Increase In NO2 Exposure Research Articles

Air pollution exposure in association with maternal thyroid function during early pregnancy.

Association of prenatal air pollution exposure with maternal thyroid hormone (TH) levels remains unclear, especially during early pregnancy when even small changes in maternal TH could affect fetal neurodevelopment. We examined the effect of air pollution exposure on maternal TH levels in the second trimester of pregnancy. Serum concentrations of free thyroxine (FT4) and thyroid-stimulating hormone (TSH) in 8077 pregnant women were measured by fluorescence and chemiluminescence immunoassays. Prenatal exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) was estimated using land use regression models. FT4 levels were significantly inversely associated with both PM2.5 and NO2 exposure. A 10 μg/m3 increase in NO2 exposure in first trimester and PM2.5 exposure in second trimester was associated with 0.61% (95% CI, -0.88% to -0.35%) and 0.73% (95% CI, -1.25% to -0.20%) decrease in FT4 levels, respectively. PM2.5 exposure was also associated with elevated odds of maternal hypothyroxinemia. A 10 μg/m3 increase in PM2.5 exposure in both first and second trimester was associated with 28% (OR = 1.28, 95% CI, 1.05-1.57) and 23% (OR = 1.23, 95% CI, 1.00-1.51) increase in the odds of maternal hypothyroxinemia, respectively. Our findings suggest that air pollution may interfere with maternal thyroid function during early pregnancy.

The Association of Ambient Air Pollution with Sleep Apnea: The Multi-Ethnic Study of Atherosclerosis.

Air pollution may influence sleep through airway inflammation or autonomic nervous system pathway alterations. Epidemiological studies may provide evidence of relationships between chronic air pollution exposure and sleep apnea. To determine whether ambient-derived pollution exposure is associated with obstructive sleep apnea and objective sleep disruption. We analyzed data from a sample of participants in MESA (Multi-Ethnic Study of Atherosclerosis) who participated in both the Sleep and Air studies. Mean annual and 5-year exposure levels to nitrogen dioxide (NO2) and particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) were estimated at participants' homes using spatiotemporal models based on cohort-specific monitoring. Participants completed in-home full polysomnography and 7 days of wrist actigraphy. We used multivariate models, adjusted for demographics, comorbidities, socioeconomic factors, and site, to assess whether air pollution was associated with sleep apnea (apnea-hypopnea index ≥ 15) and actigraphy-measured sleep efficiency. The participants (n = 1,974) were an average age of 68 (±9) years, 46% male, 36% white, 24% Hispanic, 28% black, and 12% Asian; 48% had sleep apnea and 25% had a sleep efficiency of ≤88%. A 10 ppb annual increase in NO2 exposure was associated with 39% greater adjusted odds of sleep apnea (95% confidence interval [CI], 1.03-1.87). A 5 μg/m3 greater annual PM2.5 exposure was also associated with 60% greater odds of sleep apnea (95% CI, 0.98-2.62). Sleep efficiency was not associated with air pollution levels in fully adjusted models. Individuals with higher annual NO2 and PM2.5 exposure levels had a greater odds of sleep apnea. These data suggest that in addition to individual risk factors, environmental factors also contribute to the variation of sleep disorders across groups, possibly contributing to health disparities.

Exposure to Air Pollutants and Variation of Blood Glucose Level among Gestational Diabetes Mellitus in China: A Retrospective Cohort Study

