Kim N. Dirks

Evaluating the impact of wind turbine noise on health-related quality of life

We report a cross-sectional study comparing the health-related quality of life (HRQOL) of individuals residing in the proximity of a wind farm to those residing in a demographically matched area sufficiently displaced from wind turbines. The study employed a nonequivalent comparison group posttest-only design. Self-administered questionnaires, which included the brief version of the World Health Organization quality of life scale, were delivered to residents in two adjacent areas in semirural New Zealand. Participants were also asked to identify annoying noises, indicate their degree of noise sensitivity, and rate amenity. Statistically significant differences were noted in some HRQOL domain scores, with residents living within 2 km of a turbine installation reporting lower overall quality of life, physical quality of life, and environmental quality of life. Those exposed to turbine noise also reported significantly lower sleep quality, and rated their environment as less restful. Our data suggest that wind farm noise can negatively impact facets of HRQOL.

Exploring the Relationship between Noise Sensitivity, Annoyance and Health-Related Quality of Life in a Sample of Adults Exposed to Environmental Noise

The relationship between environmental noise and health is poorly understood but of fundamental importance to public health. This study estimated the relationship between noise sensitivity, noise annoyance and health-related quality of life in a sample of adults residing close to the Auckland International Airport, New Zealand. A small sample (n = 105) completed surveys measuring noise sensitivity, noise annoyance, and quality of life. Noise sensitivity was associated with health-related quality of life; annoyance and sleep disturbance mediated the effects of noise sensitivity on health.

The influence of vegetation on the horizontal and vertical distribution of pollutants in a street canyon.

Space constraints in cities mean that there are only limited opportunities for increasing tree density within existing urban fabric and it is unclear whether the net effect of increased vegetation in street canyons is beneficial or detrimental to urban air quality at local scales. This paper presents data from a field study undertaken in Auckland, New Zealand designed to determine the local impact of a deciduous tree canopy on the distribution of the oxides of nitrogen within a street canyon. The results showed that the presence of leaves on the trees had a marked impact on the transport of pollutants and led to a net accumulation of pollutants in the canyon below the tree tops. The incidence and magnitude of temporally localised spikes in pollutant concentration were reduced within the tree canopy itself. A significant difference in pollutant concentrations with height was not observed when leaves were absent. Analysis of the trends in concentration associated with different wind directions showed a smaller difference between windward and leeward sides when leaves were on the trees. A small relative increase in concentrations on the leeward side was observed during leaf-on relative to leaf-off conditions as predicted by previous modelling studies. However the expected reduction in concentrations on the windward side was not observed. The results suggest that the presence of leaves on the trees reduces the upwards transport of fresh vehicle emissions, increases the storage of pollutants within the canopy space and reduces the penetration of clean air downwards from aloft. Differences observed between NO and NO(2) concentrations could not be accounted for by dispersion processes alone, suggesting that there may also be some changes in the chemistry of the atmosphere associated with the presence of leaves on the trees.

Health and climate related ecosystem services provided by street trees in the urban environment

Urban tree planting initiatives are being actively promoted as a planning tool to enable urban areas to adapt to and mitigate against climate change, enhance urban sustainability and improve human health and well-being. However, opportunities for creating new areas of green space within cities are often limited and tree planting initiatives may be constrained to kerbside locations. At this scale, the net impact of trees on human health and the local environment is less clear, and generalised approaches for evaluating their impact are not well developed.In this review, we use an urban ecosystems services framework to evaluate the direct, and locally-generated, ecosystems services and disservices provided by street trees. We focus our review on the services of major importance to human health and well-being which include ‘climate regulation’, ‘air quality regulation’ and ‘aesthetics and cultural services’. These are themes that are commonly used to justify new street tree or street tree retention initiatives. We argue that current scientific understanding of the impact of street trees on human health and the urban environment has been limited by predominantly regional-scale reductionist approaches which consider vegetation generally and/or single out individual services or impacts without considering the wider synergistic impacts of street trees on urban ecosystems. This can lead planners and policymakers towards decision making based on single parameter optimisation strategies which may be problematic when a single intervention offers different outcomes and has multiple effects and potential trade-offs in different places.We suggest that a holistic approach is required to evaluate the services and disservices provided by street trees at different scales. We provide information to guide decision makers and planners in their attempts to evaluate the value of vegetation in their local setting. We show that by ensuring that the specific aim of the intervention, the scale of the desired biophysical effect and an awareness of a range of impacts guide the choice of i) tree species, ii) location and iii) density of tree placement, street trees can be an important tool for urban planners and designers in developing resilient and resourceful cities in an era of climatic change.

A semi-empirical model for predicting the effect of changes in traffic flow patterns on carbon monoxide concentrations

A simple semi-empirical model for predicting the effect of changes in traffic flow patterns on carbon monoxide concentrations is presented. The traffic component of the model requires average vehicle emission rate estimates for a range of driving conditions, as well as traffic flow data for the site of interest. The dispersion component of the model is based on a modified empirically optimised box model requiring only wind speed and direction information. The model is evaluated at a suburban site in Hamilton, New Zealand. Despite the simplicity of the model, produces reliable concentration predictions when tested on days with significantly different traffic flow patterns from those days with which the optimum model parameters were evaluated.

Do quiet areas afford greater health-related quality of life than noisy areas?

