January 28 | 2019

The heat penalty of walkable neighbourhoods. 

O’Brien GA, Ross NA, Strachan IB.

Int J Biometeorol. 2019 Jan 24.. [Epub ahead of print] DOI: 10.1007/s00484-018-01663-0



« Walkability » or walking-friendliness is generally considered a favourable attribute of a neighbourhood that supports physical activity and improves health outcomes. Walkable neighbourhoods tend to have high-density infrastructure and relatively high amounts of concrete and pavement for sidewalks and streets, all of which can elevate local urban temperatures. The objective of this study was to assess whether there is a « heat penalty » associated with more walkable neighbourhoods in Montréal, Québec, Canada, using air temperature measurements taken in real time at street level during a heat event. The mean temperature of « Car-Dependent » neighbourhoods was 26.2 °C (95% CI 25.8, 26.6) whereas the mean temperature of « Walker’s Paradise » neighbourhoods was 27.9 °C (95% CI 27.8, 28.1)-a difference of 1.7 °C (95% CI 1.3, 2.0). There was a strong association between higher walkability of Montréal neighbourhoods and elevated temperature (r = 0.61, p < 0.01); suggestive of a heat penalty for walkable neighbourhoods. Planning solutions that support increased walking-friendliness of neighbourhoods should consider simultaneous strategies to mitigate heat to reduce potential health consequences of the heat penalty.

January 21 | 2019

Residential greenness and mortality in oldest-old women and men in China: a longitudinal cohort study.

John S Ji ScD, Anna Zhu MSc, Chen Bai PhD, Chih-Da Wu PhD, Lijing Yan PhD, Prof Shenglan Tang PhD, Prof Yi Zeng PhD, Peter James ScD.

The Lancet Planetary Health,Volume 3, Issue 1, January 2019, Pages e17-e25 https://doi.org/10.1016/S2542-5196(18)30264-X




Exposure to natural vegetation, or greenness, might affect health through several pathways, including increased physical activity and social engagement, improved mental health, and reductions in exposure to air pollution, extreme temperatures, and noise. Few studies of the effects of greenness have focused on Asia, and, to the best of our knowledge, no study has assessed the effect on vulnerable oldest-old populations. We assessed the association between residential greenness and mortality in an older cohort in China.


We used five waves (February, 2000–October, 2014) of the China Longitudinal Healthy Longevity Survey (CLHLS), a prospective cohort representative of the general older population in China. We assessed exposure to greenness through satellite-derived Normalised Difference Vegetation Index (NDVI) values in the 250 m and 1250 m radius around the residential address for each individual included in the study. We calculated contemporaneous NDVI values, cumulative NDVI values, and changes in NDVI from the start of the study over time. The health outcome of the study was all-cause mortality, excluding accidental deaths. Mortality rate ratios were estimated with Cox proportional hazards models, adjusted for age, sex, ethnicity, marital status, geographical region, childhood and adult socioeconomic status, social and leisure activity, smoking status, alcohol consumption, and physical activity.


Among 23 754 individuals (mean age at baseline 93 years [SD 7·5]) totaling 80 001 person-years, we observed 18 948 deaths during 14 years of follow-up, between June, 2000, and December, 2014. Individuals in the highest quartile of contemporaneous NDVI values had 27% lower mortality than those in the lowest quartile for the 250 m radius (hazard ratio [HR] 0·73, 95% CI 0·70–0·76), and 30% lower mortality for the 1250 m radius (0·70, 0·67–0·74). No clear association was observed for cumulative NDVI measurements and mortality. We did not detect an association between area-level changes in NDVI and mortality.


Our research suggests that proximity to more green space is associated with increased longevity, which has policy implications for the national blueprint of ecological civilisation and preparation for an ageing society in China.

January 14 | 2019

Residential noise exposure and the longitudinal risk of hospitalization for depression after pregnancy: Postpartum and beyond. 

He S, Smargiassi A, Low N, Bilodeau-Bertrand M, Ayoub A, Auger N.

Environ Res. 2018 Dec 3;170:26-32. doi: 10.1016/j.envres.2018.12.001  [Epub ahead of print]



Depression is a major public health concern, but the link with the built environment is unclear. We sought to determine the relationship between residential noise during pregnancy and later risk of severe depression in women.


