Where should we go - Estimating travel times for modelling accessibility to 24-hour emergency departments in Canada.

Estimating travel time to 24-hour emergency services is an important component to modelling accessibility of health services, particularly for rural areas. However, methods used to estimate travel time vary significantly, are not representative of the residential population, and are not openly validated. This makes the assessment of travel-based accessibility metrics between studies incomparable. To address this issue and develop a standardized measurement of emergency service access, this study utilized small geographic units (Dissemination Areas - DA) and geographical boundaries representative of municipal equivalents (Census Subdivision - CSD). Estimated travel times between the centroid of an inhabited DA to each 24-hr emergency department was computed with population-weighted travel times generated for each CSD. This dataset provides a nationally consistent measurement of proximity to emergency services accounting for travel pathing and population distribution. This methodology can be extended to generate estimated shortest travel routes for other healthcare resources or develop actual travel routes based on individuals' experiences with the healthcare system.

Characteristics of High-Resource Health System Users in Rural and Remote Regions: A Scoping Review.

A small proportion of health care users are recognized to use a significantly higher proportion of health system resources, largely due to systemic, inequitable access and disproportionate health burdens. These high-resource health system users are routinely characterized as older, with multiple comorbidities, and reduced access to adequate health care. Geographic trends also emerge, with more rural and isolated regions demonstrating higher rates of high-resource use than others. Despite known geographical discrepancies in health care access and outcomes, health policy and research initiatives remain focused on urban population centers. To alleviate mounting health system pressure from high-resource users, their characteristics must be better understood within the context in which i arises. To examine this, a scoping review was conducted to provide an overview of characteristics of high-resource users in rural and remote communities in Canada and Australia. In total, 21 papers were included in the review. Using qualitative thematic coding, primary findings characterized rural high-resource users as those of an older age; with increased comorbid conditions and condition severity; lower socioeconomic status; and elevated risk behaviors.

Patient and provider perspectives on eHealth interventions in Canada and Australia: a scoping review.

INTRODUCTION: Despite the promises of universal health care in most developed countries, health inequities remain prevalent within and between rural and remote communities. Remote health technologies are often promoted as solutions to increase health system efficiency, to enhance quality of care, and to decrease gaps in access to care for rural and remote communities. However, there is mixed evidence for these interventions, particularly related to how they are received and perceived by health providers and by patients. Health technologies do not always adequately meet the needs of patients or providers. To examine this, a broad-based scoping review was conducted to provide an overview of patient and provider perspectives of eHealth initiatives in rural communities. The unique objective of this review was to prioritize the voices of patients and providers in discussing the disparities between health interventions and needs of people in rural communities. eHealth initiatives were reviewed for rural communities of Australia and Canada, two countries that have similar geographies and comparable health systems at the local level. METHODS: Searches were performed in PubMed, Scopus, and Web of Science with results limited from 2000 to 2018. Keywords included combinations of 'eHealth', 'telehealth', 'telemedicine', 'electronic health', and 'rural/remote'. Individual patient and provider perspectives on health care were identified, followed by qualitative thematic coding based on the type of intervention, the feedback provided, the affected population, geographic location, and category of individual providing their perspective. Quotes from patients and providers are used to illustrate the identified benefits and disadvantages of eHealth technologies. RESULTS: Based on reviewed literature, 90.1% of articles reported that eHealth interventions were largely positive. Articles noted decreased travel time (18%), time/cost saving (15.1%), and increased access to services (13.9%) as primary benefits to eHealth. The most prevalent disadvantages of eHealth were technological issues (24.5%), lack of face-to-face contact (18.6%), limited training (10.8%), and resource disparities (10.8%). These results show where existing eHealth interventions could improve and can inform policymakers and providers in designing new interventions. Importantly, benefits to eHealth extend beyond geographic access. Patients reported ancillary benefits to eHealth that include reduced anxiety, disruption on family life, and improved recovery time. Providers reported closer connections to colleagues, improved support for complex care, and greater eLearning opportunity. Barriers to eHealth are recognized by patient and providers alike to be largely systemic, where lack of rural high-speed internet and unreliability of installed technologies were significant. CONCLUSION: Regional and national governments are seen as the key players in addressing these technical barriers. This scoping review diverges from many reviews of eHealth with the use of first-person perspectives. It is hoped that this focus will highlight the importance of patient voices in evaluating important healthcare interventions such as eHealth and associated technologies.

