The effect of air pollution on lung development from 10 to 18 years of age

BACKGROUND

Whether exposure to air pollution adversely affects the growth of lung function during the period of rapid lung development that occurs between the ages of 10 and 18 years is unknown.

METHODS

In this prospective study, we recruited 1759 children (average age, 10 years) from schools in 12 southern California communities and measured lung function annually for eight years. The rate of attrition was approximately 10 percent per year. The communities represented a wide range of ambient exposures to ozone, acid vapor, nitrogen dioxide, and particulate matter. Linear regression was used to examine the relationship of air pollution to the forced expiratory volume in one second (FEV(1)) and other spirometric measures.

RESULTS

Over the eight-year period, deficits in the growth of FEV(1) were associated with exposure to nitrogen dioxide (P=0.005), acid vapor (P=0.004), particulate matter with an aerodynamic diameter of less than 2.5 microm (PM(2.5)) (P=0.04), and elemental carbon (P=0.007), even after adjustment for several potential confounders and effect modifiers. Associations were also observed for other spirometric measures. Exposure to pollutants was associated with clinically and statistically significant deficits in the FEV(1) attained at the age of 18 years. For example, the estimated proportion of 18-year-old subjects with a low FEV(1) (defined as a ratio of observed to expected FEV(1) of less than 80 percent) was 4.9 times as great at the highest level of exposure to PM(2.5) as at the lowest level of exposure (7.9 percent vs. 1.6 percent, P=0.002).

CONCLUSIONS

The results of this study indicate that current levels of air pollution have chronic, adverse effects on lung development in children from the age of 10 to 18 years, leading to clinically significant deficits in attained FEV(1) as children reach adulthood.

Effect of exposure to traffic on lung development from 10 to 18 years of age: a cohort study

BACKGROUND

Whether local exposure to major roadways adversely affects lung-function growth during the period of rapid lung development that takes place between 10 and 18 years of age is unknown. This study investigated the association between residential exposure to traffic and 8-year lung-function growth.

METHODS

In this prospective study, 3677 children (mean age 10 years [SD 0.44]) participated from 12 southern California communities that represent a wide range in regional air quality. Children were followed up for 8 years, with yearly lung-function measurements recorded. For each child, we identified several indicators of residential exposure to traffic from large roads. Regression analysis was used to establish whether 8-year growth in lung function was associated with local traffic exposure, and whether local traffic effects were independent of regional air quality.

FINDINGS

Children who lived within 500 m of a freeway (motorway) had substantial deficits in 8-year growth of forced expiratory volume in 1 s (FEV(1), -81 mL, p=0.01 [95% CI -143 to -18]) and maximum midexpiratory flow rate (MMEF, -127 mL/s, p=0.03 [-243 to -11), compared with children who lived at least 1500 m from a freeway. Joint models showed that both local exposure to freeways and regional air pollution had detrimental, and independent, effects on lung-function growth. Pronounced deficits in attained lung function at age 18 years were recorded for those living within 500 m of a freeway, with mean percent-predicted 97.0% for FEV1 (p=0.013, relative to >1500 m [95% CI 94.6-99.4]) and 93.4% for MMEF (p=0.006 [95% CI 89.1-97.7]).

INTERPRETATION

Local exposure to traffic on a freeway has adverse effects on children's lung development, which are independent of regional air quality, and which could result in important deficits in attained lung function in later life.

Association of improved air quality with lung development in children

BACKGROUND

Air-pollution levels have been trending downward progressively over the past several decades in southern California, as a result of the implementation of air quality-control policies. We assessed whether long-term reductions in pollution were associated with improvements in respiratory health among children.

METHODS

As part of the Children's Health Study, we measured lung function annually in 2120 children from three separate cohorts corresponding to three separate calendar periods: 1994-1998, 1997-2001, and 2007-2011. Mean ages of the children within each cohort were 11 years at the beginning of the period and 15 years at the end. Linear-regression models were used to examine the relationship between declining pollution levels over time and lung-function development from 11 to 15 years of age, measured as the increases in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) during that period (referred to as 4-year growth in FEV1 and FVC).

RESULTS

Over the 13 years spanned by the three cohorts, improvements in 4-year growth of both FEV1 and FVC were associated with declining levels of nitrogen dioxide (P<0.001 for FEV1 and FVC) and of particulate matter with an aerodynamic diameter of less than 2.5 μm (P= 0.008 for FEV1 and P<0.001 for FVC) and less than 10 μm (P<0.001 for FEV1 and FVC). These associations persisted after adjustment for several potential confounders. Significant improvements in lung-function development were observed in both boys and girls and in children with asthma and children without asthma. The proportions of children with clinically low FEV1 (defined as <80% of the predicted value) at 15 years of age declined significantly, from 7.9% to 6.3% to 3.6% across the three periods, as the air quality improved (P = 0.001).

CONCLUSIONS

We found that long-term improvements in air quality were associated with statistically and clinically significant positive effects on lung-function growth in children. (Funded by the Health Effects Institute and others.).

