Work Disability Duration Among Mobile Workers: Does Intraprovincial Mobility Matter as Much as Interprovincial Mobility?

OBJECTIVE: The aim of the study is to compare work disability duration of intraprovincially and interprovincially mobile workers with nonmobile workers in British Columbia, Canada. METHODS: Workers' compensation claims were extracted for workers injured between 2010 and 2019. Employer and residential postal codes were converted to economic regions to define nonmobile, intraprovincially, and interprovincially mobile workers. Quantile regression models using matched cohorts were used to estimate differences in work disability days at different percentiles of the distribution. RESULTS: Compared with nonmobile workers, both mobile worker groups had longer work disability durations, particularly interprovincially mobile workers. Differences persisted in injury-stratified models and were partially or fully attenuated in some industry-stratified models. CONCLUSIONS: Workers' compensation systems, employers, and healthcare providers may need to tailor specific interventions for mobile workers who are from out-of-province as well as traveling between regions in the province.

Heat-Related Illness Among Workers in British Columbia, 2001-2020.

OBJECTIVE: The aim of this study was to describe the incidence of heat-related illness among workers in British Columbia (BC), Canada, 2001-2020. METHODS: Cases of heat-related illness occurring among workers aged 15 years and older were identified from accepted lost-time claims from WorkSafeBC, the provincial workers' compensation board. Incidence rates were calculated using monthly estimates of the working population from Statistics Canada's Labour Force Survey as the denominator. RESULTS: Between 2000 and 2020, there were 528 heat-related illness claims, corresponding to a rate of 1.21 (95% confidence interval, 1.10-1.31) claims per 100,000 workers. Eighty-four percent of claims occurred between June and August. Rates were higher among male workers, younger workers, and among those working in occupations related to primary industry; trades, transport, and equipment operators; and processing, manufacturing, and utilities. CONCLUSIONS: In BC, lost-time claims for heat-related illness occurred disproportionately among certain subgroups of the workforce.

Do patterns of past asbestos use and production reflect current geographic variations of cancer risk?: mesothelioma in Ontario and British Columbia, Canada.

PURPOSE: Canada was a major global asbestos producer and consumer. Geographic patterns of Canadian asbestos use and mesothelioma, a highly fatal cancer linked to asbestos exposure, have not been previously reported. This study summarized key trends in mesothelioma incidence by geography and time in two Canadian provinces, Ontario and British Columbia (BC), and explored how past workforce characteristics and geographic trends in asbestos production and use may shape variations in regional rates of mesothelioma. METHODS: We report trends in mesothelioma incidence (1993-2016) for Ontario and British Columbia using population-based incidence data that were age-standardized to the 2011 Canadian population. Historical records of asbestos production and use were analyzed to geo-locate industrial point sources of asbestos in Ontario and BC. The prevalence of occupations in regions with the highest and lowest rates of mesothelioma in Ontario and BC were calculated using labor force statistics from the 1981 Canadian Census. RESULTS: Regional mesothelioma rates varied in both provinces over time; more census divisions in both Ontario and BC registered mesothelioma rates in the highest quintile of incidences during the period 2009 to 2016 than in any prior period examined. Certain occupations such as construction trades workers were more likely to be overrepresented in regions with high mesothelioma rates. CONCLUSION: This work explored how studying asbestos exposure and mesothelioma incidence at small-scale geographies could direct cancer surveillance and research to more targeted areas. Findings indicated that regional variations in mesothelioma could signal important differences in past occupational and potentially environmental exposures.

Differences in Modified-Return-to-Work by Immigration Characteristics Among a Cohort of Workers in British Columbia, Canada.

Introduction To investigate differences in modified-return-to work (MRTW) within the first 30 days of a work-related, short-term disability injury by immigration characteristics. This question was part of a program of research investigating differences in work and health experiences among immigrant workers and explanations for longer work disability durations. Methods Workers' compensation claims, immigration records and medical registry data were linked to identify a sample of workers in British Columbia, Canada with a short-term disability claim for a work-related back strain, concussion, limb fracture or connective tissue injury occurring between 2009 and 2015. Multivariable logistic regressions, stratified by injury type, investigated the odds of MRTW, defined as at least one day within the first 30 days on claim, associated with immigration characteristics, defined as a Canadian-born worker versus a worker who immigrated via the economic, family member or refugee/other humanitarian classification. Results Immigrant workers who arrived to Canada as a family member or as a refugee/other immigrant had a reduced odds of MRTW within the first 30 days of work disability for a back strain, concussion and limb fracture, compared to Canadian-born workers. Differences in MRTW were not observed for immigrant workers who arrived to Canada via the economic classification, or for connective tissue injuries. Conclusion The persistent and consistent finding of reduced MRTW for the same injury for different immigration classifications highlights contexts (work, health, social, language) that disadvantage some immigrants upon arrival to Canada and that persist over time even after entry into the workforce, including barriers to MRTW.