Traffic-Related Air Pollution and Carotid Plaque Burden in a Canadian City With Low-Level Ambient Pollution.

Background The association between fine particulate matter and cardiovascular disease has been convincingly demonstrated. The role of traffic-related air pollutants is less clear. To better understand the role of traffic-related air pollutants in cardiovascular disease development, we examined associations between NO2, carotid atherosclerotic plaque, and cardiometabolic disorders associated with cardiovascular disease. Methods and Results Cross-sectional analyses were conducted among 2227 patients (62.9±13.8 years; 49.5% women) from the Stroke Prevention and Atherosclerosis Research Centre (SPARC) in London, Ontario, Canada. Total carotid plaque area measured by ultrasound, cardiometabolic disorders, and residential locations were provided by SPARC medical records. Long-term outdoor residential NO2 concentrations were generated by a land use regression model. Associations between NO2, total carotid plaque area, and cardiometabolic disorders were examined using multiple regression models adjusted for age, sex, smoking, and socioeconomic status. Mean NO2 was 5.4±1.6 ppb in London, Ontario. NO2 was associated with a significant increase in plaque (3.4 mm2 total carotid plaque area per 1 ppb NO2), exhibiting a linear dose-response. NO2 was also positively associated with triglycerides, total cholesterol, and the ratio of low- to high-density lipoprotein cholesterol (P<0.05). Diabetes mellitus mediated the relationship between NO2 and total carotid plaque area (P<0.05). Conclusions Our results demonstrate that even low levels of traffic-related air pollutants are linked to atherosclerotic plaque burden, an association that may be partially attributable to pollution-induced diabetes mellitus. Our findings suggest that reducing ambient concentrations in cities with NO2 below current standards would result in additional health benefits. Given the billions of people exposed to traffic emissions, our study supports the global public health significance of reducing air pollution.

Gallstone Ileus: Uncommon Presentation Followed by Less Common Spontaneous Resolution.

Gallstone ileus is a rare but significant cause of bowel obstruction. An 82-year-old female was admitted to the hospital with abdominal pain and was initially treated for a possible urinary tract infection. Following a surgical review and based on history, clinical examination as well as radiological findings, a diagnosis of gallstone ileus was made. The patient was prepared for surgery; however, whilst awaiting theatre, she spontaneously passed the obstructing gallstone with full resolution of bowel obstruction symptoms. The usual treatment for gallstone ileus is surgical management with an enterolithotomy; nevertheless, this case highlights the importance of close monitoring and adapting a management plan to fit an evolving clinical scenario.

Surveillance of cancer risks for firefighters, police, and armed forces among men in a Canadian census cohort.

BACKGROUND: Firefighters, police, and armed services may be exposed to hazards such as combustion by-products and shift work. METHODS: The CanCHEC cohort linked 1991 census data to the Canadian cancer registry for follow up. Cox proportional hazards modeling was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) to estimate risks for firefighter, police, or armed forces compared to workers in other occupations. RESULTS: The cohort of 1 108 410 men included 4535 firefighters, 10 055 police, and 9165 armed forces. For firefighters, elevated risks were noted for Hodgkin's lymphoma (HR: 2.89, 95%CI: 1.29-6.46), melanoma (HR: 1.67, 95%CI: 1.17-2.37), and prostate cancer (HR: 1.18, 95%CI: 1.01-1.37). Police had elevated risks for melanoma (HR:1.69, 95%CI: 1.32-2.16) and prostate cancer (HR:1.28, 95%CI: 1.14-1.42). No significant associations were found for armed forces workers. CONCLUSIONS: Canadian firefighters, police, and armed services, may be at an increased risk of developing certain cancers. Results suggested that a healthy worker effect may influence risk estimates.