Traffic-related air pollution, particulate matter, and autism

CONTEXT

Autism is a heterogeneous disorder with genetic and environmental factors likely contributing to its origins. Examination of hazardous pollutants has suggested the importance of air toxics in the etiology of autism, yet little research has examined its association with local levels of air pollution using residence-specific exposure assignments.

OBJECTIVE

To examine the relationship between traffic-related air pollution, air quality, and autism.

DESIGN

This population-based case-control study includes data obtained from children with autism and control children with typical development who were enrolled in the Childhood Autism Risks from Genetics and the Environment study in California. The mother's address from the birth certificate and addresses reported from a residential history questionnaire were used to estimate exposure for each trimester of pregnancy and first year of life. Traffic-related air pollution was assigned to each location using a line-source air-quality dispersion model. Regional air pollutant measures were based on the Environmental Protection Agency's Air Quality System data. Logistic regression models compared estimated and measured pollutant levels for children with autism and for control children with typical development.

SETTING

Case-control study from California.

PARTICIPANTS

A total of 279 children with autism and a total of 245 control children with typical development.

MAIN OUTCOME MEASURES

Crude and multivariable adjusted odds ratios (AORs) for autism.

RESULTS

Children with autism were more likely to live at residences that had the highest quartile of exposure to traffic-related air pollution, during gestation (AOR, 1.98 [95% CI, 1.20-3.31]) and during the first year of life (AOR, 3.10 [95% CI, 1.76-5.57]), compared with control children. Regional exposure measures of nitrogen dioxide and particulate matter less than 2.5 and 10 μm in diameter (PM2.5 and PM10) were also associated with autism during gestation (exposure to nitrogen dioxide: AOR, 1.81 [95% CI, 1.37-3.09]; exposure to PM2.5: AOR, 2.08 [95% CI, 1.93-2.25]; exposure to PM10: AOR, 2.17 [95% CI, 1.49-3.16) and during the first year of life (exposure to nitrogen dioxide: AOR, 2.06 [95% CI, 1.37-3.09]; exposure to PM2.5: AOR, 2.12 [95% CI, 1.45-3.10]; exposure to PM10: AOR, 2.14 [95% CI, 1.46-3.12]). All regional pollutant estimates were scaled to twice the standard deviation of the distribution for all pregnancy estimates.

CONCLUSIONS

Exposure to traffic-related air pollution, nitrogen dioxide, PM2.5, and PM10 during pregnancy and during the first year of life was associated with autism. Further epidemiological and toxicological examinations of likely biological pathways will help determine whether these associations are causal.

Traffic, susceptibility, and childhood asthma

Results from studies of traffic and childhood asthma have been inconsistent, but there has been little systematic evaluation of susceptible subgroups. In this study, we examined the relationship of local traffic-related exposure and asthma and wheeze in southern California school children (5-7 years of age). Lifetime history of doctor-diagnosed asthma and prevalent asthma and wheeze were evaluated by questionnaire. Parental history of asthma and child's history of allergic symptoms, sex, and early-life exposure (residence at the same home since 2 years of age) were examined as susceptibility factors. Residential exposure was assessed by proximity to a major road and by modeling exposure to local traffic-related pollutants. Residence within 75 m of a major road was associated with an increased risk of lifetime asthma [odds ratio (OR)=1.29; 95% confidence interval (CI), 1.01-1.86], prevalent asthma (OR=1.50; 95% CI, 1.16-1.95), and wheeze (OR=1.40; 95% CI, 1.09-1.78). Susceptibility increased in long-term residents with no parental history of asthma for lifetime asthma (OR=1.85; 95% CI, 1.11-3.09), prevalent asthma (OR=2.46; 95% CI, 0.48-4.09), and recent wheeze (OR=2.74; 95% CI, 1.71-4.39). The higher risk of asthma near a major road decreased to background rates at 150-200 m from the road. In children with a parental history of asthma and in children moving to the residence after 2 years of age, there was no increased risk associated with exposure. Effect of residential proximity to roadways was also larger in girls. A similar pattern of effects was observed with traffic-modeled exposure. These results indicate that residence near a major road is associated with asthma. The reason for larger effects in those with no parental history of asthma merits further investigation.

Childhood incident asthma and traffic-related air pollution at home and school

BACKGROUND

Traffic-related air pollution has been associated with adverse cardiorespiratory effects, including increased asthma prevalence. However, there has been little study of effects of traffic exposure at school on new-onset asthma.

OBJECTIVES

We evaluated the relationship of new-onset asthma with traffic-related pollution near homes and schools.

METHODS

Parent-reported physician diagnosis of new-onset asthma (n = 120) was identified during 3 years of follow-up of a cohort of 2,497 kindergarten and first-grade children who were asthma- and wheezing-free at study entry into the Southern California Children's Health Study. We assessed traffic-related pollution exposure based on a line source dispersion model of traffic volume, distance from home and school, and local meteorology. Regional ambient ozone, nitrogen dioxide (NO(2)), and particulate matter were measured continuously at one central site monitor in each of 13 study communities. Hazard ratios (HRs) for new-onset asthma were scaled to the range of ambient central site pollutants and to the residential interquartile range for each traffic exposure metric.