People typically choose to live in quiet areas in order to safeguard their health and wellbeing. However, the benefits of living in quiet areas are relatively understudied compared to the burdens associated with living in noisy areas. Additionally, research is increasingly focusing on the relationship between the human response to noise and measures of health and wellbeing, complementing traditional dose-response approaches, and further elucidating the impact of noise and health by incorporating human factors as mediators and moderators. To further explore the benefits of living in quiet areas, we compared the results of health-related quality of life (HRQOL) questionnaire datasets collected from households in localities differentiated by their soundscapes and population density: noisy city, quiet city, quiet rural, and noisy rural. The dose-response relationships between noise annoyance and HRQOL measures indicated an inverse relationship between the two. Additionally, quiet areas were found to have higher mean HRQOL domain scores than noisy areas. This research further supports the protection of quiet locales and ongoing noise abatement in noisy areas.

Personal Exposure to Air Pollution for Various Modes of Transport in Auckland, New Zealand

This paper investigates the carbon monoxide (CO) doses received while commuting by different modes (car, bus, train, motorcycle, bicycle and running), taking into account the commute time as well as the level of physical activity required. While the participants were constrained to travel at specific peak traffic times and between designated start and end points, they were free to choose a route appropriate for their mode of transport. The results of this study suggest that the lowest exposures (concentrations of pollutants) are experienced by train commuters, largely a reflection of the routes being removed from any significant road traffic. Motorcyclists experienced significantly higher average concentrations as a result of high-concentration and very-short-duration peaks not seen in the traces of car and bus commuters travelling on the same road. Travel by bus along a dedicated busway was also found to be effective in reducing commuter air pollution exposure compared to travel by car on a congested stretch of motorway. The average concentrations to which cyclists and runners were exposed were found to be not significantly different for those travelling by car or bus (except when on dedicated pedestrian/cycleways). However, when the increased physical activity that is required is taken into account (leading to higher volumes of air breathed) along with the increased commuting time (especially in the case of runners), the air pollution doses (as estimated by the product of the concentration, commute time and breathing factor) were found to be significantly higher than for the motorised modes. The results suggest that separate pedestrian/cycleways go some way towards providing healthier options for cyclists and pedestrians.

Road traffic noise and health-related quality of life: A cross-sectional study

Evidence is emerging linking environmental noise to health problems. Noise can affect health directly and indirectly: For example, noise sensitivity moderates the effects of noise annoyance, which in turn mediates the effects of noise exposure. An alternative hypothesis is that noise sensitivity marks the presence of susceptibility to health problems in general, including annoyance from noise. Whether noise sensitivity causes poor health or whether it is a marker of susceptibility to health problems was addressed by comparing the results of a community-based survey of people with similar noise sensitivity profiles but different environmental noise exposures. A questionnaire was delivered to people living in two socio-economically-matched areas: One was within 50 m of a motorway and the other was away from any significant source of environmental noise. The questionnaire contained 58 questions comprised of the World Health Organization health-related quality of life questionnaire (WHOQOL), and questions about amenity, neighborhood issues, environmental annoyances, demographics, and noise sensitivity. Noise sensitivity did not vary with proximity to the motorway but annoyance with traffic noise and fumes was greater in those living close to the motorway than in those who were not. Scores on the four WHOQOL domains (physical, psychological, social, and environmental) were lower in those living close to the motorway, and the WHOQOL domain scores correlated negatively with noise sensitivity in those who lived near motorways but not in those who lived in the quieter areas. This suggests that noise sensitivity is related to poor health outcomes rather than being a trait marker of susceptibility to health problems in general.

Indoor Air Pollution Levels Were Halved as a Result of a National Tobacco Ban in a New Zealand Prison

INTRODUCTION Few studies have measured the effect of tobacco bans on secondhand smoke (SHS) exposure in prisons. From June 1, 2011, the sale of tobacco was prohibited in New Zealand prisons. One month later, the possession of tobacco was banned. We studied the indoor air quality before and after this policy was enforced. METHODS We measured indoor-fine-particulate (PM(2.5)) concentrations using a TSI SidePak photometer. The instrument was placed in a staff base of a New Zealand maximum-security prison, adjacent to four 12-cell wings. Measurements were made before the sales restriction, during this period, and after the ban. Data were summarized using daily geometric means and generalized least squares regression. RESULTS A total of 7,107 observations were recorded at 5-min intervals, on 14 days before and 15 days after implementation, between 24 May and 5 August. Before the policy was implemented, the geometric mean was 6.58 μg/m(3) (95% CI = 6.29-6.58), which declined to 5.17 μg/m(3) (95% CI = 4.93-5.41) during the sales ban, and fell to 2.44 μg/m(3) (95% CI = 2.37-2.52) after the smoking ban. Regression analyses revealed an average 57% (95% CI = 42-68) decline in PM(2.5) concentrations, comparing the before and after periods. CONCLUSIONS Our study showed a rapid and substantial improvement in indoor air quality after tobacco was banned at a prison. We conclude that prisoners have reduced their smoking in line with the ban, and that a significant health hazard has been reduced for staff and prisoners alike.

A simple semi-empirical model for predicting missing carbon monoxide concentrations

Carbon monoxide monitoring using continuous samplers is carried out in most major urban centres in the world and generally forms the basis for air quality assessments. Such assessments become less reliable as the proportion of data missing due to equipment failure and periods of calibration increases. This paper presents a semi-empirical model for the prediction of atmospheric carbon monoxide concentrations near roads for the purpose of interpolating missing data without the need for any traffic or emissions information. The model produces reliable predictions while remaining computationally simple by being site-specifically optimized. The model was developed for, and evaluated at, both a suburban site and an inner city site in Hamilton, New Zealand. Model performance statistics were found to be significantly better than other simple methods of interpolation with little additional computational complexity.