Differences in Work Disability Duration for Immigrants and Canadian-Born Workers in British Columbia, Canada.

This study aimed to investigate differences in work disability duration among immigrants (categorized as economic, family member or refugee/other classification upon arrival to Canada) compared to Canadian-born workers with a work-related injury in British Columbia. Immigrants and Canadian-born workers were identified from linked immigration records with workers' compensation claims for work-related back strain, connective tissue, concussion and fracture injuries requiring at least one paid day of work disability benefits between 2009 to 2015. Quantile regression investigated the relationship between immigration classification and predicted work disability days (defined from injury date to end of compensation claim, up to 365 days) and modeled at the 25th, 50th and 75th percentile of the distribution of the disability days. With a few exceptions, immigrants experienced greater predicted disability days compared to Canadian-born workers within the same injury cohort. The largest differences were observed for family and refugee/other immigrant classification workers, and, in particular, for women within these classifications, compared to Canadian-born workers. For example, at the 50th percentile of the distribution of disability days, we observed a difference of 34.1 days longer for refugee/other women in the concussion cohort and a difference of 27.5 days longer for family classification women in the fracture cohort. Economic immigrants had comparable disability days with Canadian-born workers, especially at the 25th and 50th percentiles of the distribution. Immigrant workers' longer disability durations may be a result of more severe injuries or challenges navigating the workers' compensation system with delays in seeking disability benefits and rehabilitation services. Differences by immigrant classification speak to vulnerabilities or inequities upon arrival in Canada that persist after entry to the workforce and warrant further investigation for early mitigation strategies.

Road proximity, air pollution, noise, green space and neurologic disease incidence: a population-based cohort study.

BACKGROUND: Emerging evidence links road proximity and air pollution with cognitive impairment. Joint effects of noise and greenness have not been evaluated. We investigated associations between road proximity and exposures to air pollution, and joint effects of noise and greenness, on non-Alzheimer's dementia, Parkinson's and Alzheimer's disease and multiple sclerosis within a population-based cohort. METHODS: We assembled administrative health database cohorts of 45-84 year old residents (N ~ 678,000) of Metro Vancouver, Canada. Cox proportional hazards models were built to assess associations between exposures and non-Alzheimer's dementia and Parkinson's disease. Given reduced case numbers, associations with Alzheimer's disease and multiple sclerosis were evaluated in nested case-control analyses by conditional logistic regression. RESULTS: Road proximity was associated with all outcomes (e.g. non-Alzheimer's dementia hazard ratio: 1.14, [95% confidence interval: 1.07-1.20], for living < 50 m from a major road or < 150 m from a highway). Air pollutants were associated with incidence of Parkinson's disease and non-Alzheimer's dementia (e.g. Parkinson's disease hazard ratios of 1.09 [1.02-1.16], 1.03 [0.97-1.08], 1.12 [1.05-1.20] per interquartile increase in fine particulate matter, Black Carbon, and nitrogen dioxide) but not Alzheimer's disease or multiple sclerosis. Noise was not associated with any outcomes while associations with greenness suggested protective effects for Parkinson's disease and non-Alzheimer's dementia. CONCLUSIONS: Road proximity was associated with incidence of non-Alzheimer's dementia, Parkinson's disease, Alzheimer's disease and multiple sclerosis. This association may be partially mediated by air pollution, whereas noise exposure did not affect associations. There was some evidence of protective effects of greenness.

Association of Long-Term Exposure to Transportation Noise and Traffic-Related Air Pollution with the Incidence of Diabetes: A Prospective Cohort Study.