Background: Air pollution has been reported to be associated with risk of type 2 diabetes, but few studies were available for the associations with blood glucose level in pregnant women.Objectives: We aimed to examine the effects of exposure to air pollution on blood glucose in GDM patients in a retrospective cohort study.Methods: We identified GDM cases from hospital records among 35,722 women who were pregnant from January 2013 to May 2017.We used generalized additional models to estimate adverse effects of air pollution on fasting blood glucose and OGTT among GDM patients.Results: We identified a total of 1,347 women with GDM. An IQR increase in NO2 exposure during the second trimester was associated with an increment of fasting blood glucose (FBG) level by 0.42mmol/L. Significant associations were observed among women with younger age (β=0.55, p<0.05 for CO), overweight/obesity (β=0.52, p<0.05 for NO2, β=0.70, p<0.05 for CO), lower education (β=1.08, p<0.05 for NO2，β=0.83 for CO), and among manual labor(β=1.12, p<0.05 for NO2) and housewife(β=1.46, p<0.05 for CO). Our estimates for air pollutants (NO2 and CO) and OGTT were generally consistent with the corresponding β values for FBG. No evidence was observed for the association between particle matter, SO2 and Particle Matter exposure and FBG/OGTT level in our study.Conclusions: In the present study, women were at increased risk for higher blood glucose level when exposure to higher residential NO2 and CO during their pregnancy. Women with higher BMI, lower education level were more susceptible to the adverse effects of ambient air pollution.

Exposure to nitrogen dioxide and chronic obstructive pulmonary disease (COPD) in adults: a systematic review and meta-analysis.

Exposure to nitrogen dioxide (NO2) has long been linked to elevated mortality and morbidity from epidemiological evidences. However, questions remain unclear whether NO2 acts directly on human health or being an indicator of other ambient pollutants. In this study, random-effect meta-analyses were performed on examining exposure to nitrogen oxide (NOx) and its association with chronic obstructive pulmonary disease (COPD). The overall relative risk (RR) of COPD risk related to a 10μg/m3 increase in NO2 exposure increased by 2.0%. The pooled effect on prevalence was 17% with an increase of 10μg/m3 in NO2 concentration, and 1.3% on hospital admissions, and 2.6% on mortality. The RR of COPD cases related to NO2 long-term exposure was 2.5 and 1.4% in short-term exposure. The COPD effect related with a 10μg/m3 increase in exposure to a general outdoor-sourced NO2 was 1.7 and 17.8% to exposure to an exclusively traffic-sourced NO2; importantly, we did observe the effect of NO2 on COPD mortality with a large majority in lag0. Long-term traffic exerted more severe impairments on COPD prevalence than long-term or short-term outdoor effect; long-term mortality effect on COPD was serious in single model from this meta-analysis. Overall, our study reported consistent evidence of the potential positive association between NO2 and COPD risk.

Air Pollution and Performance-Based Physical Functioning in Dutch Older Adults

Background/Aim: Functional limitations are a major cause for needing care and institutionalization among older adults. It has been suggested that exposure to air pollution is associated with increased functional limitations in older people. We assessed the association between air pollution and physical functioning in Dutch older adults. Methods: We analyzed data on performance-based and self-reported physical functioning for 1,735 participants of the Longitudinal Aging Study Amsterdam, who participated in at least one of three measurement cycles performed in 2005/2006, 2008/2009 and 2011/2012. Annual average outdoor air pollution concentrations [nitrogen dioxide (NO2), nitrogen oxides (NOx), particulate matter with diameters ≤ 2.5 µm (PM2.5), ≤ 10 µm (PM10), and 2.5-10 µm (PMcoarse), and PM2.5 absorbance] at the home address at the start of the first measurement cycle were estimated using land-use regression models. Analyses were performed using mixed models with random subject intercept accounting for correlation between repeated measurements within subjects, and adjusting for potential confounders. Results: Exposure to most air pollutants was associated with reduced performance-based physical functioning, e.g. an inter-quartile range increase in NO2 exposure was associated with a 0.35 (95 confidence interval: 0.20-0.51) lower performance test score, equivalent to the effect on performance of a 1-year increase in age. Exposure to air pollution was generally not associated with self-reported functional limitations, and not associated with the decline in performance-based physical functioning over the study period. Conclusions: This study suggests an adverse effect of exposure to air pollution on performance-based physical functioning of older adults in the Netherlands.

Air Pollution and Performance-Based Physical Functioning in Dutch Older Adults.

