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Outdoor fine particulate air pollution (PM 2.5 ) is known to increase mortality risk and is recognized as an important contributor to global disease burden. However, less is known about how oxidant gases may modify the chronic health effects of PM 2.5 . In this study, we examined how the oxidant capacity of O 3 and NO 2 (using a redox-weighted average, O x ) may modify the relationship between PM 2.5 and mortality in the 2001 Canadian Census Health and Environment Cohort. In total, 2,448,500 people were followed over a 10.6-year period. Each 3.86 µg/m 3 increase in PM 2.5 was associated with nonaccidental (Hazard Ratio (HR) = 1.095, 95% CI: 1.077, 1.112), cardiovascular (HR = 1.088, 95% CI: 1.059, 1.118), and respiratory mortality (HR = 1.110, 95% CI: 1.051, 1.171) in the highest tertile of O x whereas weaker/null associations were observed in the middle and lower tertiles. Analysis of joint non-linear concentration-response relationships for PM 2.5 and O x suggested threshold concentrations between approximately 23 and 25 ppb with O x concentrations above these values strengthening PM 2.5 -mortality associations. Overall, our findings suggest that oxidant gases enhance the chronic health risks of PM 2.5 . In some areas, reductions in O x concentrations may have the added benefit of reducing the public health impacts of PM 2.5 even if mass concentrations remain unchanged.

Background Approximately 2.9 million deaths are attributed to ambient fine particle air pollution around the world each year (PM 2.5 ). In general, cohort studies of mortality and outdoor PM 2.5 concentrations have limited information on individuals exposed to low levels of PM 2.5 as well as covariates such as smoking behaviours, alcohol consumption, and diet which may confound relationships with mortality. This study provides an updated and extended analysis of the Canadian Community Health Survey-Mortality cohort: a population-based cohort with detailed PM 2.5 exposure data and information on a number of important individual-level behavioural risk factors. We also used this rich dataset to provide insight into the shape of the concentration-response curve for mortality at low levels of PM 2.5 . Methods Respondents to the Canadian Community Health Survey from 2000 to 2012 were linked by postal code history from 1981 to 2016 to high resolution PM 2.5 exposure estimates, and mortality incidence to 2016. Cox proportional hazard models were used to estimate the relationship between non-accidental mortality and ambient PM 2.5 concentrations (measured as a three-year average with a one-year lag) adjusted for socio-economic, behavioural, and time-varying contextual covariates. Results In total, 50,700 deaths from non-accidental causes occurred in the cohort over the follow-up period. Annual average ambient PM 2.5 concentrations were low (i.e. 5.9 μg/m 3 , s.d. 2.0) and each 10 μg/m 3 increase in exposure was associated with an increase in non-accidental mortality (HR = 1.11; 95% CI 1.04–1.18). Adjustment for behavioural covariates did not materially change this relationship. We estimated a supra-linear concentration-response curve extending to concentrations below 2 μg/m 3 using a shape constrained health impact function. Mortality risks associated with exposure to PM 2.5 were increased for males, those under age 65, and non-immigrants. Hazard ratios for PM 2.5 and mortality were attenuated when gaseous pollutants were included in models. Conclusions Outdoor PM 2.5 concentrations were associated with non-accidental mortality and adjusting for individual-level behavioural covariates did not materially change this relationship. The concentration-response curve was supra-linear with increased mortality risks extending to low outdoor PM 2.5 concentrations.