RESULTS

Asthma risk increased with modeled traffic-related pollution exposure from roadways near homes [HR 1.51; 95% confidence interval (CI), 1.25-1.82] and near schools (HR 1.45; 95% CI, 1.06-1.98). Ambient NO(2) measured at a central site in each community was also associated with increased risk (HR 2.18; 95% CI, 1.18-4.01). In models with both NO(2) and modeled traffic exposures, there were independent associations of asthma with traffic-related pollution at school and home, whereas the estimate for NO(2) was attenuated (HR 1.37; 95% CI, 0.69-2.71).

CONCLUSIONS

Traffic-related pollution exposure at school and homes may both contribute to the development of asthma.

Childhood asthma and exposure to traffic and nitrogen dioxide

BACKGROUND

Evidence for a causal relationship between traffic-related air pollution and asthma has not been consistent across studies, and comparisons among studies have been difficult because of the use of different indicators of exposure.

METHODS

We examined the association between traffic-related pollution and childhood asthma in 208 children from 10 southern California communities using multiple indicators of exposure. Study subjects were randomly selected from participants in the Children's Health Study. Outdoor nitrogen dioxide (NO2) was measured in summer and winter outside the home of each child. We also determined residential distance to the nearest freeway, traffic volumes on roadways within 150 meters, and model-based estimates of pollution from nearby roadways.

RESULTS

Lifetime history of doctor-diagnosed asthma was associated with outdoor NO2; the odds ratio (OR) was 1.83 (95% confidence interval=1.04-3.22) per increase of 1 interquartile range (IQR=5.7 ppb) in exposure. We also observed increased asthma associated with closer residential distance to a freeway (1.89 per IQR; 1.19-3.02) and with model-based estimates of outdoor pollution from a freeway (2.22 per IQR; 1.36-3.63). These 2 indicators of freeway exposure and measured NO2 concentrations were also associated with wheezing and use of asthma medication. Asthma was not associated with traffic volumes on roadways within 150 meters of homes or with model-based estimates of pollution from nonfreeway roads.

CONCLUSIONS

These results indicate that respiratory health in children is adversely affected by local exposures to outdoor NO2 or other freeway-related pollutants.

Residential proximity to freeways and autism in the CHARGE study

BACKGROUND

Little is known about environmental causes and contributing factors for autism. Basic science and epidemiologic research suggest that oxidative stress and inflammation may play a role in disease development. Traffic-related air pollution, a common exposure with established effects on these pathways, contains substances found to have adverse prenatal effects.

OBJECTIVES

We examined the association between autism and proximity of residence to freeways and major roadways during pregnancy and near the time of delivery, as a surrogate for air pollution exposure.

METHODS

Data were from 304 autism cases and 259 typically developing controls enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) study. The mother's address recorded on the birth certificate and trimester-specific addresses derived from a residential history obtained by questionnaire were geocoded, and measures of distance to freeways and major roads were calculated using ArcGIS software. Logistic regression models compared residential proximity to freeways and major roads for autism cases and typically developing controls.

RESULTS

Adjusting for sociodemographic factors and maternal smoking, maternal residence at the time of delivery was more likely be near a freeway (≤ 309 m) for cases than for controls [odds ratio (OR)=1.86; 95% confidence interval (CI), 1.04-3.45]. Autism was also associated with residential proximity to a freeway during the third trimester (OR=2.22; CI, 1.16-4.42). After adjustment for socioeconomic and sociodemographic characteristics, these associations were unchanged. Living near other major roads at birth was not associated with autism.

CONCLUSIONS

Living near a freeway was associated with autism. Examination of associations with measured air pollutants is needed.

A study of twelve Southern California communities with differing levels and types of air pollution. I. Prevalence of respiratory morbidity

To study possible chronic respiratory effects of air pollutants, we initiated a 10-yr prospective cohort study of Southern California children, with a study design focused on four pollutants: ozone, particulate matter, acids, and nitrogen dioxide (NO2). Twelve demographically similar communities were selected on the basis of historic monitoring information to represent extremes of exposure to one or more pollutants. In each community, about 150 public school students in grade 4, 75 in grade 7, and 75 in grade 10 were enrolled through their classrooms. Informed consent and written responses to surveys about students' lifetime residential histories, historic and current health status, residential characteristics, and physical activity were obtained with the help of the parents. In the first testing season, 3,676 students returned questionnaires. We confirmed associations previously reported between respiratory morbidity prevalence and the presence of personal, demographic, and residential risk factors. Rates of respiratory illness were higher for males, those living in houses with pets, pests, mildew, and water damage, those whose parents had asthma, and those living in houses with smokers. Wheeze prevalence was positively associated with levels of both acid (odds ratio [OR] = 1.45; 95% confidence interval [CI], 1.14-1.83) and NO2 (OR = 1.54; 95% CI, 1.08-2.19) in boys. We conclude, based on this cross-sectional assessment of questionnaire responses, that current levels of ambient air pollution in Southern California may be associated with effects on schoolchildren's respiratory morbidity as assessed by questionnaire.