Background:Functional limitations are a major cause for needing care and institutionalization among older adults. Exposure to air pollution has been suggested to be associated with increased functional limitations in older people.Objective:Our objective was to assess the association between air pollution and physical functioning in Dutch older adults.Methods:We analyzed data on performance-based (walking speed, ability to rise from a chair, putting on and taking off a cardigan, balance test) and self-reported physical functioning for 1,762 participants of the Longitudinal Aging Study Amsterdam, who participated in measurement cycles performed in 2005/2006, 2008/2009, and 2011/2012. Annual average outdoor air pollution concentrations [nitrogen dioxide (), nitrogen oxides (), particulate matter with diameters (), (), and (), and absorbance] at the home address at the start of the first measurement cycle were estimated using land-use regression models. Analyses were performed using mixed models with random participant intercepts adjusting for potential confounders.Results:Exposure to most air pollutants was associated with reduced performance-based physical functioning; for example, an interquartile range increase in exposure was associated with a 0.22 (95% confidence interval: 0.03, 0.42) lower performance test score in fully adjusted models, equivalent to the difference in performance score between participants who differed by 9 mo in age. Exposure to air pollution was generally not statistically significantly associated with self-reported functional limitations, and not associated with a faster decline in performance-based physical functioning over the study period.Conclusion:This study suggests that exposure to air pollution may adversely affect physical performance of older adults in the Netherlands. https://doi.org/10.1289/EHP2239

Gestational diabetes mellitus and exposure to ambient air pollution and road traffic noise: A cohort study

BackgroundRoad traffic is a main source of air pollution and noise. Both exposures have been associated with type 2 diabetes, but associations with gestational diabetes mellitus (GDM) have been studied less. ObjectivesWe aimed to examine single and joint associations of exposure to air pollution and road traffic noise on GDM in a prospective cohort. MethodsWe identified GDM cases from self-reports and hospital records, using two different criteria, among 72,745 singleton pregnancies (1997–2002) from the Danish National Birth Cohort. We modeled nitrogen dioxide (NO2) and noise from road traffic (Lden) exposure at all pregnancy addresses. ResultsAccording to the two diagnostic criteria: the Danish clinical guidelines, which was our main outcome, and the WHO standard during recruitment period, a total of 565 and 210 women, respectively, had GDM. For both exposures no risk was evident for the common Danish criterion of GDM. A 10-μg/m3 increase in NO2 exposure during first trimester was, however, associated with an increased risk of WHO-GDM (adjusted odds ratio (OR)=1.24; 95% confidence interval (CI): 1.03, 1.49). The corresponding OR associated with a 10-dB higher road traffic noise level was 1.15 (0.94 to 1.18). In mutually adjusted models the OR for NO2 remained similar 1.22 (0.98, 1.53) whereas that for road traffic noise decreased to 1.03 (0.80, 1.32). Significant associations were also observed for exposure averaged over the 2nd and 3rd trimesters and the full pregnancy. ConclusionsNo risk was evident for the common Danish criterion of GDM. NO2 was associated with higher risk for GDM according to the WHO criterion, which might be due to selection bias.

Exposure to air pollution and noise from road traffic and risk of congenital anomalies in the Danish National Birth Cohort

Background:Ambient air pollution has been associated with certain congenital anomalies, but few studies rely on assessment of fine-scale variation in air quality and associations with noise from road traffic are unexplored. Methods:Among 84,218 liveborn singletons (1997–2002) from the Danish National Birth Cohort with complete covariate data and residential address history from conception until birth, we identified major congenital anomalies in 4018 children. Nitrogen dioxide (NO2) and noise from road traffic (Lden) burden during fetal life was modeled. Outcome and covariate data were derived from registries, hospital records and questionnaires. Odds ratios (ORs) for eleven major anomaly groups associated with road traffic pollution during first trimester were estimated using logistic regression with generalized estimating equation (GEE) approach. Results:Most of the associations tested did not suggest increased risks. A 10-µg/m3 increase in NO2 exposure during first trimester was associated with an adjusted ORs of 1.22 (95% confidence interval: 0.98–1.52) for ear, face and neck anomalies; 1.14 0.98–1.33) for urinary anomalies. A 10-dB increase in road traffic noise was also associated with these subgroups of anomalies as well as with an increased OR for orofacial cleft anomalies (1.17, 0.94–1.47). Inverse associations for several both air pollution and noise were observed for atrial septal defects (0.85, 0.68–1.04 and 0.81, 0.65–0.99, respectively). Conclusions:Residential road traffic exposure to noise or air pollution during pregnancy did not seem to pose a risk for development of congenital anomalies.

