Chapter 1.This chapter investigates the direct behavioral impact of information-based regulations by examining the effect of ozone alerts on cycling trips in Sydney. Moreover, the dynamics of individuals' response is studied by examining the behavioral impact of two successive day ozone alerts on cycling demand. A common problem in estimating direct avoidance behavior is that an increase in the pollution level could be an endogenous response to alerts. While controlling for the endogenous effect of alerts and air quality, results show that cycling trips decrease by 35 percent in response to a smog alert. When alerts are issued for two successive days, however, individuals appear to neglect the second day alerts. Our findings also indicate that ozone alerts induce one and half times larger impacts on weekends compared to weekdays. These patterns suggest that the cost of cycling substitution for commuter goals is higher than leisure goals. Furthermore, the cost of intertemporally avoiding cycling is increasing over time. Chapter 2. If decisions with lasting consequences are influenced by extraneous or transient factors then welfare can be damaged. This chapter investigates the impact of outdoor temperature on high-stakes decisions (immigration adjudications) made by professional decision-makers (US immigration judges). In our preferred specification, which includes spatial, temporal and judge fixed effects, and controls for various potential confounders, a 10 F degree increase in case-day temperature reduces positive decisions by 6.55%. This is despite judgements being made indoors, `protected' by climate-control. Results are consistent with established links from temperature to mood and risk appetite and have important implications for evaluating the welfare-burden of climate change. Chapter 3. The carbon tax in the Canadian province of British Columbia is widely-regarded as a `poster child' application of market-based methods to address greenhouse gas emissions. However the implications for local air quality have been ignored. Using synthetic control and difference-in-difference methods, in this chapter we evidence a causal link from carbon tax implementation and level to increased nitrogen oxides NOx and ultra-fine particulates PM_2.5 pollution problems in Vancouver, the province's largest city. We provide evidence consistent with the mechanism working through induced switching from gasoline to diesel vehicles. The results prove highly robust to inclusion of a wide set of controls in various combinations, alternative specifications, and satisfy a set of falsification checks. The analysis points to the possibility of negative secondary effects of climate policies, contrary to the usual presumption that secondary benefits are inevitably positive.

M.Sc. / This study is an investigation of environmental impacts caused by airborne fluorides around an industrial uranium and chemical facility in South Africa, the Necsa Pelindaba site. The literature study in Chapter 2 illustrates that industrial atmospheric fluoride emissions can have negative environmental impacts, including accumulation in surface soil horizons, necrosis in leaves, and fluorosis in plants and animals. Fluorides from this site are from two sources – stacks and evaporation pans. Samples to measure fluoride concentration in air, soil and vegetation and deposition rate were taken and analysed from February to August 2007. Standard analytical methods were used for the analysis of fluorides in all samples. Evaluation of historical environmental monitoring at Pelindaba showed that stack emissions were high in the year 2002 followed by a dramatic decrease in 2003 and 2004. In 2005, there was a sharp increase in emissions, with further slight increases until August 2007. For all media and sample types taken (air concentration, deposition, soil and vegetation), samples from nearby the evaporation pans had the highest fluoride concentrations. Results from sampling sites close to the stacks were lower, but still well above off-campus background sites, and above values from Pelindaba sites distant from the stacks. Fluoride concentrations in animal bones from previous studies done at the site showed enhanced fluoride concentrations compared to control samples. The project hypothesis was that fluoride emissions from Necsa Pelindaba site do not have a negative impact on the environment. This hypothesis is proven correct to the extent that no off-site adverse impacts or concentrations were observed. Limited on-campus impacts were observed localised around the evaporation pans and to a lesser extent around the stacks. Airborne fluoride concentration values around the pans only were above the South African guideline values. Deposition values were highest around the pans. The only visible leaf damage attributable to fluoride was on a Karee tree ~50 m from the edge of the pan. Soil fluoride concentrations from the current study were within the range of natural fluoride concentrations in soil. Despite evidence of local deposition, there was no evidence of fluoride accumulation in surface or subsurface soils. No impacts were observed elsewhere around the site or off-site. Based on the results of this work, fluoride emissions from the stacks do not pose a threat to the environment, provided that efficiency of the gas scrubbing equipment is maintained at current levels. Emissions from the pans pose a minor localised problem that nevertheless requires investigation and mitigation.