Prostate cancer surveillance by occupation and industry: the Canadian Census Health and Environment Cohort (CanCHEC).

As there are no well-established modifiable risk factors for prostate cancer, further evidence is needed on possible factors such as occupation. Our study uses one of the largest Canadian worker cohorts to examine occupation, industry, and prostate cancer and to assess patterns of prostate cancer rates. The Canadian Census Health and Environment Cohort (CanCHEC) was established by linking the 1991 Canadian Census Cohort to the Canadian Cancer Database (1969-2010), Canadian Mortality Database (1991-2011), and Tax Summary Files (1981-2011). A total of 37,695 prostate cancer cases were identified in men aged 25-74 based on age at diagnosis. Cox proportional hazards models were used to estimate hazards ratios and 95% confidence intervals. In men aged 25-74 years, elevated risks were observed in the following occupations: senior management (HR = 1.12, 95% CI: 1.04-1.20); office and administration (HR = 1.19, 95% CI: 1.11-1.27); finance services (HR = 1.09, 95% CI: 1.04-1.14); education (HR = 1.05, 95% CI: 1.00-1.11); agriculture and farm management (HR = 1.12, 95% CI: 1.06-1.17); farm work (HR = 1.11, 95% CI: 1.01-1.21); construction managers (HR = 1.07, 95% CI: 1.01-1.14); firefighting (HR = 1.17, 95% CI: 1.01-1.36); and police work (HR = 1.22, 95% CI: 1.09-1.36). Decreased risks were observed across other construction and transportation occupations. Results by industry were consistent with occupation results. Associations were identified for white-collar, agriculture, protective services, construction, and transportation occupations. These findings emphasize the need for further study of job-related exposures and the potential influence of nonoccupational factors such as screening practices.

Alcohol distribution reforms and school proximity to liquor sales outlets in New Brunswick.

OBJECTIVES: The purpose of this project was to evaluate how changes to the sale of alcohol in New Brunswick would be distributed across urban and rural communities, and low- and high-income neighbourhoods. The study objectives were to 1) estimate the population living close to alcohol outlets before and after liquor distribution reforms, 2) identify communities or regions that would be more or less affected, and 3) determine whether expanding access to alcohol products would reduce school proximity to retailers. METHODS: Data from Statistics Canada, Desktop Mapping Technologies Inc. (DMTI), and geocoded publicly available information were spatially linked and analyzed using descriptive statistics. The populations living within 499 m, 500-999 m and 1-5 km of an outlet were estimated, and the distances from schools to stores were examined by geographic characteristics and neighbourhood socio-economic status. RESULTS: Permitting the sale of alcohol in all grocery stores throughout the province would increase the number of liquor outlets from 153 to 282 and would increase the population residing within 499 m of an outlet by 97.49%, from 19 886 to 39 273 residents. The sale of alcohol in grocery stores would result in an additional 35 liquor sales outlets being located within 499 m of schools. Low-income neighbourhoods would have the highest number and proportion of stores within 499 m of schools. CONCLUSION: The findings of this study demonstrate the importance of considering social, economic and health inequities in the context of alcohol policy reforms that will disproportionately affect low-income neighbourhoods and youth living within these areas.

Cancer Risks among Welders and Occasional Welders in a National Population-Based Cohort Study: Canadian Census Health and Environmental Cohort.

