Simon Kingham

Mapping urban air pollution using GIS: a regression-based approach

As part of the EU-funded SAVIAH project, a regression-based methodology for mapping traffic-related air pollution was developed within a GIS environment. Mapping was carried out for NO2 in Amsterda...

A regression-based method for mapping traffic-related air pollution: application and testing in four contrasting urban environments.

Accurate, high-resolution maps of traffic-related air pollution are needed both as a basis for assessing exposures as part of epidemiological studies, and to inform urban air-quality policy and traffic management. This paper assesses the use of a GIS-based, regression mapping technique to model spatial patterns of traffic-related air pollution. The model--developed using data from 80 passive sampler sites in Huddersfield, as part of the SAVIAH (Small Area Variations in Air Quality and Health) project--uses data on traffic flows and land cover in the 300-m buffer zone around each site, and altitude of the site, as predictors of NO2 concentrations. It was tested here by application in four urban areas in the UK: Huddersfield (for the year following that used for initial model development), Sheffield, Northampton, and part of London. In each case, a GIS was built in ArcInfo, integrating relevant data on road traffic, urban land use and topography. Monitoring of NO2 was undertaken using replicate passive samplers (in London, data were obtained from surveys carried out as part of the London network). In Huddersfield, Sheffield and Northampton, the model was first calibrated by comparing modelled results with monitored NO2 concentrations at 10 randomly selected sites; the calibrated model was then validated against data from a further 10-28 sites. In London, where data for only 11 sites were available, validation was not undertaken. Results showed that the model performed well in all cases. After local calibration, the model gave estimates of mean annual NO2 concentrations within a factor of 1.5 of the actual mean (approx. 70-90%) of the time and within a factor of 2 between 70 and 100% of the time. r2 values between modelled and observed concentrations are in the range of 0.58-0.76. These results are comparable to those achieved by more sophisticated dispersion models. The model also has several advantages over dispersion modelling. It is able, for example, to provide high-resolution maps across a whole urban area without the need to interpolate between receptor points. It also offers substantially reduced costs and processing times compared to formal dispersion modelling. It is concluded that the model might thus be used as a means of mapping long-term air pollution concentrations either in support of local authority air-quality management strategies, or in epidemiological studies.

Improving health through policies that promote active travel: A review of evidence to support integrated health impact assessment

BACKGROUND Substantial policy changes to control obesity, limit chronic disease, and reduce air pollution emissions, including greenhouse gasses, have been recommended. Transportation and planning policies that promote active travel by walking and cycling can contribute to these goals, potentially yielding further co-benefits. Little is known, however, about the interconnections among effects of policies considered, including potential unintended consequences. OBJECTIVES AND METHODS We review available literature regarding health impacts from policies that encourage active travel in the context of developing health impact assessment (HIA) models to help decision-makers propose better solutions for healthy environments. We identify important components of HIA models of modal shifts in active travel in response to transport policies and interventions. RESULTS AND DISCUSSION Policies that increase active travel are likely to generate large individual health benefits through increases in physical activity for active travelers. Smaller, but population-wide benefits could accrue through reductions in air and noise pollution. Depending on conditions of policy implementations, risk tradeoffs are possible for some individuals who shift to active travel and consequently increase inhalation of air pollutants and exposure to traffic injuries. Well-designed policies may enhance health benefits through indirect outcomes such as improved social capital and diet, but these synergies are not sufficiently well understood to allow quantification at this time. CONCLUSION Evaluating impacts of active travel policies is highly complex; however, many associations can be quantified. Identifying health-maximizing policies and conditions requires integrated HIAs.

Travelling to work: will people move out of their cars?

This paper examines employees perceptions of their modal choice during the journey to work, and addresses what factors influence modal choice, and whether people can be moved out of their cars to other more sustainable forms of transport. The results of surveys of the commuting habits of employees at two UK companies are presented and compared with other relevant studies. Ninety-seven and 88% of staff at the respective companies travel to work by car. While only 2 and 7% of respondents cycled to work, real potential for cycling was identified, given improvements in the cycling infrastructure. Similarly, while only 0 and 3% currently use public transport for the journey to work, improved services could see a significant modal shift. Overall, there seemed to be genuine willingness to move out of the car for the journey to work, with one of the main barriers being a perception that the alternatives are not viable. Additionally, it appears many people live too far from the workplace to cycle or use public transport.