BACKGROUND: Evidence for an association between transportation noise and cardiovascular disease has increased; however, few studies have examined metabolic outcomes such as diabetes or accounted for environmental coexposures such as air pollution, greenness, or walkability. OBJECTIVES: Because diabetes prevalence is increasing and may be on the causal pathway between noise and cardiovascular disease, we examined the influence of long-term residential transportation noise exposure and traffic-related air pollution on the incidence of diabetes using a population-based cohort in British Columbia, Canada. METHODS: We examined the influence of transportation noise exposure over a 5-y period (1994-1998) on incident diabetes cases in a population-based prospective cohort study (n=380,738) of metropolitan Vancouver (BC) residents who were 45-85 y old, with 4-y of follow-up (1999-2002). Annual average transportation noise (Lden), air pollution [black carbon, particulate matter with aerodynamic diameter <2.5µm (PM2.5), nitrogen oxides], greenness [Normalized Difference Vegetation Index (NDVI)], and neighborhood walkability at each participant's residence were modeled. Incident diabetes cases were identified using administrative health records. RESULTS: Transportation noise was associated with the incidence of diabetes [interquartile range (IQR) increase, 6.8 A-weighted decibels (dBA); OR=1.08 (95% CI: 1.05, 1.10)]. This association remained after adjustment for environmental coexposures including traffic-related air pollutants, greenness, and neighborhood walkability. After adjustment for coexposure to noise, traffic-related air pollutants were not associated with the incidence of diabetes, whereas greenness was protective. CONCLUSION: We found a positive association between residential transportation noise and diabetes, adding to the growing body of evidence that noise pollution exposure may be independently linked to metabolic health and should be considered when developing public health interventions. https://doi.org/10.1289/EHP1279.

Asthma Trajectories in a Population-based Birth Cohort. Impacts of Air Pollution and Greenness.

RATIONALE: The heterogeneity of asthma phenotypes may explain inconsistencies in observed associations with environmental exposures. OBJECTIVES: To identify trajectories of childhood asthma and to characterize the potential impact of residential greenness and air pollution on asthma trajectory subgroups. METHODS: Linked administrative databases of medical visits were used to define the occurrence and recurrence of asthma over a 10-year follow-up period within a population-based birth cohort of more than 65,000 children. Group-based trajectory modeling was used to identify unique asthma trajectories. Weighted multinomial regression was used to assess the relationship between asthma trajectories and risk factors, including environmental exposures. MEASUREMENTS AND MAIN RESULTS: Group-based trajectory modeling distinguished four trajectories: one with no asthma representing 88.8% of the cohort, one with transient asthma (5.6% of the cohort), and two trajectories with chronic asthma with early (<1 yr; 1.5%) and late (<3 yr; 4.1%) onset during early childhood. These trajectories differed with respect to socioeconomic markers and modifiable risk factors, including maternal smoking and breastfeeding initiation. After accounting for sex, parity, breastfeeding, term birth weight, household income, maternal education, delivery mode, and smoking, an interquartile increase in nitrogen dioxide exposure increased the risk of membership in the early and late-onset chronic asthma trajectories, relative to subjects without asthma, by 50% and 20%, respectively (weighted risk ratio, 1.5 and 1.2; 95% confidence interval, 1.2-1.9 and 1.0-1.4). Greenness was not associated with any of the asthma trajectories. CONCLUSIONS: Traffic-related air pollution increased the probability of a chronic asthma trajectory.

Perinatal air pollution exposure and development of asthma from birth to age 10 years.

Within-city variation in air pollution has been associated with childhood asthma development, but findings have been inconsistent. We examined whether perinatal air pollution exposure affected asthma onset during "pre-school and "school age" periods in a population-based birth cohort.65,254 children born between 1999 and 2002 in the greater Vancouver metropolitan region were followed until age 10 years using linked administrative health databases. Asthma cases were sex- and age-matched to five randomly chosen controls. Associations between exposure to air pollutants estimated with different methods (interpolation (inverse-distance weighted (IDW)), land use regression, proximity) and incident asthma during the pre-school (0-5 years) and school age (6-10 years) periods were estimated with conditional logistic regression.6948 and 1711 cases were identified during the pre-school and school age periods, respectively. Following adjustment for birthweight, gestational period, household income, parity, breastfeeding at discharge, maternal age and education, asthma risk during the pre-school years was increased by traffic pollution (adjusted odds ratio using IDW method per interquartile increase (95% CI): nitric oxide 1.06 (1.01-1.11), nitrogen dioxide 1.09 (1.04-1.13) and carbon monoxide 1.05 (1.01-1.1)). Enhanced impacts were observed amongst low-term-birthweight cases. Associations were independent of surrounding residential greenness.Within-city air pollution variation was associated with new asthma onset during the pre-school years.

Residential greenness and birth outcomes: evaluating the influence of spatially correlated built-environment factors.