Early-life air pollution and asthma risk in minority children. The GALA II and SAGE II studies

RATIONALE

Air pollution is a known asthma trigger and has been associated with short-term asthma symptoms, airway inflammation, decreased lung function, and reduced response to asthma rescue medications.

OBJECTIVES

To assess a causal relationship between air pollution and childhood asthma using data that address temporality by estimating air pollution exposures before the development of asthma and to establish the generalizability of the association by studying diverse racial/ethnic populations in different geographic regions.

METHODS

This study included Latino (n = 3,343) and African American (n = 977) participants with and without asthma from five urban regions in the mainland United States and Puerto Rico. Residential history and data from local ambient air monitoring stations were used to estimate average annual exposure to five air pollutants: ozone, nitrogen dioxide (NO₂), sulfur dioxide, particulate matter not greater than 10 μm in diameter, and particulate matter not greater than 2.5 μm in diameter. Within each region, we performed logistic regression to determine the relationship between early-life exposure to air pollutants and subsequent asthma diagnosis. A random-effects model was used to combine the region-specific effects and generate summary odds ratios for each pollutant.

MEASUREMENTS AND MAIN RESULTS

After adjustment for confounders, a 5-ppb increase in average NO₂ during the first year of life was associated with an odds ratio of 1.17 for physician-diagnosed asthma (95% confidence interval, 1.04-1.31).

CONCLUSIONS

Early-life NO₂ exposure is associated with childhood asthma in Latinos and African Americans. These results add to a growing body of evidence that traffic-related pollutants may be causally related to childhood asthma.

Association between air pollution and lung function growth in southern California children

Average growth of lung function over a 4-yr period, in three cohorts of southern California children who were in the fourth, seventh, or tenth grade in 1993, was modeled as a function of average exposure to ambient air pollutants. In the fourth-grade cohort, significant deficits in growth of lung function (FEV(1), FVC, maximal midexpiratory flow [MMEF], and FEF(75)) were associated with exposure to particles with aerodynamic diameter less than 10 micrometer (PM(10)), PM(2.5), PM(10)-PM(2.5), NO(2), and inorganic acid vapor (p < 0.05). No significant associations were observed with ozone. The estimated growth rate for children in the most polluted of the communities as compared with the least polluted was predicted to result in a cumulative reduction of 3.4% in FEV(1) and 5.0% in MMEF over the 4-yr study period. The estimated deficits were generally larger for children spending more time outdoors. In the seventh- and tenth-grade cohorts, the estimated pollutant effects were also negative for most lung function measures, but sample sizes were lower in these groups and none achieved statistical significance. The results suggest that significant negative effects on lung function growth in children occur at current ambient concentrations of particles, NO(2), and inorganic acid vapor.

Association between air pollution and lung function growth in southern California children: results from a second cohort

A cohort of 1,678 Southern California children, enrolled as fourth graders in 1996, was followed for 4 years to determine whether the growth in lung function of the children was associated with their exposure to ambient air pollutants. These subjects comprised the second cohort of fourth grade children participating in the Children's Health Study. Significant deficits in lung function growth rate were associated with exposure to acid vapor, NO(2), particles with aerodynamic diameter less than 2.5 microm (PM(2.5)), and elemental carbon. For example, the average annual growth rates of maximal midexpiratory flow and forced expiratory volume in 1 second were reduced by approximately 11% (p = 0.005) and 5% (p = 0.03), respectively, across the observed range of acid exposure. Exposure to acid vapor was also associated with reductions in the ratio of maximal midexpiratory flow to forced vital capacity (p = 0.02), whereas exposure to ozone was correlated with reduced growth in peak flow rate (p = 0.006). Larger deficits in lung function growth rate were observed in children who reported spending more time outdoors. These findings provide important replication of our previous findings of an effect of air pollution on lung function growth that were based on the first fourth-grade cohort from the Children's Health Study (Am J Respir Crit Care Med 2000;162:1383-1390).

Traffic-related air pollution and asthma onset in children: a prospective cohort study with individual exposure measurement

BACKGROUND

The question of whether air pollution contributes to asthma onset remains unresolved.

OBJECTIVES

In this study, we assessed the association between asthma onset in children and traffic-related air pollution.

METHODS

We selected a sample of 217 children from participants in the Southern California Children's Health Study, a prospective cohort designed to investigate associations between air pollution and respiratory health in children 10-18 years of age. Individual covariates and new asthma incidence (30 cases) were reported annually through questionnaires during 8 years of follow-up. Children had nitrogen dioxide monitors placed outside their home for 2 weeks in the summer and 2 weeks in the fall-winter season as a marker of traffic-related air pollution. We used multilevel Cox models to test the associations between asthma and air pollution.

RESULTS

In models controlling for confounders, incident asthma was positively associated with traffic pollution, with a hazard ratio (HR) of 1.29 [95% confidence interval (CI), 1.07-1.56] across the average within-community interquartile range of 6.2 ppb in annual residential NO2. Using the total interquartile range for all measurements of 28.9 ppb increased the HR to 3.25 (95% CI, 1.35-7.85).