Impact of Road Traffic Pollution on Pre-eclampsia and Pregnancy-induced Hypertensive Disorders.

Road traffic is a major source of air pollution and noise. Both exposures have been associated with hypertension in adults, but pregnant women have been less studied. We examined single and joint effects of ambient air pollution and road traffic noise on pre-eclampsia and pregnancy-induced hypertensive disorders among 72,745 singleton pregnancies (1997-2002) from the Danish National Birth Cohort with complete covariate data and residential address history from conception until live born birth. Nitrogen dioxide (NO2) and noise from road traffic (Lden) were modeled at all addresses. Outcome and covariate data were derived from registries, hospital records, and questionnaires. A 10-µg/m increase in NO2 exposure during first trimester was associated with increased risk of pre-eclampsia (n = 1,880, adjusted odds ratio = 1.07 [95% confidence interval = 1.01, 1.14]) and pregnancy-induced hypertensive disorders (n = 2,430, adjusted odds ratio = 1.07 [1.01, 1.13]). A 10 dB higher road traffic noise was also associated with increased risk of pre-eclampsia (1.10 [1.02, 1.18]) and pregnancy-induced hypertensive disorders (1.08 [1.02, 1.15]). For both exposures, the associations were strongest for mild pre-eclampsia (n = 1,393) and early-onset pre-eclampsia (n = 671), whereas higher risk for severe pre-eclampsia (n = 487) was not evident. In mutually adjusted models, estimates for both exposures decreased and only the association between NO2 and mild pre-eclampsia remained. Road traffic may increase the risk of pre-eclampsia and hypertensive disorders in pregnancy through exposure to both ambient air pollution and noise, although associations with the two exposures were generally not found to be independent of one another. See video abstract, http://links.lww.com/EDE/B112.

Nitrogen dioxide pollution exposure is associated with olfactory dysfunction in older U.S. adults.

Olfactory dysfunction has profound effects on quality of life, physical and social function, and mortality itself. Nitrogen dioxide (NO2 ) is a pervasive air pollutant that is associated with respiratory diseases. Given the olfactory nerve's anatomic exposure to airborne pollutants, we investigated the relationship between NO2 exposure and olfactory dysfunction. The ability to identify odors was evaluated using a validated test in respondents from the National Social Life, Health, and Aging Project (NSHAP), a representative probability sample of home-dwelling, older U.S. adults age 57 to 85 years. Exposure to NO2 pollution was assessed using measurements obtained from the U.S. Environmental Protection Agency (EPA) Aerometric Information Retrieval System (AIRS) ambient monitoring site closest to each respondent's home. We tested the association between NO2 exposure and olfactory dysfunction using multivariate logistic regression. Among older adults in the United States, 22.6% had impaired olfactory function, defined as ≤3 correct (out of 5) on the odor identification test. Median NO2 exposure during the 365 days prior to the interview date was 14.7 ppb (interquartile range [IQR], 10.8 to 19.7 ppb). An IQR increase in NO2 exposure was associated with increased odds of olfactory dysfunction (OR, 1.35; 95% CI, 1.07 to 1.72), adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and season of the home interview (n = 1823). We show for the first time that NO2 exposure is associated with olfactory dysfunction in older U.S. adults. These results suggest an important role for NO2 exposure on olfactory dysfunction, and, potentially, nasal disease more broadly.

Dynamic assessment of exposure to air pollution using mobile phone data.