Ambient fine particulate air pollution with aerodynamic diameter ( ) is an important contributor to the global burden of disease. Information on the shape of the concentration-response relationship at low concentrations is critical for estimating this burden, setting air quality standards, and in benefits assessments. We examined the concentration-response relationship between and nonaccidental mortality in three Canadian Census Health and Environment Cohorts (CanCHECs) based on the 1991, 1996, and 2001 census cycles linked to mobility and mortality data. Census respondents were linked with death records through 2016, resulting in 8.5 million adults, 150 million years of follow-up, and 1.5 million deaths. Using annual mailing address, we assigned time-varying contextual variables and 3-y moving-average ambient at a spatial resolution from 1988 to 2015. We ran Cox proportional hazards models for adjusted for eight subject-level indicators of socioeconomic status, seven contextual covariates, ozone, nitrogen dioxide, and combined oxidative potential. We used three statistical methods to examine the shape of the concentration-response relationship between and nonaccidental mortality. The mean 3-y annual average estimate of exposure ranged from 6.7 to over the three cohorts. We estimated a hazard ratio (HR) of 1.053 [95% confidence interval (CI): 1.041, 1.065] per change in after pooling the three cohort-specific hazard ratios, with some variation between cohorts (1.041 for the 1991 and 1996 cohorts and 1.084 for the 2001 cohort). We observed a supralinear association in all three cohorts. The lower bound of the 95% CIs exceeded unity for all concentrations in the 1991 cohort, for concentrations above in the 1996 cohort, and above in the 2001 cohort. In a very large population-based cohort with up to 25 y of follow-up, was associated with nonaccidental mortality at concentrations as low as . https://doi.org/10.1289/EHP5204.

Background Understanding the shape of the relationship between long-term exposure to ambient fine particulate matter (PM 2.5 ) concentrations and health risks is critical for health impact and risk assessment. Studies evaluating the health risks of exposure to low concentrations of PM 2.5 are limited. Further, many existing studies lack individual-level information on potentially important behavioural confounding factors. Methods A prospective cohort study was conducted among a subset of participants in a cohort that linked respondents of the Canadian Community Health Survey to mortality ( n  = 299,500) with satellite-derived ambient PM2.5 estimates. Participants enrolled between 2000 and 2008 were followed to date of death or December 31, 2011. Cox proportional hazards models were used to estimate hazard ratios (HRs) for mortality attributed to PM 2.5 exposure, adjusted for individual-level and contextual covariates, including smoking behaviour and body mass index (BMI). Results Approximately 26,300 non-accidental deaths, of which 32.5 % were due to circulatory disease and 9.1 % were due to respiratory disease, occurred during the follow-up period. Ambient PM 2.5 exposures were relatively low (mean = 6.3 μg/m 3 ), yet each 10 μg/m 3 increase in exposure was associated with increased risks of non-accidental (HR = 1.26; 95 % CI: 1.19-1.34), circulatory disease (HR = 1.19; 95 % CI: 1.07–1.31), and respiratory disease mortality (HR = 1.52; 95 % CI: 1.26–1.84) in fully adjusted models. Higher hazard ratios were observed for respiratory mortality among respondents who never smoked (HR = 1.97; 95 % CI: 1.24–3.13 vs. HR = 1.45; 95 % CI: 1.17–1.79 for ever smokers), and among obese (BMI ≥ 30) respondents (HR = 1.76; 95 % CI: 1.15-2.69 vs. HR = 1.41; 95 % CI: 1.04–1.91 for normal weight respondents), though differences between groups were not statistically significant. A threshold analysis for non-accidental mortality estimated a threshold concentration of 0 μg/m 3 (+95 % CI = 4.5 μg/m 3 ). Conclusions Increased risks of non-accidental, circulatory, and respiratory mortality were observed even at very low concentrations of ambient PM 2.5 . HRs were generally greater than most literature values, and adjusting for behavioural covariates served to reduce HR estimates slightly.

