5) and the fractional concentration of nitric oxide in exhaled breath (FE(NO) in children with asthma participating in an intensive panel study in Seattle, Washington. The exposure data were collected with tapered element oscillation microbalance (TEOM) PM2.5 monitors operated by the local air agency at three sites in the Seattle area. FE(NO) is a marker of airway inflammation and is elevated in individuals with asthma. Previously, we reported that offline measurements of FE(NO) are associated with 24-hr average PM2.5 in a panel of 19 children with asthma in Seattle. In the present study using the same children, we used a polynomial distributed lag model to assess the association between hourly lags in PM2.5 exposure and FE(NO) levels. Our model controlled for age, ambient NO levels, temperature, relative humidity, and modification by use of inhaled corticosteroids. We found that FE(NO) was associated with hourly averages of PM2.5 up to 10-12 hr after exposure. The sum of the coefficients for the lag times associated with PM2.5 in the distributed lag model was 7.0 ppm FE(NO). The single-lag-model FE(NO) effect was 6.9 [95% confidence interval (CI), 3.4 to 10.6 ppb] for a 1-hr lag, 6.3 (95% CI, 2.6 to 9.9 ppb ) for a 4-hr lag, and 0.5 (95% CI, -1.1 to 2.1 ppb) for an 8-hr lag. These data provide new information concerning the lag structure between PM2.5 exposure and a respiratory health outcome in children with asthma.     

Respiratory symptoms and peak expiratory flow in children with asthma in relation to volatile organic compounds in exhaled breath and ambient air

Indoor volatile organic compounds (VOCs) have been associated with asthma, but there is little epidemiologic work on ambient exposures, and no data on relationships between respiratory health and exhaled breath VOCs, which is a biomarker of VOC exposure. We recruited 26 Hispanic children with mild asthma in a Los Angeles community with high VOC levels near major freeways and trucking routes. Two dropped out, three had invalid peak expiratory flow (PEF) or breath VOC data, leaving 21. Children filled out symptom diaries and performed PEF maneuvers daily, November 1999-January 2000. We aimed to collect breath VOC samples on asthma episode and baseline symptom-free days, but six subjects only gave samples on symptom-free days. We analyzed 106 breath samples by GC-MS. Eight VOCs were quantifiable in >75% of breath samples (benzene, methylene chloride, styrene, tetrachloroethylene, toluene, m,p-xylene, o-xylene, and p-dichlorobenzene). Generalized estimating equation and mixed linear regression models for VOC exposure-response relationships controlled for temperature and respiratory infections. We found marginally positive associations between bothersome or more severe asthma symptoms and same day breath concentrations of benzene [odds ratio (OR) 2.03, 95% confidence interval (CI) 0.80, 5.11] but not other breath VOCs. Ambient petroleum-related VOCs measured on the same person-days as breath VOCs showed notably stronger associations with symptoms, including toluene, m,p-xylene, o-xylene, and benzene (OR 5.93, 95% CI 1.64, 21.4). On breath sample days, symptoms were also associated with 1-h ambient NO(2), OR 8.13 (1.52, 43.4), and SO(2), OR 2.36 (1.16, 4.81). Consistent inverse relationships were found between evening PEF and the same ambient VOCs, NO(2), and SO(2). There were no associations with O(3). Given the high traffic density of the region, stronger associations for ambient than for breath VOCs suggest that ambient VOC measurements were better markers for daily exposure to combustion-related compounds thought to be causally related to acute asthma. Alternatively, the low sample size of symptom responses (15-21 responses per 108 breath samples) may have led to the nonsignificant results for breath VOCs.     

Acute effects of urban air pollution on respiratory health of children with and without chronic respiratory symptoms

OBJECTIVES: To investigate to what extent different components of air pollution are associated with acute respiratory health effects in children with and without chronic respiratory symptoms. METHODS: During three consecutive winters starting in 1992-3, peak expiratory flow (PEF) and respiratory symptoms were registered daily in panels of children of 7-11 years old with and without symptoms, living in urban areas with high traffic intensity in The Netherlands. Simultaneously, panels of children living in non-urban areas were studied. Daily measurements of particles with aerodynamic diameter < 10 microns (PM10), black smoke (BS), sulphate, SO2, and NO2 were performed in both areas. RESULTS: The contrast in particle concentrations (PM10, BS, and sulphate) between urban and non-urban areas was small, but there was more contrast in the concentrations of SO2 and NO2. In children with symptoms from both areas, significant associations were found between PM10, BS, and sulphate concentrations and the prevalence of symptoms of the lower respiratory tract (LRS) and decrements in PEF. Particle concentrations were also associated with use of bronchodilators in the urban areas, but not in the non-urban areas. After stratification by use of medication, stronger associations were found in children who used medication than in children who did not use medication. The magnitude of the estimated effects was in the order of a twofold increase in the use of bronchodilators, a 50% increase in LRS, and an 80% increase in decrements in PEF for a 100 micrograms/m3 increase in the 5 day mean PM10 concentration. In children without symptoms, significant associations were found between concentrations of PM10 and BS and decrements in PEF in both areas, but these associations were smaller than those for children with symptoms. No associations with respiratory symptoms were found. CONCLUSIONS: The results suggest that children with symptoms are more susceptible to the effects of particulate air pollution than children without symptoms, and that use of medication for asthma does not prevent the adverse effects of particulate air pollution in children with symptoms.

 

     

A cohort study of indoor nitrogen dioxide and house dust mite exposure in asthmatic children

OBJECTIVE: The purpose of this study was to investigate dose-response relationships between asthma symptoms and indoor nitrogen dioxide (NO2) and house dust mite allergen (HDM) in children. METHODS: Asthmatic children from 18 primary schools in Adelaide, Australia, kept a daily symptoms diary over 12 weeks. Home and classroom NO2 levels were measured repeatedly in winter 2000. HDM levels were obtained from beds. Lung function tests were performed at the beginning and at the end of the study period. RESULTS: Data on exposure and respiratory outcomes were gathered for 174 children. For school exposure, the estimated relative symptom rate (RR) for a 10-ppb increase in NO2 for difficulty breathing during the day was 1.09 (95% confidence interval [CI] = 1.03-1.15), at night 1.11 (95% CI = 1.05-1.18), and for chest tightness at night 1.12 (95% CI = 1.07-1.17). Significant symptom rate increases were also found for kitchen NO2 exposure. This was supported by a negative dose-response relationship between percentage predicted forced expiratory volume in 1 second and NO2 (-0.39%; 95% CI = -0.76 to -0.02) for kitchen exposure. Significant threshold effects using a 10-microg/g cutoff point for HDM exposure were established in the sensitized children for nighttime wheeze (RR = 3.62, 95% CI = 1.49-8.77), daytime cough (RR = 1.64, 95% CI = 1.14-2.36), and daytime asthma attack (RR = 1.95, 95% CI = 1.06-3.60). CONCLUSION: This study has established reliable risk estimates for exacerbations of asthma symptoms in children based on dose-response investigations of indoor NO2 and HDM.