BackgroundExposure to air pollution can have major health impacts, such as respiratory and cardiovascular diseases. Traditionally, only the air pollution concentration at the home location is taken into account in health impact assessments and epidemiological studies. Neglecting individual travel patterns can lead to a bias in air pollution exposure assessments.MethodsIn this work, we present a novel approach to calculate the daily exposure to air pollution using mobile phone data of approximately 5 million mobile phone users living in Belgium. At present, this data is collected and stored by telecom operators mainly for management of the mobile network. Yet it represents a major source of information in the study of human mobility. We calculate the exposure to NO2 using two approaches: assuming people stay at home the entire day (traditional static approach), and incorporating individual travel patterns using their location inferred from their use of the mobile phone network (dynamic approach).ResultsThe mean exposure to NO2 increases with 1.27 μg/m3 (4.3 %) during the week and with 0.12 μg/m3 (0.4 %) during the weekend when incorporating individual travel patterns. During the week, mostly people living in municipalities surrounding larger cities experience the highest increase in NO2 exposure when incorporating their travel patterns, probably because most of them work in these larger cities with higher NO2 concentrations.ConclusionsIt is relevant for health impact assessments and epidemiological studies to incorporate individual travel patterns in estimating air pollution exposure. Mobile phone data is a promising data source to determine individual travel patterns, because of the advantages (e.g. low costs, large sample size, passive data collection) compared to travel surveys, GPS, and smartphone data (i.e. data captured by applications on smartphones).

Exposure to traffic-related air pollution and the risk of developing breast cancer among women in eight Canadian provinces: A case–control study

A few recent studies have reported positive associations between long-term exposure to traffic-related air pollution and the incidence of breast cancer. We capitalized on an existing Canadian multi-site population-based case–control study to further investigate this association.We used the National Enhanced Cancer Surveillance System, a population-based case–control study conducted in eight of 10 Canadian provinces from 1994 to 1997. A total of 1569 breast cancer cases and 1872 population controls who reported at least 90% complete self-reported addresses over the 1975–1994 exposure period were examined. Mean exposure levels to nitrogen dioxide (NO2) (an indicator of traffic-related air pollution) were estimated for this period using three different measures: (1) satellite-derived observations; (2) satellite-derived observations scaled with historical fixed-site measurements of NO2; and (3) a national land-use regression (LUR) model. Proximity to major roads was also examined. Using unconditional logistic regression, stratified by menopausal status, we estimated odds ratios (ORs) adjusted for many individual-level and contextual breast cancer risk factors.We observed positive associations between incident breast cancer and all three measures of NO2 exposure from 1975 to 1994. In fully adjusted models for premenopausal breast cancer, a 10ppb increase in NO2 exposure estimated from the satellite-derived observations, the scaled satellite-derived observations, and the national LUR model produced ORs of 1.26 (95% confidence intervals (CIs): 0.92–1.74), 1.32 (95% CI: 1.05–1.67) and 1.28 (95% CI: 0.92–1.79). For postmenopausal breast cancer, we found corresponding ORs of 1.10 (95% CI: 0.88–1.36), 1.10 (95% CI: 0.94–1.28) and 1.07 (95% CI: 0.86–1.32). Substantial heterogeneity in the ORs was observed across the eight Canadian provinces and reduced ORs were observed when models were restricted to women who had received routine mammography examinations. No associations were found for road proximity measures.This study provides some support for the hypothesis that traffic-related air pollution may be associated with the development of breast cancer, especially in premenopausal women. With the few studies available, further research is clearly needed.