CONCLUSIONS

In this cohort, markers of traffic-related air pollution were associated with the onset of asthma. The risks observed suggest that air pollution exposure contributes to new-onset asthma.

Components of air pollution and cognitive function in middle-aged and older adults in Los Angeles

While experiments in animals demonstrate neurotoxic effects of particulate matter (PM) and ozone (O3), epidemiologic evidence is sparse regarding the relationship between different constituencies of air pollution mixtures and cognitive function in adults. We examined cross-sectional associations between various ambient air pollutants [O3, PM2.5 and nitrogen dioxide (NO2)] and six measures of cognitive function and global cognition among healthy, cognitively intact individuals (n=1496, mean age 60.5 years) residing in the Los Angeles Basin. Air pollution exposures were assigned to each residential address in 2000-06 using a geographic information system that included monitoring data. A neuropsychological battery was used to assess cognitive function; a principal components analysis defined six domain-specific functions and a measure of global cognitive function was created. Regression models estimated effects of air pollutants on cognitive function, adjusting for age, gender, race, education, income, study and mood. Increasing exposure to PM2.5 was associated with lower verbal learning (β=-0.32 per 10 μg/m(3) PM2.5, 95% CI=-0.63, 0.00; p=0.05). Ambient exposure to NO2 >20 ppb tended to be associated with lower logical memory. Compared to the lowest level of exposure to ambient O3, exposure above 49 ppb was associated with lower executive function. Including carotid artery intima-media thickness, a measure of subclinical atherosclerosis, in models as a possible mediator did not attenuate effect estimates. This study provides support for cross-sectional associations between increasing levels of ambient O3, PM2.5 and NO2 and measures of domain-specific cognitive abilities.

Air pollution and bronchitic symptoms in Southern California children with asthma

The association of air pollution with the prevalence of chronic lower respiratory tract symptoms among children with a history of asthma or related symptoms was examined in a cross-sectional study. Parents of a total of 3,676 fourth, seventh, and tenth graders from classrooms in 12 communities in Southern California completed questionnaires that characterized the children's histories of respiratory illness and associated risk factors. The prevalences of bronchitis, chronic phlegm, and chronic cough were investigated among children with a history of asthma, wheeze without diagnosed asthma, and neither wheeze nor asthma. Average ambient annual exposure to ozone, particulate matter (PM(10) and PM(2.5); [less than/equal to] 10 microm and < 2.5 microm in aerodynamic diameter, respectively), acid vapor, and nitrogen dioxide (NO(2)) was estimated from monitoring stations in each community. Positive associations between air pollution and bronchitis and phlegm were observed only among children with asthma. As PM(10) increased across communities, there was a corresponding increase in the risk per interquartile range of bronchitis [odds ratio (OR) 1.4/19 microg/m(3); 95% confidence interval (CI), 1.1-1.8). Increased prevalence of phlegm was significantly associated with increasing exposure to all ambient pollutants except ozone. The strongest association was for NO(2), based on relative risk per interquartile range in the 12 communities (OR 2.7/24 ppb; CI, 1.4-5.3). The results suggest that children with a prior diagnosis of asthma are more likely to develop persistent lower respiratory tract symptoms when exposed to air pollution in Southern California.

Traffic-related air pollution and obesity formation in children: a longitudinal, multilevel analysis

BACKGROUND

Biologically plausible mechanisms link traffic-related air pollution to metabolic disorders and potentially to obesity. Here we sought to determine whether traffic density and traffic-related air pollution were positively associated with growth in body mass index (BMI = kg/m2) in children aged 5-11 years.

METHODS

Participants were drawn from a prospective cohort of children who lived in 13 communities across Southern California (N = 4550). Children were enrolled while attending kindergarten and first grade and followed for 4 years, with height and weight measured annually. Dispersion models were used to estimate exposure to traffic-related air pollution. Multilevel models were used to estimate and test traffic density and traffic pollution related to BMI growth. Data were collected between 2002-2010 and analyzed in 2011-12.

RESULTS

Traffic pollution was positively associated with growth in BMI and was robust to adjustment for many confounders. The effect size in the adjusted model indicated about a 13.6% increase in annual BMI growth when comparing the lowest to the highest tenth percentile of air pollution exposure, which resulted in an increase of nearly 0.4 BMI units on attained BMI at age 10. Traffic density also had a positive association with BMI growth, but this effect was less robust in multivariate models.

CONCLUSIONS

Traffic pollution was positively associated with growth in BMI in children aged 5-11 years. Traffic pollution may be controlled via emission restrictions; changes in land use that promote jobs-housing balance and use of public transit and hence reduce vehicle miles traveled; promotion of zero emissions vehicles; transit and car-sharing programs; or by limiting high pollution traffic, such as diesel trucks, from residential areas or places where children play outdoors, such as schools and parks. These measures may have beneficial effects in terms of reduced obesity formation in children.

