This study aimed to investigate various aspects of cyclist exposure to common urban air pollutants, including CO, PM10, PM2.5, PM1.0 and UFPs. The initial part of the study compared cyclist exposure to that of other transport modes, while the second part addressed the implications of route choice. The final part analysed the effect of proximity to traffic. Data was collected in Christchurch and Auckland cities over a nine week period, with a total of 53 inter-modal and 7 separate cyclist sampling runs completed. Mobile sampling was conducted using a collection of instruments in four portable kits. Fixed-site meteorological data was used to find associations between pollutants and temperature and wind speed. Spatial patterns were also considered by means of time-series comparative graphs and colour-coded pollutant concentration GPS mapping. The cyclist mode was up to 61% less exposed than the car for primary pollutants (CO and UFPs), but up to 26% more exposed for PM1.0-10. The bus was generally the most exposed for all pollutants apart from CO. The effect of route choice was substantial, with the off-road cyclist route recording a reduction of 31% for CO and PM1.0, and 53% for UFPs while PM10 was 6%. At a distance of 7 m from traffic, exposure dropped by 30% (UFPs), 22% (CO) and 14% (PM2.5). At 19 m, concentrations decreased a further 17%, 13% and 8%, respectively. When moving much further away from traffic (~700 m), the effect was far less pronounced and no difference was observed for CO past 19 m. Conclusions suggest that for most pollutants studied, the cyclist mode faces much lower exposure than other modes, especially when traveling through backstreets and cycle tracks. Significant exposure reductions can also be made when only a very small distance away from traffic emissions. This has positive implications for health, sustainable city planning and active-mode transport promotion.

This study aimed to investigate various aspects of cyclist exposure to common urban air pollutants, including CO, PM10, PM2.5, PM1.0 and UFPs. The initial part of the study compared cyclist exposure to that of other transport modes, while the second part addressed the implications of route choice. The final part analysed the effect of proximity to traffic. Data was collected in Christchurch and Auckland cities over a nine week period, with a total of 53 inter-modal and 7 separate cyclist sampling runs completed. Mobile sampling was conducted using a collection of instruments in four portable kits. Fixed-site meteorological data was used to find associations between pollutants and temperature and wind speed. Spatial patterns were also considered by means of time-series comparative graphs and colour-coded pollutant concentration GPS mapping. The cyclist mode was up to 61% less exposed than the car for primary pollutants (CO and UFPs), but up to 26% more exposed for PM1.0-10. The bus was generally the most exposed for all pollutants apart from CO. The effect of route choice was substantial, with the off-road cyclist route recording a reduction of 31% for CO and PM1.0, and 53% for UFPs while PM10 was 6%. At a distance of 7 m from traffic, exposure dropped by 30% (UFPs), 22% (CO) and 14% (PM2.5). At 19 m, concentrations decreased a further 17%, 13% and 8%, respectively. When moving much further away from traffic (~700 m), the effect was far less pronounced and no difference was observed for CO past 19 m. Conclusions suggest that for most pollutants studied, the cyclist mode faces much lower exposure than other modes, especially when traveling through backstreets and cycle tracks. Significant exposure reductions can also be made when only a very small distance away from traffic emissions. This has positive implications for health, sustainable city planning and active-mode transport promotion.