Air Pollution and Biomarkers of Systemic Inflammation and Tissue Repair in COPD Patients

The origin(s) of systemic inflammation in patients with chronic obstructive pulmonary disease (COPD) is unclear. We investigated the impact of exposure to ambient air pollution on systemic biomarkers of inflammation (C-reactive protein (CRP), tumour necrosis factor-α, interleukin (IL)-6, IL-8 and fibrinogen) and tissue repair (hepatocyte growth factor (HGF)) in 242 clinically stable COPD patients (mean age 67.8 years and forced expiratory volume in 1 s 71.3% predicted) in Barcelona, Spain, in 2004-2006. A spatiotemporal exposure assessment framework was applied to predict ambient nitrogen dioxide (NO2) and levels of particles with a 50% cut-off aerodynamic diameter of 2.5 μm (PM2.5) at each participant's home address during 10 periods of 24 h (lags 1-10) and 1 year prior to the blood sampling date. We used linear regression models to estimate associations between biomarkers and exposure levels. An interquartile range (IQR) increase in NO2 exposure in lag 5 was associated with 51%, 10% and 9% increases in CRP, fibrinogen and HGF levels respectively. We also observed 12% and 8% increases in IL-8 associated with an IQR increase in NO2 exposure in lag 3 and over the year before sampling, respectively. These increases were larger in former smokers. The results for PM2.5 were not conclusive. These results show that exposure to ambient NO2 increases systemic inflammation in COPD patients, especially in former smokers.

Adult lung function and long-term air pollution exposure. ESCAPE: a multicentre cohort study and meta-analysis.

The chronic impact of ambient air pollutants on lung function in adults is not fully understood. The objective of this study was to investigate the association of long-term exposure to ambient air pollution with lung function in adult participants from five cohorts in the European Study of Cohorts for Air Pollution Effects (ESCAPE).Residential exposure to nitrogen oxides (NO2, NOx) and particulate matter (PM) was modelled and traffic indicators were assessed in a standardised manner. The spirometric parameters forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) from 7613 subjects were considered as outcomes. Cohort-specific results were combined using meta-analysis.We did not observe an association of air pollution with longitudinal change in lung function, but we observed that a 10 μg·m−3 increase in NO2 exposure was associated with lower levels of FEV1 (−14.0 mL, 95% CI −25.8 to −2.1) and FVC (−14.9 mL, 95% CI −28.7 to −1.1). An increase of 10 μg·m−3 in PM10, but not other PM metrics (PM2.5, coarse fraction of PM, PM absorbance), was associated with a lower level of FEV1 (−44.6 mL, 95% CI −85.4 to −3.8) and FVC (−59.0 mL, 95% CI −112.3 to −5.6). The associations were particularly strong in obese persons.This study adds to the evidence for an adverse association of ambient air pollution with lung function in adults at very low levels in Europe.

Air pollution and biomarkers of systemic inflammation and tissue repair in COPD patients.

The origin(s) of systemic inflammation in patients with chronic obstructive pulmonary disease (COPD) is unclear. We investigated the impact of exposure to ambient air pollution on systemic biomarkers of inflammation (C-reactive protein (CRP), tumour necrosis factor-α, interleukin (IL)-6, IL-8 and fibrinogen) and tissue repair (hepatocyte growth factor (HGF)) in 242 clinically stable COPD patients (mean age 67.8 years and forced expiratory volume in 1 s 71.3% predicted) in Barcelona, Spain, in 2004-2006. A spatiotemporal exposure assessment framework was applied to predict ambient nitrogen dioxide (NO2) and levels of particles with a 50% cut-off aerodynamic diameter of 2.5 μm (PM2.5) at each participant's home address during 10 periods of 24 h (lags 1-10) and 1 year prior to the blood sampling date. We used linear regression models to estimate associations between biomarkers and exposure levels. An interquartile range (IQR) increase in NO2 exposure in lag 5 was associated with 51%, 10% and 9% increases in CRP, fibrinogen and HGF levels respectively. We also observed 12% and 8% increases in IL-8 associated with an IQR increase in NO2 exposure in lag 3 and over the year before sampling, respectively. These increases were larger in former smokers. The results for PM2.5 were not conclusive. These results show that exposure to ambient NO2 increases systemic inflammation in COPD patients, especially in former smokers.