Air pollution and hospital admissions for ischemic heart disease in persons with congestive heart failure or arrhythmia

We examined whether ischemic heart disease (IHD) hospital admissions were associated with air pollutants in those with and without secondary diagnoses of arrhythmia (ARR) or congestive heart failure (CHF). We assessed the occurrence of increased vulnerability among persons with these conditions to daily variations in ozone, carbon monoxide, nitrogen dioxide, or particulate matter less than or equal to 10 micro m in aerodynamic diameter (PM10). The study population consisted of members of a large health maintenance organization residing in the South Coast Air Basin of California from 1988 to 1995. After adjustment for day of week, study year, and smoothing splines for day of study, temperature, and relative humidity, CO and NO2 were both associated with admissions with the greatest effects for CO. A 1-ppm increase in 8-hr average CO was associated with a 3.60% [95% confidence interval (CI), 1.62-5.63%] increase in same-day IHD admissions in persons with a secondary diagnosis of CHF, a 2.99% (95% CI, 1.80-4.19%) increase in persons with a secondary diagnosis of ARR, and a 1.62% (95% CI, 0.65-2.59%) increase in IHD admissions in persons without either secondary diagnosis. Air pollution was most strongly associated with myocardial infarction hospital admissions. The vulnerability of the secondary CHF subgroup may be due to a greater prevalence of myocardial infarction primary diagnoses and not the modifying effect of CHF. This study suggests that people with IHD and accompanying CHF and/or ARR constitute a sensitive subgroup in relation to the effects of criteria ambient air pollutants associated with motor vehicle combustion.

Ambient Air Pollutants Have Adverse Effects on Insulin and Glucose Homeostasis in Mexican Americans

OBJECTIVE

Recent studies suggest that air pollution plays a role in type 2 diabetes (T2D) incidence and mortality. The underlying physiological mechanisms have yet to be established. We hypothesized that air pollution adversely affects insulin sensitivity and secretion and serum lipid levels.

RESEARCH DESIGN AND METHODS

Participants were selected from BetaGene (n = 1,023), a study of insulin resistance and pancreatic β-cell function in Mexican Americans. All participants underwent DXA and oral and intravenous glucose tolerance tests and completed dietary and physical activity questionnaires. Ambient air pollutant concentrations (NO2, O3, and PM2.5) for short- and long-term periods were assigned by spatial interpolation (maximum interpolation radius of 50 km) of data from air quality monitors. Traffic-related air pollution from freeways (TRAP) was estimated using the dispersion model as NOx. Variance component models were used to analyze individual and multiple air pollutant associations with metabolic traits.

RESULTS

Short-term (up to 58 days cumulative lagged averages) exposure to PM2.5 was associated with lower insulin sensitivity and HDL-to-LDL cholesterol ratio and higher fasting glucose and insulin, HOMA-IR, total cholesterol, and LDL cholesterol (LDL-C) (all P ≤ 0.036). Annual average PM2.5 was associated with higher fasting glucose, HOMA-IR, and LDL-C (P ≤ 0.043). The effects of short-term PM2.5 exposure on insulin sensitivity were largest among obese participants. No statistically significant associations were found between TRAP and metabolic outcomes.

CONCLUSIONS

Exposure to ambient air pollutants adversely affects glucose tolerance, insulin sensitivity, and blood lipid concentrations. Our findings suggest that ambient air pollutants may contribute to the pathophysiology in the development of T2D and related sequelae.

Health effects of the 2003 Southern California wildfires on children

RATIONALE

In late October 2003, Southern California wildfires burned more than 3,000 km2. The wildfires produced heavy smoke that affected several communities participating in the University of Southern California Children's Health Study (CHS).

OBJECTIVES

To study the acute effects of fire smoke on the health of CHS participants.

METHODS

A questionnaire was used to assess smoke exposure and occurrence of symptoms among CHS high-school students (n = 873; age, 17-18 yr) and elementary-school children (n = 5,551; age, 6-7 yr), in a total of 16 communities. Estimates of particulate matter (PM10) concentrations during the 5 d with the highest fire activity were used to characterize community smoke level.

MAIN RESULTS

All symptoms (nose, eyes, and throat irritations; cough; bronchitis; cold; wheezing; asthma attacks), medication usage, and physician visits were associated with individually reported exposure differences within communities. Risks increased monotonically with the number of reported smoky days. For most outcomes, reporting rates between communities were also associated with the fire-related PM10 levels. Associations tended to be strongest among those without asthma. Individuals with asthma were more likely to take preventive action, such as wearing masks or staying indoors during the fire.

CONCLUSIONS

Exposure to wildfire smoke was associated with increased eye and respiratory symptoms, medication use, and physician visits.

Prospective study of air pollution and bronchitic symptoms in children with asthma

The relationship of bronchitic symptoms to ambient particulate matter and to particulate elemental and organic carbon (OC), nitrogen dioxide (NO2), and other gaseous pollutants was examined in a cohort of children with asthma in 12 Southern California communities. Symptoms, assessed yearly by questionnaire from 1996 to 1999, were associated with the yearly variability of particulate matter with aerodynamic diameter less than 2.5 microg (odds ratio [OR] 1.09/microg/m3; 95% confidence interval [CI] 1.01-1.17), OC (OR 1.41/microg/m3; 95% CI 1.12-1.78), NO2 (OR 1.07/ppb; 95% CI 1.02-1.13), and ozone (OR 1.06/ppb; 95% CI 1.00-1.12). The ORs associated with yearly within-community variability in air pollution were larger than the effect of the between-community 4-year average concentrations. In two pollutant models, the effects of yearly variation in OC and NO2 were only modestly reduced by adjusting for other pollutants, except in a model containing both OC and NO2; the effects of all other pollutants were reduced after adjusting for OC or NO2. We conclude that OC and NO2 deserve greater attention as potential causes of the chronic symptoms of bronchitis in children with asthma and that previous cross-sectional studies may have underestimated the risks associated with air pollution.