Role of physical activity in the relationship between urban green space and health

OBJECTIVES Local availability of green space has been associated with a wide range of health benefits. Possible causative mechanisms underpinning the green space and health relationship include the provision of physical activity opportunities, the stress-relieving effects of nature and the facilitation of social contacts. This study sought to investigate whether urban green space was related to individual-level health outcomes, and whether levels of physical activity were likely to be a mediating factor in any relationships found. STUDY DESIGN Cross-sectional analysis of anonymized individual health survey responses. METHODS Neighbourhood-level green space availability was linked to 8157 respondents to the New Zealand Health Survey 2006/07 on the basis of their place of residence. Adjusted multilevel models were constructed for four health outcomes which are plausibly related to green space via physical activity: cardiovascular disease; overweight; poor general health; and poor mental health (Short Form 36). RESULTS The greenest neighbourhoods had the lowest risks of poor mental health [odds ratio (OR) 0.81, 95% confidence interval (CI) 0.66-1.00]. Cardiovascular disease risk was reduced in all neighbourhoods with >15% green space availability (e.g. OR 0.80, 95% CI 0.64-0.99 for those with 33-70% green space), However, a dose-response relationship was not found. Green space availability was not related to overweight or poor general health. Overall, levels of physical activity were higher in greener neighbourhoods, but adjustment for this only slightly attenuated the green space and health relationships. CONCLUSIONS Neighbourhood green space was related to better cardiovascular and mental health in a New Zealand Health Survey, independent of individual risk factors. Although physical activity was higher in greener neighbourhoods, it did not fully explain the green space and health relationship.

EMPLOYER TRAVEL PLANS, CYCLING AND GENDER: WILL TRAVEL PLAN MEASURES IMPROVE THE OUTLOOK FOR CYCLING TO WORK IN THE UK?

Abstract Cycling is a ‘green’ alternative to commuting by car yet it makes up only a small percentage of journeys in the UK. Here we examine the commuter habits of three companies in Hertfordshire, UK. These provide contrasting case studies allowing examination of travel behaviour in relation to gender and employer travel plans. Women are known to commute shorter distances, yet are less likely to cycle. A variety of cultural and trip characteristics can account for this yet more detailed analysis reveals that some generalisations do not apply. Organisational initiatives to increase cycle commuting were perceived more positively by men than women and this suggests provision of cycling facilities in travel plans will not be effective for organisations employing a large proportion of women. However, this hides a subgroup of women who have access to a cycle and live near enough to cycle who are more positive about cycle facilities. A variety of cultural and societal constraints on cycle use are considered. Measures to encourage cycling in employer travel plans must reflect the gender balance in the organisation as well as recognised geographical and organisational factors.

The association between green space and cause-specific mortality in urban New Zealand: an ecological analysis of green space utility

BackgroundThere is mounting international evidence that exposure to green environments is associated with health benefits, including lower mortality rates. Consequently, it has been suggested that the uneven distribution of such environments may contribute to health inequalities. Possible causative mechanisms behind the green space and health relationship include the provision of physical activity opportunities, facilitation of social contact and the restorative effects of nature. In the New Zealand context we investigated whether there was a socioeconomic gradient in green space exposure and whether green space exposure was associated with cause-specific mortality (cardiovascular disease and lung cancer). We subsequently asked what is the mechanism(s) by which green space availability may influence mortality outcomes, by contrasting health associations for different types of green space.MethodsThis was an observational study on a population of 1,546,405 living in 1009 small urban areas in New Zealand. A neighbourhood-level classification was developed to distinguish between usable (i.e., visitable) and non-usable green space (i.e., visible but not visitable) in the urban areas. Negative binomial regression models were fitted to examine the association between quartiles of area-level green space availability and risk of mortality from cardiovascular disease (n = 9,484; 1996 - 2005) and from lung cancer (n = 2,603; 1996 - 2005), after control for age, sex, socio-economic deprivation, smoking, air pollution and population density.ResultsDeprived neighbourhoods were relatively disadvantaged in total green space availability (11% less total green space for a one standard deviation increase in NZDep2001 deprivation score, p < 0.001), but had marginally more usable green space (2% more for a one standard deviation increase in deprivation score, p = 0.002). No significant associations between usable or total green space and mortality were observed after adjustment for confounders.ConclusionContrary to expectations we found no evidence that green space influenced cardiovascular disease mortality in New Zealand, suggesting that green space and health relationships may vary according to national, societal or environmental context. Hence we were unable to infer the mechanism in the relationship. Our inability to adjust for individual-level factors with a significant influence on cardiovascular disease and lung cancer mortality risk (e.g., diet and alcohol consumption) will have limited the ability of the analyses to detect green space effects, if present. Additionally, green space variation may have lesser relevance for health in New Zealand because green space is generally more abundant and there is less social and spatial variation in its availability than found in other contexts.