Association between long-term exposure to traffic-related air pollution and lung function: the European Study of Cohorts for Air Pollution Effects (ESCAPE)

Background. Acute air pollution effects on lung function are well established and evidence is also strong for long-term effects on lung function growth in children. The chronic impact of ambient air pollutants on lung function in adults remains poorly understood. Aims. We investigated the association of residential traffic-related air pollution with level and decline of lung function in the context of five European cohorts of adults (ECRHS, EGEA, NSHD, SALIA, SAPALDIA). Methods. Residential exposure to nitrogen oxides (NO2, NOx) and particulate matter (PM) was obtained from standardized measurement protocols and land use regression models. Traffic load at the road nearest to participants’ home and on major roads within a 100 meter buffer was assessed. Study-specific analyses were performed with random effects linear regression adjusting for gender, age, height, BMI, education, smoking status. The level and annual decline in the spirometric parameters FEV1, FVC, and FEV1/FVC were considered as outcomes. Cohort-specific results were combined using random-effects meta-analysis. Results. Based on lung function data from 7,613 subjects undergoing spirometry twice over a period of 11 years on average, we observed that a 10 µg/m3 increase in NO2 exposure was associated with lower levels of FEV1 (-13.8 mL (95%CI: -25.82, -2.14)) and FVC (-14.93 mL (-28.73,-1.13)). A higher traffic load at the home address also went along with lower levels of FEV1 and FEV1/FVC. The observed associations were particularly observed in women and generally stronger in participants reporting use of respiratory medication. None of the lung function parameters was related to PM exposure. Conclusions. In this analysis of adults mostly living in urban environments, we observed a lung function decline with increased nitrogen oxide or traffic load exposure. The reported gender differences stimulate research into the underlying mechanisms.

Household Levels of Nitrogen Dioxide and Pediatric Asthma Severity

Adverse respiratory effects in children with asthma are associated with exposures to nitrogen dioxide (NO2). Levels indoors can be much higher than outdoors. Primary indoor sources of NO2 are gas stoves, which are used for cooking by one-third of U.S. households. We investigated the effects of indoor NO2 exposure on asthma severity among an ethnically and economically diverse sample of children, controlling for season and indoor allergen exposure. Children 5-10 years of age with active asthma (n = 1,342) were recruited through schools in urban and suburban Connecticut and Massachusetts (2006-2009) for a prospective, year-long study with seasonal measurements of NO2 and asthma severity. Exposure to NO2 was measured passively for four, month-long, periods with Palmes tubes. Asthma morbidity was concurrently measured by a severity score and frequency of wheeze, night symptoms, and use of rescue medication. We used adjusted, hierarchical ordered logistic regression models to examine associations between household NO2 exposure and health outcomes. Every 5-fold increase in NO2 exposure above a threshold of 6 ppb was associated with a dose-dependent increase in risk of higher asthma severity score (odds ratio = 1.37 [95% confidence interval = 1.01-1.89]), wheeze (1.49 [1.09-2.03]), night symptoms (1.52 [1.16-2.00]), and rescue medication use (1.78 [1.33-2.38]). Asthmatic children exposed to NO2 indoors, at levels well below the U.S. Environmental Protection Agency outdoor standard (53 ppb), are at risk for increased asthma morbidity. Risks are not confined to inner city children, but occur at NO2 concentrations common in urban and suburban homes.

Residential Exposure to Outdoor Air Pollution during Pregnancy and Anthropometric Measures at Birth in a Multicenter Cohort in Spain

Background: A growing body of research suggests that prenatal exposure to air pollution may be harmful to fetal development. We assessed the association between exposure to air pollution during pregnancy and anthropometric measures at birth in four areas within the Spanish Children’s Health and Environment (INMA) mother and child cohort study.Methods: Exposure to ambient nitrogen dioxide (NO2) and benzene was estimated for the residence of each woman (n = 2,337) for each trimester and for the entire pregnancy. Outcomes included birth weight, length, and head circumference. The association between residential outdoor air pollution exposure and birth outcomes was assessed with linear regression models controlled for potential confounders. We also performed sensitivity analyses for the subset of women who spent more time at home during pregnancy. Finally, we performed a combined analysis with meta-analysis techniques.Results: In the combined analysis, an increase of 10 µg/m3 in NO2 exposure during pregnancy was associated with a decrease in birth length of –0.9 mm [95% confidence interval (CI), –1.8 to –0.1 mm]. For the subset of women who spent ≥ 15 hr/day at home, the association was stronger (–0.16 mm; 95% CI, –0.27 to –0.04). For this same subset of women, a reduction of 22 g in birth weight was associated with each 10-µg/m3 increase in NO2 exposure in the second trimester (95% CI, –45.3 to 1.9). We observed no significant relationship between benzene levels and birth outcomes.Conclusions: NO2 exposure was associated with reductions in both length and weight at birth. This association was clearer for the subset of women who spent more time at home.