Childhood obesity and asthma control in the GALA II and SAGE II studies

RATIONALE

Obesity is associated with increased asthma morbidity, lower drug responsiveness to inhaled corticosteroids, and worse asthma control. However, most prior investigations on obesity and asthma control have not focused on pediatric populations, considered environmental exposures, or included minority children.

OBJECTIVES

To examine the association between body mass index categories and asthma control among boys and girls; and whether these associations are modified by age and race/ethnicity.

METHODS

Children and adolescents ages 8-19 years (n = 2,174) with asthma were recruited from the Genes-environments and Admixture in Latino Americans (GALA II) Study and the Study of African Americans, Asthma, Genes, and Environments (SAGE II). Ordinal logistic regression was used to estimate odds ratios (OR) and their confidence intervals (95% CI) for worse asthma control.

MEASUREMENTS AND MAIN RESULTS

In adjusted analyses, boys who were obese had a 33% greater chance of having worse asthma control than their normal-weight counterparts (OR, 1.33; 95% CI, 1.04-1.71). However, for girls this association varied with race and ethnicity (P interaction = 0.008). When compared with their normal-weight counterparts, obese African American girls (OR, 0.65; 95% CI, 0.41-1.05) were more likely to have better controlled asthma, whereas Mexican American girls had a 1.91 (95% CI, 1.12-3.28) greater odds of worse asthma control.

CONCLUSIONS

Worse asthma control is uniformly associated with increased body mass index in boys. Among girls, the direction of this association varied with race/ethnicity.

Associations of air pollution, obesity and cardiometabolic health in young adults: The Meta-AIR study

OBJECTIVE

Growing evidence indicates exposure to air pollution contributes to obesity and cardiometabolic disease risk in children and adults, however studies are lacking in young adulthood, an important transitional period in the life course. The aim of this study was to examine the associations of short- and long-term regional ambient and near-roadway air pollution (NRAP) exposures on adiposity and cardiometabolic health in young adults aged 17-22 years.

METHODS

From 2014 to 2018, a subset of participants (n = 158) were recruited from the Children's Health Study to participate in the Meta-AIR (Metabolic and Asthma Incidence Research) study to assess obesity (body composition and abdominal adiposity) and cardiometabolic health (fasting glucose, fasting insulin and lipid profiles) measures. Prior 1-month and 1-year average air pollution exposures were calculated from residential addresses. This included nitrogen dioxide (NO₂), ozone (O₃), particulate matter with aerodynamic diameter < 10 μm (PM₁₀), particulate matter with aerodynamic diameter < 2.5 μm (PM_2.5) and NRAP (freeway, non-freeway, and total nitrogen oxides (NO_x)) exposures. Linear regression models examined associations of prior 1-month (short-term) and 1-year (long-term) air pollution exposures on obesity and cardiometabolic factors adjusting for covariates and past childhood air pollution exposures.

RESULTS

In the Meta-AIR study, we conducted a comprehensive analysis with short- and long-term regional ambient and NRAP exposures (in both single- and multi-pollutant models) and obesity- and cardiometabolic-related outcomes and found associations with a few outcomes. A 1 standard deviation (SD) change in long-term NO₂ exposure was associated with a 11.3 mg/dL higher level of total cholesterol (p = 0.04) and 9.4 mg/dL higher level of low-density lipoproteins (LDL)-cholesterol (p = 0.04). Amongst obese participants, associations between long-term NO₂ and total cholesterol and LDL-cholesterol were 4.5 and 9 times larger than the associations in non-obese participants (p_interaction = 0.008 and 0.03, respectively). Additionally, we observed a statistically significant association with increased short-term O₃ exposure and higher triglyceride and very-low-density lipoprotein (VLDL) cholesterol levels (p = 0.04), lower high-density lipoprotein (HDL) cholesterol levels (p = 0.03), and higher hepatic fat levels (p = 0.02). Amongst glucose-related factors, long-term PM_2.5 exposure was associated with higher levels of insulin area under the curve (p = 0.03). There were no other statistically significant associations with short- or long-term air pollutants and BMI, other measures of adiposity, and cardiometabolic outcomes.

CONCLUSION

Higher exposure to regional air pollutants, namely prior 1-year average NO₂, was associated with higher fasting serum lipid measures. These associations were more pronounced in obese participants, suggesting obesity may exacerbate the effects of air pollution exposure on lipid levels in young adults. This study did not find any other associations between short- and long-term ambient and NRAP exposures across a range of other obesity and cardiometabolic indicators. Further studies in young adults are warranted as our study suggests potential deleterious associations of both short- and long-term air pollution exposures and lipid metabolism.