BACKGROUND: Welders are exposed to many known and suspected carcinogens. An excess lung cancer risk among welders is well established, but whether this is attributable to welding fumes is unclear. Excess risks of other cancers have been suggested, but not established. We investigated welding cancer risks in the population-based Canadian Census Health and Environmental Cohort. METHODS: Among 1.1 million male workers, 12,845 welders were identified using Standard Occupational Classification codes and followed through retrospective linkage of 1991 Canadian Long Form Census and Canadian Cancer Registry (1992-2010) records. Hazard ratios (HRs) were calculated using Cox proportional hazards models based on estimated risks of lung cancer, mesothelioma, and nasal, brain, stomach, kidney, and bladder cancers, and ocular melanoma. Lung cancer histological subtypes and risks by industry group and for occasional welders were examined. Some analyses restricted comparisons to blue-collar workers to minimize effects of potential confounders. RESULTS: Among welders, elevated risks were observed for lung cancer [HR: 1.16, 95% confidence interval (CI): 1.03-1.31], mesothelioma (HR: 1.78, 95% CI: 1.01-3.18), bladder cancer (HR: 1.40, 95% CI: 1.15-1.70), and kidney cancer (HR: 1.30, 95% CI: 1.01-1.67). When restricted to blue-collar workers, lung cancer and mesothelioma risks were attenuated, while bladder and kidney cancer risks increased. CONCLUSION: Excess risks of lung cancer and mesothelioma may be partly attributable to factors including smoking and asbestos. Welding-specific exposures may increase bladder and kidney cancer risks, and particular sources of exposure should be investigated. Studies that are able to disentangle welding effects from smoking and asbestos exposure are needed.

Occupational variation in incidence of bladder cancer: a comparison of population-representative cohorts from Nordic countries and Canada.

OBJECTIVES: The objective of this study was to compare occupational variation of the risk of bladder cancer in the Nordic countries and Canada. METHODS: In the Nordic Occupational Cancer study (NOCCA), 73 653 bladder cancer cases were observed during follow-up of 141.6 million person-years. In the Canadian Census Health and Environment Cohort (CanCHEC), 8170 cases were observed during the follow-up of 36.7 million person-years. Standardised incidence ratios with 95% CI were estimated for 53 occupations in the NOCCA cohort and HR with 95% CIs were estimated for 42 occupations in the CanCHEC. RESULTS: Elevated risks of bladder cancer were observed among hairdressers, printers, sales workers, plumbers, painters, miners and laundry workers. Teachers and agricultural workers had reduced risk of bladder cancer in both cohorts. Chimney-sweeps, tobacco workers and waiters had about 1.5-fold risk in the Nordic countries; no risk estimates for these categories were given from the CanCHEC cohort. CONCLUSION: We observed different occupational patterns in risk of bladder cancer in Nordic countries and Canada. The only occupation with similarly increased risk was observed among sales workers. Differences in smoking across occupational groups may explain some, but not all, of this variation.

Sedentary work and the risks of colon and rectal cancer by anatomical sub-site in the Canadian census health and environment cohort (CanCHEC).

BACKGROUND: Sedentary behaviour is a potential risk factor for colorectal cancer. We examined the association between sedentary work, based on body position, and colorectal cancer risk in Canadians. METHODS: A working body position category (a. sitting; b. standing and walking; c. sitting, standing, and walking; d. other) was assigned to occupations reported by 1991 Canadian Census respondents based on national occupational counselling guidelines. Adjusted hazard ratios (HRs) and 95% confidence intervals (CI) were estimated for cancers of the colon (overall, proximal, and distal) and rectum in men and women newly diagnosed from 1992 to 2010. RESULTS: Compared to "sitting" jobs, men in occupations with "other" (non-sitting, -standing, or -walking) body positions had a weakly significant reduced colon cancer risk (HR=0.93, 95% CI: 0.89, 0.98) primarily attributed to protection at the distal site (HR=0.90, 95% CI: 0.84, 0.97). Men in "standing and walking" and "sitting, standing, and walking" jobs did not have significantly reduced colon cancer risks. No effects were observed for rectal cancer in men or colon and rectal cancer in women. CONCLUSION: The two significant findings of this analysis should be followed-up in further investigations with additional information on potential confounders. Null findings for rectal cancer were consistent with other studies.

Cancer risks in a population-based study of 70,570 agricultural workers: results from the Canadian census health and Environment cohort (CanCHEC).