BACKGROUND: Half the world's population lives in urban areas. It is therefore important to identify characteristics of the built environment that are beneficial to human health. Urban greenness has been associated with improvements in a diverse range of health conditions, including birth outcomes; however, few studies have attempted to distinguish potential effects of greenness from those of other spatially correlated exposures related to the built environment. OBJECTIVES: We aimed to investigate associations between residential greenness and birth outcomes and evaluate the influence of spatially correlated built environment factors on these associations. METHODS: We examined associations between residential greenness [measured using satellite-derived Normalized Difference Vegetation Index (NDVI) within 100 m of study participants' homes] and birth outcomes in a cohort of 64,705 singleton births (from 1999-2002) in Vancouver, British Columbia, Canada. We also evaluated associations after adjusting for spatially correlated built environmental factors that may influence birth outcomes, including exposure to air pollution and noise, neighborhood walkability, and distance to the nearest park. RESULTS: An interquartile increase in greenness (0.1 in residential NDVI) was associated with higher term birth weight (20.6 g; 95% CI: 16.5, 24.7) and decreases in the likelihood of small for gestational age, very preterm (< 30 weeks), and moderately preterm (30-36 weeks) birth. Associations were robust to adjustment for air pollution and noise exposures, neighborhood walkability, and park proximity. CONCLUSIONS: Increased residential greenness was associated with beneficial birth outcomes in this population-based cohort. These associations did not change after adjusting for other spatially correlated built environment factors, suggesting that alternative pathways (e.g., psychosocial and psychological mechanisms) may underlie associations between residential greenness and birth outcomes.

Proximity to traffic, ambient air pollution, and community noise in relation to incident rheumatoid arthritis.

BACKGROUND: The risk of rheumatoid arthritis (RA) has been associated with living near traffic; however, there is evidence suggesting that air pollution may not be responsible for this association. Noise, another traffic-generated exposure, has not been studied as a risk factor for RA. OBJECTIVES: We investigated proximity to traffic, ambient air pollution, and community noise in relation to RA in the Vancouver and Victoria regions of British Columbia, Canada. METHODS: Cases and controls were identified in a cohort of adults that was assembled using health insurance registration records. Incident RA cases from 1999 through 2002 were identified by diagnostic codes in combination with prescriptions and type of physician (e.g., rheumatologist). Controls were matched to RA cases by age and sex. Environmental exposures were assigned to each member of the study population by their residential postal code(s). We estimated relative risks using conditional logistic regression, with additional adjustment for median income at the postal code. RESULTS: RA incidence was increased with proximity to traffic, with an odds ratio (OR) of 1.37 (95% CI: 1.11, 1.68) for residence ≤ 50 m from a highway compared with residence > 150 m away. We found no association with traffic-related exposures such as PM2.5, nitrogen oxides, or noise. Ground-level ozone, which was highest in suburban areas, was associated with an increased risk of RA (OR = 1.26; 95% CI: 1.18, 1.36 per interquartile range increase). CONCLUSIONS: Our study confirms a previously observed association of RA risk with proximity to traffic and suggests that neither noise levels nor traffic-related air pollutants are responsible for this relationship. Additional investigation of neighborhood and individual correlates of residence near roadways may provide new insight into risk factors for RA.

Impact of noise and air pollution on pregnancy outcomes.

BACKGROUND: Motorized traffic is an important source of both air pollution and community noise. While there is growing evidence for an adverse effect of ambient air pollution on reproductive health, little is known about the association between traffic noise and pregnancy outcomes. METHODS: We evaluated the impact of residential noise exposure on small size for gestational age, preterm birth, term birth weight, and low birth weight at term in a population-based cohort study, for which we previously reported associations between air pollution and pregnancy outcomes. We also evaluated potential confounding of air pollution effects by noise and vice versa. Linked administrative health data sets were used to identify 68,238 singleton births (1999-2002) in Vancouver, British Columbia, Canada, with complete covariate data (sex, ethnicity, parity, birth month and year, income, and education) and maternal residential history. We estimated exposure to noise with a deterministic model (CadnaA) and exposure to air pollution using temporally adjusted land-use regression models and inverse distance weighting of stationary monitors for the entire pregnancy. RESULTS: Noise exposure was negatively associated with term birth weight (mean difference = -19 [95% confidence interval = -23 to -15] g per 6 dB(A)). In joint air pollution-noise models, associations between noise and term birth weight remained largely unchanged, whereas associations decreased for all air pollutants. CONCLUSION: Traffic may affect birth weight through exposure to both air pollution and noise.

Maternal exposure to particulate air pollution and term birth weight: a multi-country evaluation of effect and heterogeneity.

