Who are more exposed to PM2.5 pollution: A mobile phone data approach.

BACKGROUND: Few studies have examined exposure disparity to ambient air pollution outside North America and Europe. Moreover, very few studies have investigated exposure disparity in terms of individual-level data or at multi-temporal scales. OBJECTIVES: This work aims to examine the associations between individual- and neighbourhood-level economic statuses and individual exposure to PM2.5 across multi-temporal scales. METHODS: The study population included 742,220 mobile phone users on a weekday in Shenzhen, China. A geo-informed backward propagation neural network model was developed to estimate hourly PM2.5 concentrations by the use of remote sensing and geospatial big data, which were then combined with individual trajectories to estimate individual total exposure during weekdays at multi-temporal scales. Coupling the estimated PM2.5 exposure with housing price, we examined the associations between individual- and neighbourhood-level economic statuses and individual exposure using linear regression and two-level hierarchical linear models. Furthermore, we performed five sensitivity analyses to test the robustness of the two-level effects. RESULTS: We found positive associations between individual- and neighbourhood-level economic statuses and individual PM2.5 exposure at a daytime, daily, weekly, monthly, seasonal or annual scale. Findings on the effects of the two-level economic statuses were generally robust in the five sensitivity analyses. In particular, despite the insignificant effects observed in three of newly selected time periods in the sensitivity analysis, individual- and neighbourhood-level economic statuses were still positively associated with individual total exposure during each of other newly selected periods (including three other seasons). CONCLUSIONS: There are statistically positive associations of individual PM2.5 exposure with individual- and neighbourhood-level economic statuses. That is, people living in areas with higher residential property prices are more exposed to PM2.5 pollution. Findings emphasize the need for public health intervention and urban planning initiatives targeting socio-economic disparity in ambient air pollution exposure, thus alleviating health disparities across socioeconomic groups.

Informal social support and older persons' psychological well-being in Hong Kong.

This paper focuses on the importance and the effectiveness of various types of informal support for older persons' psychological well-being. It examines the effects of objective measures of informal support (such as size of social networks and frequency of contact) and subjective measures (such as satisfaction with the support received) on psychological well-being of older occupants in different household circumstances (i.e.,living alone, with spouse or relatives, in old urban areas or new towns, in private or public housing). Data were collected from face-to-face interviews with a sample of 518 older persons (224 males, 294 females) aged 60 and over, systematically drawn from a GIS-derived framework of housing districts in old urban areas and new towns in Hong Kong. The results show that both objective and subjective measures of informal support were related to older persons' psychological well-being, but subjective measures of informal support (specifically satisfaction with support received from family members) were found to be more important predictors of psychological well-being. Furthermore, the effects of size of social network on psychological well-being were stronger for older persons who lived alone than for those who lived with a spouse or relatives. The results also show that persons who lived in the old urban areas received more support than did their counterparts in the new towns and older persons who lived in public housing received more objective informal support than those who lived in private housing. The implications of the findings for policy towards older persons in Hong Kong and similar Asia-Pacific societies are discussed.

The impacts of dwelling conditions on older persons' psychological well-being in Hong Kong: the mediating role of residential satisfaction.

About 11% of Hong Kong's population of 7 million people are aged 65 and over and many of them live in old urban areas. Many of these areas have been subjected to urban redevelopment and some of the residents have been relocated to newer estates in peripheral new towns. Previous studies have focused on the challenges the urban environment has placed on older persons in terms of capability to cope with the demands that the environment places upon them. This paper suggests that dwelling conditions can act as stressors and become contributing factors that impact on older persons' residential satisfaction and psychological well-being (subjective well-being). This study examines the role of residential satisfaction (satisfaction with dwelling unit, estate and district) in mediating the effects of dwelling conditions (interior environment and exterior environment) on psychological well-being. A sample of older persons was recruited from a sampling frame of 16 urban sub-areas located in old urban areas and new towns. 518 older persons (224 males, 294 females) aged 60 and over were interviewed and the findings indicated that residential satisfaction was determined by assessment of both the interior environment and the exterior environment, although these were appraised differently. The interior environment had a greater impact on residential satisfaction than the exterior environment. It appeared that environmental dwelling conditions mainly affected older persons' psychological well-being indirectly and, hence, probably influenced their opportunities for successful ageing. However, subsequent tests revealed that dwelling conditions had no direct impact on psychological well-being. In light of these findings, it is proposed that the role of environmental factors and their relation to older persons' psychological well-being depends on the extent to which a person's expectations of residential satisfaction are met. Some implications of these findings for local housing and social care policy are discussed.