Increasing evidence suggests that residential exposures to natural environments, such as green spaces, are associated with many health benefits. Only a single study has examined the potential link between living near water and mortality. We sought to examine whether residential proximity to large, natural water features (e.g., lakes, rivers, coasts, \"blue space\") was associated with cause-specific mortality. Our study is based on a population-based cohort of nonimmigrant adults living in the 30 largest Canadian cities [i.e., the 2001 Canadian Census Health and Environment Cohort) (CanCHEC)]. Subjects were drawn from the mandatory 2001 Statistics Canada long-form census, who were linked to the Canadian mortality database and to annual income-tax filings, through 2011. We estimated associations between living within of blue space and deaths from several common causes of death. We adjusted models for many personal and contextual covariates, as well as for exposures to residential greenness and ambient air pollution. Our cohort included approximately 1.3 million subjects at baseline, 106,180 of whom died from nonaccidental causes during follow-up. We found significant, reduced risks of mortality in the range of 12-17% associated with living within of water in comparison with living farther away, among all causes of death examined, except with external/accidental causes. Protective effects were found to be higher among women and all older adults than among other subjects, and protective effects were found to be highest against deaths from stroke and respiratory-related causes. Our findings suggest that living near blue spaces in urban areas has important benefits to health, but further work is needed to better understand the drivers of this association. https://doi.org/10.1289/EHP3397.

Background Several recent climate change reviews have stressed the possibility of some malaria vectors occupying regions of higher altitudes than previously recorded. Indeed, highland malaria has been observed in several African nations, possibly attributable to changes in land use, vector control and local climate. This study attempts to expand the current knowledge of the distribution of common Anopheles species in Ecuador, with particular attention to highland regions (> 500 m) of the Andes. Methods Extensive field collections of larvae were undertaken in 2008, 2009 and 2010 throughout all regions of Ecuador (except the lower-altitude Amazonian plain) and compared to historical distribution maps reproduced from the 1940s. Larvae were identified using both a morphological key and sequencing of the 800 bp region of the CO1 mitochondrial gene. In addition, spatial statistics (Getis-Ord Hotspot Analysis: Gi*) were used to determine high and low-density clusters of each species in Ecuador. Results Distributions have been updated for five species of Anopheles in Ecuador: Anopheles albimanus , Anopheles pseudopunctipennis , Anopheles punctimacula , Anopheles eiseni and Anopheles oswaldoi s.l .. Historical maps indicate that An. pseudopunctipennis used to be widespread in highland Andean valleys, while other species were completely restricted to lowland areas. By comparison, updated maps for the other four collected species show higher maximum elevations and/or more widespread distributions in highland regions than previously recorded. Gi* analysis determined some highland hot spots for An. albimanus , but only cold spots for all other species. Conclusions This study documents the establishment of multiple anopheline species in high altitude regions of Ecuador, often in areas where malaria eradication programs are not focused.

Background Numerous studies have examined the association between air pollution and preterm birth (< 37 weeks gestation) but findings have been inconsistent. These associations may be more difficult to detect than associations with other adverse birth outcomes because of the different duration of exposure in preterm vs. term births, and the existence of seasonal cycles in incidence of preterm birth. Methods We analyzed data pertaining to 1,001,700 singleton births occurring between 1999 and 2008 in 24 Canadian cities where daily air pollution data were available from government monitoring sites. In the first stage, data were analyzed in each city employing Cox proportional hazards models using gestational age in days as the time scale, obtaining city-specific hazard ratios (HRs) with their 95% confidence intervals (CIs) expressed per interquartile range (IQR) of each air pollutant. Effects were examined using distributed lag functions for lags of 0–6 days prior to delivery, as well as cumulative lags from two to six days. We accounted for the potential nonlinear effect of daily mean ambient temperature using a cubic B-spline with three internal knots. In the second stage, we pooled the estimated city-specific hazard ratios using a random effects model. Results Pooled estimates across 24 cities indicated that an IQR increase in ozone (O 3 , 13.3 ppb) 0–3 days prior to delivery was associated with a hazard ratio of 1.036 (95% CI 1.005, 1.067) for preterm birth, adjusting for infant sex, maternal age, marital status and country of birth, neighbourhood socioeconomic status (SES) and visible minority, temperature, year and season of birth, and a natural spline function of day of year. There was some evidence of effect modification by gestational age and season. Associations with carbon monoxide, nitrogen dioxide, particulate matter, and sulphur dioxide were inconsistent. Conclusions We observed associations between daily O 3 in the week before delivery and preterm birth in an analysis of approximately 1 million births in 24 Canadian cities between 1999 and 2008. Our analysis is one of a limited number which have examined these short term associations employing Cox proportional hazards models to account for the different exposure durations of preterm vs. term births.