BACKGROUND: A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent. OBJECTIVES: We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association. METHODS: Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM(10) and PM(2.5) (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates. RESULTS: In random-effects meta-analyses, term LBW was positively associated with a 10-µg/m3 increase in PM10 [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM(2.5) (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-µg/m3 increase in PM(10) exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (-8.9 g; 95% CI: -13.2, -4.6 g). Meta-regressions revealed that centers with higher median PM(2.5) levels and PM(2.5):PM(10) ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations. CONCLUSION: Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.

The International Collaboration on Air Pollution and Pregnancy Outcomes: initial results.

BACKGROUND: The findings of prior studies of air pollution effects on adverse birth outcomes are difficult to synthesize because of differences in study design. OBJECTIVES: The International Collaboration on Air Pollution and Pregnancy Outcomes was formed to understand how differences in research methods contribute to variations in findings. We initiated a feasibility study to a) assess the ability of geographically diverse research groups to analyze their data sets using a common protocol and b) perform location-specific analyses of air pollution effects on birth weight using a standardized statistical approach. METHODS: Fourteen research groups from nine countries participated. We developed a protocol to estimate odds ratios (ORs) for the association between particulate matter ≤ 10 µm in aerodynamic diameter (PM10) and low birth weight (LBW) among term births, adjusted first for socioeconomic status (SES) and second for additional location-specific variables. RESULTS: Among locations with data for the PM10 analysis, ORs estimating the relative risk of term LBW associated with a 10-µg/m³ increase in average PM10 concentration during pregnancy, adjusted for SES, ranged from 0.63 [95% confidence interval (CI), 0.30-1.35] for the Netherlands to 1.15 (95% CI, 0.61-2.18) for Vancouver, with six research groups reporting statistically significant adverse associations. We found evidence of statistically significant heterogeneity in estimated effects among locations. CONCLUSIONS: Variability in PM10-LBW relationships among study locations remained despite use of a common statistical approach. A more detailed meta-analysis and use of more complex protocols for future analysis may uncover reasons for heterogeneity across locations. However, our findings confirm the potential for a diverse group of researchers to analyze their data in a standardized way to improve understanding of air pollution effects on birth outcomes.

Residential air pollution and otitis media during the first two years of life.

BACKGROUND: : Otitis media is the leading reason young children receive antibiotics or visit a physician. We evaluated the impact of ambient air pollution on outpatient physician visits for otitis media in a population-based birth cohort. METHODS: : All children born in southwestern British Columbia during 1999-2000 were followed until the age of 2 years. Residential air pollution exposures were estimated for the first 24 months of life by inverse-distance weighting of monitor data (CO, NO, NO2, O3, PM2.5, PM10, SO2), temporally adjusted land-use regression models (NO, NO2, PM2.5, black carbon, woodsmoke), and proximity to roads and point sources. We used generalized estimating equations to longitudinally assess the relationship between physician visits for otitis media (ICD-9) and average pollutant exposure in the 2 months prior to the visit, after adjustment for covariates. RESULTS: : Complete exposure and risk-factor data were available for 45,513 children (76% of all births). A total of 42% of subjects had 1 or more physician visits for otitis media during follow-up. Adjusted estimates for NO, PM2.5, and woodsmoke were consistently elevated (eg, relative risk of 1.10 [95% confidence interval = 1.07-1.12] per interquartile range [IQR] increase in NO; 1.32 [1.27-1.36] per IQR increase in days of woodsmoke exposure). No increased risks were observed for the remaining pollutants (eg, 1.00 [0.98-1.03] per IQR increase in PM10; 0.99 [0.97-1.01] per IQR increase in black carbon). CONCLUSIONS: : Modest but consistent associations were found between some measures of air pollution and otitis media in a large birth cohort exposed to relatively low levels of ambient air pollution.

Long-term exposure to traffic-related air pollution and the risk of coronary heart disease hospitalization and mortality.