Genetic ancestry influences asthma susceptibility and lung function among Latinos

BACKGROUND

Childhood asthma prevalence and morbidity varies among Latinos in the United States, with Puerto Ricans having the highest and Mexicans the lowest.

OBJECTIVE

To determine whether genetic ancestry is associated with the odds of asthma among Latinos, and secondarily whether genetic ancestry is associated with lung function among Latino children.

METHODS

We analyzed 5493 Latinos with and without asthma from 3 independent studies. For each participant, we estimated the proportion of African, European, and Native American ancestry using genome-wide data. We tested whether genetic ancestry was associated with the presence of asthma and lung function among subjects with and without asthma. Odds ratios (OR) and effect sizes were assessed for every 20% increase in each ancestry.

RESULTS

Native American ancestry was associated with lower odds of asthma (OR = 0.72, 95% CI: 0.66-0.78, P = 8.0 × 10(-15)), while African ancestry was associated with higher odds of asthma (OR = 1.40, 95% CI: 1.14-1.72, P = .001). These associations were robust to adjustment for covariates related to early life exposures, air pollution, and socioeconomic status. Among children with asthma, African ancestry was associated with lower lung function, including both pre- and post-bronchodilator measures of FEV1 (-77 ± 19 mL; P = 5.8 × 10(-5) and -83 ± 19 mL; P = 1.1 x 10(-5), respectively) and forced vital capacity (-100 ± 21 mL; P = 2.7 × 10(-6) and -107 ± 22 mL; P = 1.0 x 10(-6), respectively).

CONCLUSION

Differences in the proportions of genetic ancestry can partially explain disparities in asthma susceptibility and lung function among Latinos.

Traffic exposure and lung function in adults: the Atherosclerosis Risk in Communities study

BACKGROUND

Traffic exposure is a major contributor to ambient air pollution for people living close to busy roads. The relationship between traffic exposure and lung function remains inconclusive in adults.

METHODS

A cross-sectional study was conducted to investigate the association between traffic exposure and lung function in the Atherosclerosis Risk in Communities (ARIC) study, a community based cohort of 15 792 middle aged men and women. Traffic density and distance to major roads were used as measures of traffic exposure.

RESULTS

After controlling for potential confounders including demographic factors, personal and neighbourhood level socioeconomic characteristics, cigarette smoking and background air pollution, higher traffic density was significantly associated with lower forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) in women. Relative to the lowest quartile of traffic density, the adjusted differences across increasing quartiles were 5.1, -15.4 and -21.5 ml for FEV1 (p value of linear trend across the quartiles = 0.041) and 1.2, -23.4 and -34.8 ml for FVC (p trend = 0.010). Using distance from major roads as a simpler index of traffic related air pollution exposure, the FEV1 was -15.7 ml (95% CI -34.4 to 2.9) lower and the FVC was -24.2 ml (95% CI -46.2 to -2.3) lower for women living within 150 m compared with subjects living further away. There was no significant effect of traffic density or distance to major roads on lung function in men. The FEV1/FVC ratio was not significantly associated with traffic exposure in either men or women.

CONCLUSIONS

This is the largest published study of traffic exposure and pulmonary function in adults to date. These results add to growing evidence that chronic exposure to traffic related air pollution may adversely affect respiratory health.

A genome-wide association study of bronchodilator response in Latinos implicates rare variants

BACKGROUND

The primary rescue medication to treat acute asthma exacerbation is the short-acting β₂-adrenergic receptor agonist; however, there is variation in how well a patient responds to treatment. Although these differences might be due to environmental factors, there is mounting evidence for a genetic contribution to variability in bronchodilator response (BDR).

OBJECTIVE

To identify genetic variation associated with bronchodilator drug response in Latino children with asthma.

METHODS

We performed a genome-wide association study (GWAS) for BDR in 1782 Latino children with asthma using standard linear regression, adjusting for genetic ancestry and ethnicity, and performed replication studies in an additional 531 Latinos. We also performed admixture mapping across the genome by testing for an association between local European, African, and Native American ancestry and BDR, adjusting for genomic ancestry and ethnicity.

RESULTS

We identified 7 genetic variants associated with BDR at a genome-wide significant threshold (P < 5 × 10(-8)), all of which had frequencies of less than 5%. Furthermore, we observed an excess of small P values driven by rare variants (frequency, <5%) and by variants in the proximity of solute carrier (SLC) genes. Admixture mapping identified 5 significant peaks; fine mapping within these peaks identified 2 rare variants in SLC22A15 as being associated with increased BDR in Mexicans. Quantitative PCR and immunohistochemistry identified SLC22A15 as being expressed in the lung and bronchial epithelial cells.

CONCLUSION

Our results suggest that rare variation contributes to individual differences in response to albuterol in Latinos, notably in SLC genes that include membrane transport proteins involved in the transport of endogenous metabolites and xenobiotics. Resequencing in larger, multiethnic population samples and additional functional studies are required to further understand the role of rare variation in BDR.