Long-term exposure to PM2.5 air pollution and mental health: a retrospective cohort study in Ireland.

BACKGROUND: Mental illness is the leading cause of years lived with disability, and the global disease burden of mental ill-health has increased substantially in the last number of decades. There is now increasing evidence that environmental conditions, and in particular poor air quality, may be associated with mental health and wellbeing. METHODS: This cross-sectional analysis uses data on mental health and wellbeing from The Irish Longitudinal Study on Ageing (TILDA), a nationally representative survey of the population aged 50+ in Ireland. Annual average PM2.5 concentrations at respondents' residential addresses over the period 1998-2014 are used to measure long-term exposure to ambient PM2.5. RESULTS: We find evidence of associations between long-term exposure to ambient PM2.5 and depression and anxiety. The measured associations are strong, and are comparable with effect sizes for variables such as sex. Effects are also evident at relatively low concentrations by international standards. However, we find no evidence of associations between long-term ambient particulate pollution and other indicators of mental health and well-being such as stress, worry and quality of life. CONCLUSIONS: The measured associations are strong, particularly considering the relatively low PM2.5 concentrations prevailing in Ireland compared to many other countries. While it is estimated that over 90 per cent of the world's population lives in areas with annual mean PM2.5 concentrations greater than 10 µg/m3, these results contribute to the increasing evidence that suggests that harmful effects can be detected at even low levels of air pollution.

Local NO2 concentrations and asthma among over-50s in Ireland: A microdata analysis.

BACKGROUND: Links between air pollution and asthma are less well established for older adults than some younger groups. Nitrogen dioxide (NO2) concentrations are widely used as an indicator of transport-related air pollution, and some literature suggests NO2 may directly affect asthma. METHODS: This study used data on 8162 adults >50 years old in the Republic of Ireland to model associations between estimated annual outdoor concentration of NO2 and the probability of having asthma. Individual-level geo-coded survey data from The Irish Longitudinal Study on Ageing (TILDA) were linked to model-based estimates of annual average NO2 at 50 m resolution. Asthma was identified using two methods: self-reported diagnoses and respondents' use of medications related to obstructive airway diseases. Logistic regressions were used to model the relationships. RESULTS: NO2 concentrations were positively associated with the probability of asthma [marginal effect (ME) per 1 ppb of airborne NO2 = 0.24 percentage points asthma self-report, 95% confidence interval (CI) 0.06-0.42, mean asthma prevalence 0.09; for use of relevant medications ME = 0.21 percentage points, 95% CI 0.049-0.37, mean prevalence 0.069]. Results were robust to varying model specification and time period. Respondents in the top fifth percentile of NO2 exposure had a larger effect size but also greater standard error (ME = 2.4 percentage points asthma self-report, 95% CI -0. 49 to 5.3). CONCLUSIONS: Associations between local air pollution and asthma among older adults were found at relatively low concentrations. To illustrate this, the marginal effect of an increase in annual average NO2 concentration from sample minimum to median (2.5 ppb) represented about 7-8% of the sample average prevalence of asthma.

Demographic variation in active consumer behaviour: On-line search for retail broadband services.

Consumers who actively search for better broadband deals may benefit from lower prices or improved service quality compared to those who do not. If, however, consumers differ in their propensity to engage with the market and actively search, these potential benefits may not accrue equally. This paper investigates differences in consumer search activity for telecommunications services across small geographic areas. We exploit rich and novel data from a commercial price comparison site to explore the dispersion of consumer search in the Irish retail broadband market, while controlling for supply-side variations. By linking geo-coded searches to census data on small area socio-economic characteristics, we identify the areas where most search originates and can thus characterise the socio-economic groups to whom the benefits of search are most likely to accrue. We find evidence that areas populated by many highly educated, married people, commuters, mortgage holders, and retirees are among the most active in search. In contrast, those areas in which many older people, farmers, low-skilled workers and students reside give rise to significantly fewer consumer searches.

Characterising urban green space density and footpath-accessibility in models of BMI.

BACKGROUND: While exposure to urban green spaces has been associated with various physical health benefits, the evidence linking these spaces to lower BMI, particularly among older people, is mixed. We ask whether footpath availability, generally unobserved in the existing literature, may mediate exposure to urban green space and help explain this volatility in results. The aim of this study is to add to the literature on the association between urban green space and BMI by considering alternative measures of urban green space that incorporate measures of footpath availability. METHODS: We conduct a cross-sectional study combining data from The Irish Longitudinal Study on Ageing and detailed land use information. We proxy respondents' exposure to urban green spaces at their residential addresses using street-side and area buffers that take account of the presence of footpaths. Generalised linear models are used to test the association between exposure to several measures of urban green space and BMI. RESULTS: Relative to the third quintile, exposure to the lowest quintile of urban green space, as measured within a 1600 m footpath-accessible network buffer, is associated with slightly higher BMI (marginal effect: 0.80; 95% CI: 0.16-1.44). The results, however, are not robust to small changes in how green space is measured and no statistically significant association between urban green spaces and BMI is found under other variants of our regression model. CONCLUSION: The relationship between urban green spaces and BMI among older adults is highly sensitive to the characterisation of local green space. Our results suggest that there are some unobserved factors other than footpath availability that mediate the relationship between urban green spaces and weight status.