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Asthma is the most common chronic disease in children and the effects of air pollution exposure on asthma and respiratory health in children have been a growing concern over recent decades. Although a number of epidemiological studies have been carried out in this field, these have produced conflicting results. The aim of this study was to assess the effects of long term exposure to nitrogen dioxide (NO2) and particulate matter (PM10) on asthma prevalence and lung function in children. To achieve this, a novel exposure model was developed and evaluated, which allowed retrospective exposure assessment of children participating in a population based birth cohort study – the Manchester Asthma and Allergy Study (MAAS). MAAS is a prospective birth cohort study comprising 1185 children specifically designed to study asthma and allergies. Clinical follow up took place at ages 3, 5, 8 and 11 years. At each follow up parents completed questionnaires on asthma diagnosis and symptoms and children underwent skin prick tests for common allergens. Children’s specific airways resistance (sRaw, at ages 3, 5, 8, 11) and forced expiratory volume in one second (FEV1, at ages 5, 8, 11) were measured. At ages 5 and 11 years FEV1 was measured at baseline and after bronchodilator treatment. The exposure model developed during this study incorporated outdoor and indoor air pollution, spatio-temporal variation in air pollution and time-activity patterns of children. The model was based on the concept of microenvironmental exposure. It modelled personal exposure based on PM10 and NO2 concentrations in children’s home, school and journey microenvironments (MEs) and the length of time they spend in these MEs. Land use regression (LUR) models were used to model PM10 and NO2 concentrations in outdoor MEs. These LUR models were specifically developed for the Greater Manchester area. A novel method was used to develop the LUR models, which used the output from an air dispersion model as dependent variables in the regression analysis. Furthermore, a novel approach was used to obtain annual concentration of PM10 and NO2 from 1996 to 2010, which involved the recalibration of the LUR models for each year. A mass balance model and indoor to outdoor ratios were used to model concentrations in indoor MEs. The performance of the exposure model was evaluated through a personal monitoring study in schoolchildren attending a local secondary school. Children wore personal NO2 monitors for two consecutive days in four seasons. Parental questionnaires and time-activity diaries were used to obtain information for the exposure model and to model NO2 exposure for the same time period. The results showed good agreement between monitored and modelled NO2 concentrations (Normalised mean bias factor=-0.04). Multiple linear regression and generalised estimating equations (GEE) were used to assess the cross-sectional and longitudinal effect of modelled exposure on sRaw and FEV1 (as % predicted). Multiple logistic regression and GEE were used to assess the effect of modelled exposure on the prevalence of asthma and current wheeze.The longitudinal analyses showed significant associations between PM10 and NO2 exposure and % predicted FEV1 (PM10: B=-1.37, p=0.019; NO2: B=-0.83, p=0.003), but no association with sRaw (PM10: B=0.009, p=0.37; NO2: B=-0.007, p=0.16). The cross-sectional analyses showed no association between pollutant exposure during the summer or winter prior to age 11 and any of the lung function measures (p>0.05). Long term PM10 or NO2 exposure were not associated with asthma or current wheeze (p>0.05).This study developed and evaluated a novel air pollution exposure model for epidemiological research. The results of this study suggest a negative impact of long term exposure to NO2 and PM10 on growth in FEV1 during primary school age. However, no evidence of an association between long term exposure to NO2 and PM10 and childhood asthma was found.

Increasing vehicle dependence in the United States has resulted in substantial emissions of traffic-related air pollutants that contribute to the deterioration of urban air quality. Exposure to urban air pollutants trigger a number of public health concerns, including the potential of inequality of exposures and health effects among population subgroups. To better understand the impact of traffic-related pollutants on air quality, exposure, and exposure inequality, modeling methods that can appropriately characterize the spatiotemporally resolved concentration distributions of traffic-related pollutants need to be improved. These modeling methods can then be used to investigate the impacts of urban design and transportation management choices on air quality, pollution exposures, and related inequality. This work will address these needs with three objectives: 1) to improve modeling methods for investigating interactions between city and transportation design choices and air pollution exposures, 2) to characterize current exposures and the social distribution of exposures to traffic-related air pollutants for the case study area of Hillsborough County, Florida, and 3) to determine expected impacts of urban design and transportation management choices on air quality, air pollution exposures, and exposure inequality. To achieve these objectives, the impacts of a small-scale transportation management project, specifically the '95 Express' high occupancy toll lane project, on pollutant emissions and nearby air quality was investigated. Next, a modeling method capable of characterizing spatiotemporally resolved pollutant emissions, concentrations, and exposures was developed and applied to estimate the impact of traffic-related pollutants on exposure and exposure inequalities among several population subgroups in Hillsborough County, Florida. Finally, using these results as baseline, the impacts of sprawl and compact urban forms, as well as vehicle fleet electrification, on air quality, pollution exposure, and exposure inequality were explored. Major findings include slightly higher pollutant emissions, with the exception of hydrocarbons, due to the managed lane project. Results also show that ambient concentration contributions from on-road mobile sources are disproportionate to their emissions. Additionally, processes not captured by the CALPUFF model, such as atmospheric formation, contribute substantially to ambient concentration levels of the secondary pollutants such as acetaldehyde and formaldehyde. Exposure inequalities for NOx, 1,3-butadiene, and benzene air pollution were found for black, Hispanic, and low income (annual household income less than $20,000) subgroups at both short-term and long-term temporal scales, which is consistent with previous findings. Exposure disparities among the subgroups are complex, and sometimes reversed for acetaldehyde and formaldehyde, due primarily to their distinct concentration distributions. Compact urban form was found to result in lower average NOx and benzene concentrations, but higher exposure for all pollutants except for NOx when compared to sprawl urban form. Evidence suggests that exposure inequalities differ between sprawl and compact urban forms, and also differ by pollutants, but are generally consistent at both short and long-term temporal scales. In addition, vehicle fleet electrification was found to result in generally lower average pollutant concentrations and exposures, except for NOx. However, the elimination of on-road mobile source emissions does not substantially reduce exposure inequality. Results and findings from this work can be applied to assist transportation infrastructure and urban planning. In addition, method developed here can be applied elsewhere for better characterization of air pollution concentrations, exposure and related inequalities.