BACKGROUND: Agricultural workers may be exposed to potential carcinogens including pesticides, sensitizing agents and solar radiation. Previous studies indicate increased risks of hematopoietic cancers and decreased risks at other sites, possibly due to differences in lifestyle or risk behaviours. We present findings from CanCHEC (Canadian Census Health and Environment Cohort), the largest national population-based cohort of agricultural workers. METHODS: Statistics Canada created the cohort using deterministic and probabilistic linkage of the 1991 Canadian Long Form Census to National Cancer Registry records for 1992-2010. Self-reported occupations were coded using the Standard Occupational Classification (1991) system. Analyses were restricted to employed persons aged 25-74 years at baseline (N = 2,051,315), with follow-up until December 31, 2010. Hazard ratios (HR) and 95% confidence intervals (CI) were modeled using Cox proportional hazards for all workers in agricultural occupations (n = 70,570; 70.8% male), stratified by sex, and adjusted for age at cohort entry, province of residence, and highest level of education. RESULTS: A total of 9515 incident cancer cases (7295 in males) occurred in agricultural workers. Among men, increased risks were observed for non-Hodgkin lymphoma (HR = 1.10, 95% CI = 1.00-1.21), prostate (HR = 1.11, 95% CI = 1.06-1.16), melanoma (HR = 1.15, 95% CI = 1.02-1.31), and lip cancer (HR = 2.14, 95% CI = 1.70-2.70). Decreased risks in males were observed for lung, larynx, and liver cancers. Among female agricultural workers there was an increased risk of pancreatic cancer (HR = 1.36, 95% CI = 1.07-1.72). Increased risks of melanoma (HR = 1.79, 95% CI = 1.17-2.73), leukemia (HR = 2.01, 95% CI = 1.24-3.25) and multiple myeloma (HR = 2.25, 95% CI = 1.16-4.37) were observed in a subset of female crop farmers. CONCLUSIONS: Exposure to pesticides may have contributed to increased risks of hematopoietic cancers, while increased risks of lip cancer and melanoma may be attributed to sun exposure. The array of decreased risks suggests reduced smoking and alcohol consumption in this occupational group compared to the general population.

The emotional health and well-being of Canadians who care for persons with mental health or addictions problems.

The purpose of this project was to examine the emotional health and well-being of Canadian caregivers of persons with significant mental health or addictions problems. We assessed the emotional health of caregivers by care-receiver condition type (i.e. mental health or addictions vs. physical or other health problems), levels of caregiver stress and methods particularly for reducing stress among caregivers of persons with mental health or addictions disorders. Weighted cross-sectional data from the 2012 General Social Survey (Caregiving and Care Receiving) were modelled using weighted descriptive and logistic regression analyses to examine levels of stress and the emotional health and well-being of caregivers by care-receiver condition type. Caregivers of persons with mental health or addictions problems were more likely to report that caregiving was very stressful and that they felt depressed, tired, worried or anxious, overwhelmed; lonely or isolated; short-tempered or irritable; and resentful because of their caregiving responsibilities. The results of this study suggest that mental health and addictions caregivers may experience disparate stressors and require varying services and supports relative to caregivers of persons with physical or other health conditions.

Urban greenness and mortality in Canada's largest cities: a national cohort study.