Maternal Exposure to Nitrogen Dioxide during Pregnancy and Offspring Birth Weight: Comparison of Two Exposure Models

BackgroundStudies of the effects of air pollutants on birth weight often assess exposure with networks of permanent air quality monitoring stations (AQMSs), which have a poor spatial resolution.ObjectiveWe aimed to compare the exposure model based on the nearest AQMS and a temporally adjusted geostatistical (TAG) model with a finer spatial resolution, for use in pregnancy studies.MethodsThe AQMS and TAG exposure models were implemented in two areas surrounding medium-size cities in which 776 pregnant women were followed as part of the EDEN mother–child cohort. The exposure models were compared in terms of estimated nitrogen dioxide (NO2) levels and of their association with birth weight.ResultsThe correlations between the two estimates of exposure during the first trimester of pregnancy were r = 0.67, 0.70, and 0.83 for women living within 5, 2, and 1 km of an AQMS, respectively. Exposure patterns displayed greater spatial than temporal variations. Exposure during the first trimester of pregnancy was most strongly associated with birth weight for women living < 2 km away from an AQMS: a 10-μg/m3 increase in NO2 exposure was associated with an adjusted difference in birth weight of −37 g [95% confidence interval (CI), −75 to 1 g] for the nearest-AQMS model and of −51 g (95% CI, −128 to 26 g) for the TAG model. The association was less strong (higher p-value) for women living within 5 or 1 km of an AQMS.ConclusionsThe two exposure models tended to give consistent results in terms of association with birth weight, despite the moderate concordance between exposure estimates.

A Longitudinal Study of Indoor Nitrogen Dioxide Levels and Respiratory Symptoms in Inner-City Children with Asthma

BackgroundThe effect of indoor nitrogen dioxide concentrations on asthma morbidity among inner-city preschool children is uncertain.ObjectivesOur goal was to estimate the effect of indoor NO2 concentrations on asthma morbidity in an inner-city population while adjusting for other indoor pollutants.MethodsWe recruited 150 children (2–6 years of age) with physician-diagnosed asthma from inner-city Baltimore, Maryland. Indoor air was monitored over a 72-hr period in the children’s bedrooms at baseline and 3 and 6 months. At each visit, the child’s caregiver completed a questionnaire assessing asthma symptoms over the previous 2 weeks and recent health care utilization.ResultsChildren were 58% male, 91% African American, and 42% from households with annual income < $25,000; 63% had persistent asthma symptoms. The mean (± SD) in-home NO2 concentration was 30.0 ± 33.7 (range, 2.9–394.0) ppb. The presence of a gas stove and the use of a space heater or oven/stove for heat were independently associated with higher NO2 concentrations. Each 20-ppb increase in NO2 exposure was associated significantly with an increase in the number of days with limited speech [incidence rate ratio (IRR) = 1.15; 95% confidence interval (CI), 1.05–1.25], cough (IRR = 1.10; 95% CI, 1.02–1.18), and nocturnal symptoms (IRR = 1.09; 95% CI, 1.02–1.16), after adjustment for potential confounders. NO2 concentrations were not associated with increased health care utilization.ConclusionsHigher indoor NO2 concentrations were associated with increased asthma symptoms in preschool inner-city children. Interventions aimed at lowering NO2 concentrations in inner-city homes may reduce asthma morbidity in this vulnerable population.