Recent collection data indicate that at least four potential malaria vectors occupy more widespread distributions within the Andean highlands than in the past. Since habitat elimination is an important aspect of malaria control, it is vital to characterize larval habitats for Anopheles species within both lowland and highland sites. To that end, 276 sites within Ecuador were surveyed between 2008 and 2010. Characteristics of Anopheles-present sites for four species were compared to Anopheles-absent sites within the same geographical range and also to Anopheles-absent sites within a highland range representing potential future habitats. Thermochron iButtons© were used to describe the daily temperature variation within a subset of potential habitats. Anopheles albimanus (W.) was positively associated with permanent habitats, sand substrates, floating algae (cyanobacterial mats), and warmer temperatures in both comparisons. Anopheles pseudopunctipennis (T.) was associated with floating algae (cyanobacterial mats), warmer temperatures, and higher water clarity in both comparisons. Anopheles punctimacula (D.&K.) was negatively associated with floating algae and positively associated with dissolved oxygen in both comparisons. Anopheles oswaldoi s. l. (P.) was not significantly associated with any parameters more often than expected given larval-absent sites. The results indicate that minimum water temperatures might limit the upper altitudinal distribution of An. albimanus (18.7° C) and An. pseudopunctipennis (16.0° C).

Ultraviolet radiation (UVR) exposure and a history of sunburn are important risk factors for skin cancer. Sunburn is more common among men, younger age groups, and people in higher income households. Sun protection measures also vary by sex, age, and socioeconomic characteristics. Associations between ambient UVR and sunburn and sun safety measures have not been quantified. A total of 53,130 respondents aged 18 or older answered a Canadian Community Health Survey (CCHS) module on sun safety, which was administered in six provinces from 2005 to 2014. The module contained questions about sunburn, time in the sun, and sun protection. These respondents were linked to an ambient erythemal UVR dataset representing the June-to-August mean. Descriptive statistics and logistic regression were used to examine associations between population characteristics, sunburn, sun safety, time in the sun, and ambient UVR. Sunburn was reported by 33% of respondents and was more common among men, younger age groups, people who were not members of visible minorities, residents of higher income households, and individuals who were employed. On a typical summer day, a larger percentage of women than men sought shade and wore sunscreen, whereas a larger percentage of men wore a hat or long pants. As ambient summer UVR increased, women were more likely to apply sunscreen to their face, seek shade, or wear a hat (OR~1.02 to 1.09 per increase of 187 J/m² of erythemally-weighted UVR, or 5.4% of the mean); these associations were not observed among men. Findings related to sunburn and sun protection were similar to those of previous studies. The association between ambient UVR and women's precautionary measures suggests that information about UVR may influence their decision to protect their skin.

The Canadian Census Health and Environment Cohorts (CanCHECs) are population-based linked datasets of the household population at the time of census collection. The CanCHECs combine data from respondents to the long-form census or the National Household Survey between 1991 and 2011 with administrative health data (e.g., mortality, cancer incidence, hospitalizations, emergency ambulatory care) and annual mailing address postal codes. The CanCHEC datasets are rich national data resources that can be used to measure and examine health inequalities across socioeconomic and ethnocultural dimensions for different periods and locations. These datasets can also be used to examine the effects of exposure to environmental factors on human health. Because of their large size, the CanCHECs are an excellent resource for examining rare health outcomes and small population groups. They are ideally suited for environmental health research because of their geographic coverage across all regions of Canada, their long follow-up periods and their linkage to annual postal code history.