BACKGROUND: Findings from published studies suggest that exposure to and interactions with green spaces are associated with improved psychological wellbeing and have cognitive, physiological, and social benefits, but few studies have examined their potential effect on the risk of mortality. We therefore undertook a national study in Canada to examine associations between urban greenness and cause-specific mortality. METHODS: We used data from a large cohort study (the 2001 Canadian Census Health and Environment Cohort [2001 CanCHEC]), which consisted of approximately 1·3 million adult (aged ≥19 years), non-immigrant, urban Canadians in 30 cities who responded to the mandatory 2001 Statistics Canada long-form census. The cohort has been linked by Statistics Canada to the Canadian mortality database and to annual income tax filings through 2011. We measured greenness with images from the moderate-resolution imaging spectroradiometer from NASA's Aqua satellite. We assigned estimates of exposure to greenness derived from remotely sensed Normalized Difference Vegetation Index (NDVI) within both 250 m and 500 m of participants' residences for each year during 11 years of follow-up (between 2001 and 2011). We used Cox proportional hazards models to estimate associations between residential greenness (as a continuous variable) and mortality. We estimated hazard ratios (HRs) and corresponding 95% CIs per IQR (0·15) increase in NDVI adjusted for personal (eg, education and income) and contextual covariates, including exposures to fine particulate matter, ozone, and nitrogen dioxide. We also considered effect modification by selected personal covariates (age, sex, household income adequacy quintiles, highest level of education, and marital status). FINDINGS: Our cohort consisted of approximately 1 265 000 individuals at baseline who contributed 11 523 770 person-years. We showed significant decreased risks of mortality in the range of 8-12% from all causes of death examined with increased greenness around participants' residence. In the fully adjusted analyses, the risk was significantly decreased for all causes of death (non-accidental HR 0·915, 95% CI 0·905-0·924; cardiovascular plus diabetes 0·911, 0·895-0·928; cardiovascular 0·911, 0·894-0·928; ischaemic heart disease 0·904, 0·882-0·927; cerebrovascular 0·942, 0·902-0·983; and respiratory 0·899, 0·869-0·930). Greenness associations were more protective among men than women (HR 0·880, 95% CI 0·868-0·893 vs 0·955, 0·941-0·969), and among individuals with higher incomes (highest quintile 0·812, 0·791-0·834 vs lowest quintile 0·991, 0·972-1·011) and more education (degree or more 0·816, 0·791-0·842 vs did not complete high school 0·964, 0·950-0·978). INTERPRETATION: Increased amounts of residential greenness were associated with reduced risks of dying from several common causes of death among urban Canadians. We identified evidence of inequalities, both in terms of exposures to greenness and mortality risks, by personal socioeconomic status among individuals living in generally similar environments, and with reasonably similar access to health care and other social services. The findings support the development of policies related to creating greener and healthier cities. FUNDING: None.

The influence of community well-being on mortality among Registered First Nations people.

BACKGROUND: Living in a community with lower socioeconomic status is associated with higher mortality. However, few studies have examined associations between community socioeconomic characteristics and mortality among the First Nations population. DATA AND METHODS: The 1991-to-2006 Census Mortality and Cancer Cohort follow-up, which tracked a 15% sample of Canadians aged 25 or older, included 57,300 respondents who self-identified as Registered First Nations people or Indian band members. The Community Well-Being Index (CWB), a measure of the social and economic well-being of communities, consists of income, education, labour force participation, and housing components. A dichotomous variable was used to indicate residence in a community with a CWB score above or below the average for First Nations communities. Age-standardized mortality rates (ASMRs) were calculated for First Nations cohort members in communities with CWB scores above and below the First Nations average. Cox proportional hazards models examined the impact of CWB when controlling for individual characteristics. RESULTS: The ASMR for First Nations cohort members in communities with a below-average CWB was 1,057 per 100,000 person-years at risk, compared with 912 for those in communities with an above-average CWB score. For men, living in a community with below-average income and labour force participation CWB scores was associated with an increased hazard of death, even when individual socioeconomic characteristics were taken into account. Women in communities with below-average income scores had an increased hazard of death. INTERPRETATION: First Nations people in communities with below-average CWB scores tended to have higher mortality rates. For some components of the CWB, effects remained even when individual socioeconomic characteristics were taken into account.

A national study of the association between traffic-related air pollution and adverse pregnancy outcomes in Canada, 1999-2008.