We analyzed a population-based cohort of 140,456 women with no documented history of mental illness who were pregnant in Montreal between 2000 and 2016. We obtained residential noise estimates (LAeq. 24 h, Lden, Lnight) from land use regression models, and followed the women over time for up to 18 years after pregnancy to identify subsequent hospitalizations for depression or other mental disorders. We used Cox regression to compute hazard ratios and 95% confidence intervals (CI) adjusted for maternal characteristics.


There were 8.0 incident hospitalizations for depression and 16.4 for other mental disorders per 10,000 person-years in women exposed to an LAeq. 24 h of 60-64.9 dB(A). The incidence was lower for noise at < 55 dB(A), with 7.4 hospitalizations for depression and 13.8 for other mental disorders per 10,000 person-years. Compared with 50 dB(A), an LAeq. 24 h of 60 dB(A) was associated with 1.16 times (95% CI 0.84-1.62) the risk of depression hospitalization, and 1.34 times (95% CI 1.04-1.74) the risk of other mental disorders. Associations were more prominent for Lnight, with 1.32 times (95% CI 1.08-1.63) the risk of depression hospitalization at 60 dB(A) and 1.68 times the risk (95% CI 1.05-2.67) at 70 dB(A).


Pregnant women exposed to noise, especially nighttime noise, have a greater risk of hospitalization for depression and other mental disorders later in life. Residential noise may be a risk factor for depression after pregnancy.

Spotlight: Marianne Hatzopoulou

Marianne co-leads the Transportation group within CANUE. The main objective of the transportation group is to generate traffic volumes on road networks for various Canadian cities. The team is using various approaches including travel demand and network assignment models as well as statistical interpolation techniques.

Marianne Hatzopoulou is Associate Professor in the Department of Civil Engineering at the University of Toronto and Canada Research Chair in Transportation and Air Quality. Her expertise is in modelling road transport emissions and urban air quality, as well as evaluating population exposure to air pollution. Her research aims to capture the interactions between the daily activities and travel patterns of urban dwellers and the generation and dispersion of traffic emissions in urban environments. She has linked various traffic simulation models with tools for microscopic emission estimates and has published in the areas of traffic emission modeling, near-road air pollution, and greenhouse gas emissions from transport. Prof. Hatzopoulou serves on the National Academy of Science Transportation Research Board committees on “Transportation and Air Quality” and “Environmental Analysis in Transportation”.

University of Toronto profile

January 7 | 2019

Born to be Wise: a population registry data linkage protocol to assess the impact of modifiable early-life environmental exposures on the health and development of children. 

van den Bosch M, Brauer M, Burnett R, Davies HW, Davis Z, Guhn M, Jarvis I, Nesbitt L, Oberlander T, Rugel E, Sbihi H, Su JG, Jerrett M.

BMJ Open. 2018 Dec 14;8(12):e026954. doi: 10.1136/bmjopen-2018-026954



Deficiencies in childhood development is a major global issue and inequalities are large. The influence of environmental exposures on childhood development is currently insufficiently explored. This project will analyse the impact of various modifiable early life environmental exposures on different dimensions of childhood development.


Born to be Wise will study a Canadian cohort of approximately 34 000 children who have completed an early development test at the age of 5. Land use regression models of air pollution and spatially defined noise models will be linked to geocoded data on early development to analyse any harmful effects of these exposures. The potentially beneficial effect on early development of early life exposure to natural environments, as measured by fine-grained remote sensing data and various land use indexes, will also be explored. The project will use data linkages and analyse overall and age-specific impact, including variability depending on cumulative exposure by assigning time-weighted exposure estimates and by studying subsamples who have changed residence and exposure. Potentially moderating effects of natural environments on air pollution or noise exposures will be studied by mediation analyses. A matched case-control design will be applied to study moderating effects of natural environments on the association between low socioeconomic status and early development. The main statistical approach will be mixed effects models, applying a specific software to deal with multilevel random effects of nested data. Extensive confounding control will be achieved by including data on a range of detailed health and sociodemographic variables.


The study protocol has been ethically approved by the Behavioural Research Ethics Board at the University of British Columbia. The findings will be published in peer-reviewed journals and presented at scholarly conferences. Through stakeholder engagement, the results will also reach policy and a broader audience.