An ecological study investigating the association between access to urban green space and mental health

OBJECTIVES This study aims to find whether proximity to urban green spaces is associated with human mental health. STUDY DESIGN A cross-sectional examination of the relationship between access to urban green spaces and counts of anxiety/mood disorder treatments amongst residents (aged 15 years and over) in Auckland City, New Zealand. METHODS Anxiety/mood disorder treatment counts by three age groups were aggregated to 3149 small area units in Auckland. Six measures of green space access were derived using GIS techniques involving total green spaces and useable green spaces. Negative binomial regression models have been fitted to test the relationship between access to green space and area-level anxiety/mood disorder treatment counts, adjusted for age and area-level deprivation. RESULTS Anxiety/mood disorder treatment counts were associated with three green space measures. The proportion of both total and useable green space within 3 km and distance to nearest useable green space all indicated a protective effect of increased access to green space against anxiety/mood disorder treatment counts. Access to total and useable green space within 300 m did not exhibit significant associations. CONCLUSION This study found that decreased distance to useable green space and increased proportion of green space within the larger neighbourhood were associated with decreased anxiety/mood disorder treatment counts in an urban environment. This suggests the benefits of green space on mental health may relate both to active participation in useable green spaces near to the home and observable green space in the neighbourhood environment.

The effect of ambient air pollution on respiratory health of school children: a panel study.

BackgroundAdverse respiratory effects of particulate air pollution have been identified by epidemiological studies. We aimed to examine the health effects of ambient particulate air pollution from wood burning on school-age students in Christchurch, New Zealand, and to explore the utility of urine and exhaled breath condensate biomarkers of exposure in this population.MethodsA panel study of 93 male students (26 with asthma) living in the boarding house of a metropolitan school was undertaken in the winter of 2004. Indoor and outdoor pollution data was continuously monitored. Longitudinal assessment of lung function (FEV1 and peak flow) and symptoms were undertaken, with event studies of high pollution on biomarkers of exposure (urinary 1-hydroxypyrene) and effect (exhaled breath condensate (EBC) pH and hydrogen peroxide concentration).ResultsPeak levels of air pollution were associated with small but statistically significant effects on lung function in the asthmatic students, but not healthy students. No significant effect of pollution could be seen either on airway inflammation and oxidative stress either in healthy students or students with asthma. Minor increases in respiratory symptoms were associated with high pollution exposure. Urinary 1-hydroxypyrene levels were raised in association with pollution events by comparison with low pollution control days.ConclusionThere is no significant effect of ambient wood-smoke particulate air pollution on lung function of healthy school-aged students, but a small effect on respiratory symptoms. Asthmatic students show small effects of peak pollution levels on lung function. Urinary 1-hydroxypyrene shows potential as a biomarker of exposure to wood smoke in this population; however measurement of EBC pH and hydrogen peroxide appears not to be useful for assessment of population health effects of air pollution.Some of the data presented in this paper has previously been published in Kingham and co-workers Atmospheric Environment, 2006 Jan; 40: 338–347 (details of pollution exposure), and Cavanagh and co-workers Sci Total Environ. 2007 Mar 1;374(1):51-9 (urine hydroxypyrene data).

ASSESSMENT OF EXPOSURE TO TRAFFIC-RELATED FUMES DURING THE JOURNEY TO WORK

Abstract A pilot study was carried out to assess the levels of traffic related pollution individuals are exposed to while using different modes of transport on a typical journey to work route. This was carried out during the daily journey to work, and compared train, bus, car and bicycle (the latter both on the road and on an exclusive cycle path). The project monitored for benzene and inhalable particulates in September and October 1996. The car driver’s exposure was on all occasions the highest for benzene and the first or second highest for particulates compared to the other modes. The cyclists on the cycle path had in most cases the lowest or second lowest exposure to both pollutants. The road modes of transport always had the highest exposures to benzene. The cyclists on the road were exposed to significantly greater levels of both benzene and particulates than the cyclists on the path. There was large daily variation in levels of pollution exposure. This correlated with wind speed—the lower the wind speed the higher the levels of pollution. Based on the results of this pilot study tentative policy recommendations can be made. Public awareness should be raised concerning the potential pollution exposures by transport mode. Public transport should be promoted on the basis of low personal pollution exposure. To reduce cyclists’ pollution exposure, cycle paths should, wherever possible, be located away from main roads.