Numerous studies have examined the association of air pollution with preterm birth and birth weight outcomes. Traffic-related air pollution has also increasingly been identified as an important contributor to adverse health effects of air pollution. We employed a national nitrogen dioxide (NO2) exposure model to examine the association between NO2 and pregnancy outcomes in Canada between 1999 and 2008. National models for NO2 (and particulate matter of median aerodynamic diameter <2.5µm (PM2.5) as a covariate) were developed using ground-based monitoring data, estimates from remote-sensing, land use variables and, for NO2, deterministic gradients relative to road traffic sources. Generalized estimating equations were used to examine associations with preterm birth, term low birth weight (LBW), small for gestational age (SGA) and term birth weight, adjusting for covariates including infant sex, gestational age, maternal age and marital status, parity, urban/rural place of residence, maternal place of birth, season, year of birth and neighbourhood socioeconomic status and per cent visible minority. Associations were reduced considerably after adjustment for individual covariates and neighbourhood per cent visible minority, but remained significant for SGA (odds ratio 1.04, 95%CI 1.02-1.06 per 20ppb NO2) and term birth weight (16.2g reduction, 95% CI 13.6-18.8g per 20ppb NO2). Associations with NO2 were of greater magnitude in a sensitivity analysis using monthly monitoring data, and among births to mothers born in Canada, and in neighbourhoods with higher incomes and a lower proportion of visible minorities. In two pollutant models, associations with NO2 were less sensitive to adjustment for PM2.5 than vice versa, and there was consistent evidence of a dose-response relationship for NO2 but not PM2.5. In this study of approximately 2.5 million Canadian births between 1999 and 2008, we found significant associations of NO2 with SGA and term birth weight which remained significant after adjustment for PM2.5, suggesting that traffic may be a particularly important source with respect to the role of air pollution as a risk factor for adverse pregnancy outcomes.

A New Method to Jointly Estimate the Mortality Risk of Long-Term Exposure to Fine Particulate Matter and its Components.

Most studies on the association between exposure to fine particulate matter (PM2.5) and mortality have considered only total concentration of PM2.5 or individual components of PM2.5, and not the combined effects of concentration and particulate composition. We sought to develop a method to estimate the risk of death from long-term exposure to PM2.5 and the distribution of its components, namely: sulphate, nitrate, ammonium, organic mass, black carbon, and mineral dust. We decomposed PM2.5 exposure into the sum of total concentration and the proportion of each component. We estimated the risk of death due to exposure using a cohort of ~2.4 million Canadians who were followed for vital status over 16 years. Modelling the concentration of PM2.5 with the distribution of the proportions of components together was a superior predictor for mortality than either total PM2.5 concentration alone, or all component concentrations modelled together. Our new approach has the advantage of characterizing the toxicity of the atmosphere in its entirety. This is required to fully understand the health benefits associated with strategies to improve air quality that may result in complex changes not only in PM2.5 concentration, but also in the distribution of particle components.

Associations of Pregnancy Outcomes and PM2.5 in a National Canadian Study.

BACKGROUND: Numerous studies have examined associations between air pollution and pregnancy outcomes, but most have been restricted to urban populations living near monitors. OBJECTIVES: We examined the association between pregnancy outcomes and fine particulate matter in a large national study including urban and rural areas. METHODS: Analyses were based on approximately 3 million singleton live births in Canada between 1999 and 2008. Exposures to PM2.5 (particles of median aerodynamic diameter ≤ 2.5 µm) were assigned by mapping the mother's postal code to a monthly surface based on a national land use regression model that incorporated observations from fixed-site monitoring stations and satellite-derived estimates of PM2.5. Generalized estimating equations were used to examine the association between PM2.5 and preterm birth (gestational age < 37 weeks), term low birth weight (< 2,500 g), small for gestational age (SGA; < 10th percentile of birth weight for gestational age), and term birth weight, adjusting for individual covariates and neighborhood socioeconomic status (SES). RESULTS: In fully adjusted models, a 10-µg/m(3) increase in PM2.5 over the entire pregnancy was associated with SGA (odds ratio = 1.04; 95% CI 1.01, 1.07) and reduced term birth weight (-20.5 g; 95% CI -24.7, -16.4). Associations varied across subgroups based on maternal place of birth and period (1999-2003 vs. 2004-2008). CONCLUSIONS: This study, based on approximately 3 million births across Canada and employing PM2.5 estimates from a national spatiotemporal model, provides further evidence linking PM2.5 and pregnancy outcomes.