BACKGROUND: Epidemiologic studies have demonstrated that exposure to road traffic is associated with adverse cardiovascular outcomes. OBJECTIVES: We aimed to identify specific traffic-related air pollutants that are associated with the risk of coronary heart disease (CHD) morbidity and mortality to support evidence-based environmental policy making. METHODS: This population-based cohort study included a 5-year exposure period and a 4-year follow-up period. All residents 45-85 years of age who resided in Metropolitan Vancouver during the exposure period and without known CHD at baseline were included in this study (n=452,735). Individual exposures to traffic-related air pollutants including black carbon, fine particles [aerodynamic diameter ≤ 2.5 µm (PM(2.5))], nitrogen dioxide (NO(2)), and nitric oxide were estimated at residences of the subjects using land-use regression models and integrating changes in residences during the exposure period. CHD hospitalizations and deaths during the follow-up period were identified from provincial hospitalization and death registration records. RESULTS: An interquartile range elevation in the average concentration of black carbon (0.94 × 10(-5)/m filter absorbance, equivalent to approximately 0.8 µg/m(3) elemental carbon) was associated with a 3% increase in CHD hospitalization (95% confidence interval, 1-5%) and a 6% increase in CHD mortality (3-9%) after adjusting for age, sex, preexisting comorbidity, neighborhood socioeconomic status, and copollutants (PM(2.5) and NO(2)). There were clear linear exposure-response relationships between black carbon and coronary events. CONCLUSIONS: Long-term exposure to traffic-related fine particulate air pollution, indicated by black carbon, may partly explain the observed associations between exposure to road traffic and adverse cardiovascular outcomes.

Changes in residential proximity to road traffic and the risk of death from coronary heart disease.

BACKGROUND: Residential proximity to road traffic is associated with increased coronary heart disease (CHD) morbidity and mortality. It is unknown, however, whether changes in residential proximity to traffic could alter the risk of CHD mortality. METHODS: We used a population-based cohort study with a 5-year exposure period and a 4-year follow-up period to explore the association between changes in residential proximity to road traffic and the risk of CHD mortality. The cohort comprised all residents aged 45-85 years who resided in metropolitan Vancouver during the exposure period and without known CHD at baseline (n = 450,283). Residential proximity to traffic was estimated using a geographic information system. CHD deaths during the follow-up period were identified using provincial death registration database. The data were analyzed using logistic regression. RESULTS: Compared with the subjects consistently living away from road traffic (>150 m from a highway or >50 m from a major road) during the 9-year study period, those consistently living close to traffic (

Effect of early life exposure to air pollution on development of childhood asthma.

BACKGROUND: There is increasing recognition of the importance of early environmental exposures in the development of childhood asthma. Outdoor air pollution is a recognized asthma trigger, but it is unclear whether exposure influences incident disease. We investigated the effect of exposure to ambient air pollution in utero and during the first year of life on risk of subsequent asthma diagnosis in a population-based nested case-control study. METHODS: We assessed all children born in southwestern British Columbia in 1999 and 2000 (n = 37,401) for incidence of asthma diagnosis up to 34 years of age using outpatient and hospitalization records. Asthma cases were age- and sex-matched to five randomly chosen controls from the eligible cohort. We estimated each individual's exposure to ambient air pollution for the gestational period and first year of life using high-resolution pollution surfaces derived from regulatory monitoring data as well as land use regression models adjusted for temporal variation. We used logistic regression analyses to estimate effects of carbon monoxide, nitric oxide, nitrogen dioxide, particulate matter

Otitis media incidence and risk factors in a population-based birth cohort.

BACKGROUND: Otitis media is the main reason young children receive antibiotics and is the leading reason for physician visits. OBJECTIVE: To characterize the incidence, recurrence and risk factors for otitis media in a population-based birth cohort. METHODS: All children born in southwestern British Columbia during 1999 to 2000 were followed until the age of three years. Otitis media was defined using The International Classification of Diseases, Ninth Revision coding of physician visits, and linked with antibiotic prescription data. Information on sex, birth weight, gestational age, Aboriginal status, maternal age, older siblings, maternal smoking during pregnancy, breastfeeding initiation, neighbourhood income, female education and rural residence were obtained from vital statistics, birth hospitalizations, perinatal registry and census data. RESULTS: Complete risk factor information was available for 50,474 children (86% of all births). Nearly one-half of the children (48.6%) had one or more physician visits for otitis media during follow-up, and 3952 children (7.8%) met the definition for recurrent otitis media. Of the children with at least three visits during follow-up (n=7571), 73% had their initial visit during the first year of life. Aboriginal status, maternal age younger than 20 years, male sex and older siblings were the strongest risk factors identified in the adjusted conditional logistic regression models. DISCUSSION: The present study established a population-based birth cohort by linking multiple administrative databases to characterize the incidence of and risk factors for otitis media. Although the incidence of otitis media is generally low in southwestern British Columbia, important risk factors continue to be young maternal age, mothers who smoke during pregnancy and children with Aboriginal ancestry.