Ambient PM2.5, O3, and NO2 Exposures and Associations with Mortality over 16 Years of Follow-Up in the Canadian Census Health and Environment Cohort (CanCHEC).

BACKGROUND: Few studies examining the associations between long-term exposure to ambient air pollution and mortality have considered multiple pollutants when assessing changes in exposure due to residential mobility during follow-up. OBJECTIVE: We investigated associations between cause-specific mortality and ambient concentrations of fine particulate matter (≤ 2.5 µm; PM2.5), ozone (O3), and nitrogen dioxide (NO2) in a national cohort of about 2.5 million Canadians. METHODS: We assigned estimates of annual concentrations of these pollutants to the residential postal codes of subjects for each year during 16 years of follow-up. Historical tax data allowed us to track subjects' residential postal code annually. We estimated hazard ratios (HRs) for each pollutant separately and adjusted for the other pollutants. We also estimated the product of the three HRs as a measure of the cumulative association with mortality for several causes of death for an increment of the mean minus the 5th percentile of each pollutant: 5.0 µg/m3 for PM2.5, 9.5 ppb for O3, and 8.1 ppb for NO2. RESULTS: PM2.5, O3, and NO2 were associated with nonaccidental and cause-specific mortality in single-pollutant models. Exposure to PM2.5 alone was not sufficient to fully characterize the toxicity of the atmospheric mix or to fully explain the risk of mortality associated with exposure to ambient pollution. Assuming additive associations, the estimated HR for nonaccidental mortality corresponding to a change in exposure from the mean to the 5th percentile for all three pollutants together was 1.075 (95% CI: 1.067, 1.084). Accounting for residential mobility had only a limited impact on the association between mortality and PM2.5 and O3, but increased associations with NO2. CONCLUSIONS: In this large, national-level cohort, we found positive associations between several common causes of death and exposure to PM2.5, O3, and NO2. CITATION: Crouse DL, Peters PA, Hystad P, Brook JR, van Donkelaar A, Martin RV, Villeneuve PJ, Jerrett M, Goldberg MS, Pope CA III, Brauer M, Brook RD, Robichaud A, Menard R, Burnett RT. 2015. Ambient PM2.5, O3, and NO2 exposures and associations with mortality over 16 years of follow-up in the Canadian Census Health and Environment Cohort (CanCHEC). Environ Health Perspect 123:1180-1186; http://dx.doi.org/10.1289/ehp.1409276.

Maternal and community predictors of gastroschisis and congenital diaphragmatic hernia in Canada.

PURPOSE: The incidence of gastroschisis (GS) has increased globally. Maternal age and smoking are risk factors and aboriginal communities may be more commonly affected. Factors leading to this increased incidence are otherwise unclear. We investigate maternal sociodemography, air pollution and personal risk factors comparing mothers of infants with GS with a control group of infants with diaphragmatic hernia (CDH) in a large population-based analysis. METHODS: Data were collected from a national, disease-specific pediatric surgical database (May 2006-June 2013). Maternal community sociodemographic information was derived from the Canadian 2006 Census. Univariate and multivariable analyses were performed examining maternal factors related to diagnosis of GS. RESULTS: GS infants come from poorer, less educated communities with more unemployment, less pollution, fewer immigrants, and more aboriginal peoples than infants with CDH. Teen maternal age, smoking, and illicit drug use, are associated with GS. CONCLUSION: Mothers of infants with GS are younger, more likely to smoke and come from socially disadvantaged communities with higher proportions of aboriginal peoples but lower levels of air pollution compared to mothers of CDH infants. Identification of maternal risks provides direction for prenatal screening and public health interventions.