Over the past decade there has been a substantial increase in evidence suggesting an increased risk of adverse pregnancy outcomes from ambient air pollution exposure. However, there is yet to be enough convincing evidence to confirm a causal link between specific air pollutants and adverse pregnancy outcomes. The objective of this project was to address the paucity of evidence from the UK on the risk from air pollution in pregnancy. The research aim was to investigate the effects of ambient air pollution on adverse pregnancy outcomes using retrospective birth outcome data from the ‘North West Perinatal Survey Unit’ (NWPSU) during the period 2004 to 2008.In addition, primarily to determine the most appropriate exposure estimation method, a prospective comparison study (n=85) was performed to compare personal measurements of nitrogen oxides (NOx) and specifically nitrogen dioxide (NO₂) with commonly used exposure estimation techniques. This study informed two further studies which quantified the effects from air pollution in pregnancy using a large retrospective cohort from the NWPSU. The first, investigated the effects of maternal residential proximity to major roads on low birthweight (LBW), small for gestational age (SGA) and preterm birth (PTB). The second, investigated the effects of NOx, NO₂, carbon monoxide (CO) and particulate matter (PM₂.₅ and PM₁₀) based on estimates from a novel spatio-temporal air pollution model and stationary monitor sites on SGA, PTB and mean birth weight change. Linear and logistic regression models were used to quantify the risk of adverse pregnancy outcomes from living in close proximity to a major road and to specific ambient pollutants. Odds ratio (OR) associations and mean birth weight change were calculated for each of the pollutants with exposure averaged over the entire pregnancy and for specific pregnancy periods to establish critical windows of exposure. Models were adjusted for maternal age, ethnicity, parity, socio-economic status, birth season, body mass index and smoking. No statistically significant associations were found between living <200m from a major road and adverse pregnancy outcomes. Based on the spatio-temporal modelled air pollution estimates, an increased risk of SGA was found in later pregnancy with NO₂ (OR=1.14, 95%CI= 1.00-1.30), CO (OR=1.21, 1.02-1.42), PM₂.₅ (OR=1.10, 1.00-1.21) and PM₁₀ (OR=1.12, 1.00-1.25). This study provides additional evidence that women exposed to high air pollution concentrations in pregnancy are at an increased risk of an SGA birth, but not for PTB. However, there was no evidence of an effect on SGA for exposures below the current legal air quality limits.

No description available.

No description available.

No description available.

published_or_final_version / Urban Planning and Environmental Management / Doctoral / Doctor of Philosophy

Yau Yat Man. / Bibliography: leaves 124-129 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

Graduation date: 2005

In view of the worsening air quality in the world, more concerns are focused on the environment. This thesis uses the technique of CFD and develops the computer model to investigate the wind and pollutant transport, as well as the chemistry of reactive pollutants in idealized two-dimensional (2D) street canyons. Three scientific questions are raised in this thesis. The first task is to find out the po- sition with the most favorable pollutant removal along the ground level over 2D idealized street canyon of different building-height-to-street-width (aspect) ratios (ARs). The di- mensionless parameter, C, represents the pollutant removal performance. In the isolated roughness regime, the two local maximum C locate at the reattachment point and the windward corner. In the wake interference regime, C is peaked on the windward side. The number of vertically aligned recirculations depends on the street depth in the skimming flow regime. The sizes of the secondary recirculation upstream and downstream deter- mine how the maximum C shifts from the street centre. After identifying the position of peaked pollutant removal rate at the ground level, the emission source should be placed with the highest constant C in order to remove the pollutants upward more quickly to safeguard the street-level air quality. After understanding the best pollutant removal in the street canyon of different ARs, the second task is to find out what AR is the most favorable for the ventilation and pollutant removal across the roof level. The three parameters, namely friction factor, air exchange rate (ACH) and pollutant exchange rate (PCH), are introduced to quantify the pressure difference to sustain the mean flow, the ventilation and pollutant removal, respectively. The turbulence contributes more than 70% to the total ACH and PCH in all the three flow regimes. By increasing the atmospheric turbulence in building geometry as well as the surface roughness, the ventilation and pollutant removal performance can be improved. The linear relation between the friction factor and ACH demonstrates the larger resistance that in turn promotes the air exchange over the roof level. The physical dispersion is studied; however atmospheric pollutants are seldom in- ert but chemically reactive instead. The last task is to include the three common air pollutants, NO, NO2 and O3, in the simple NOx ?O3 mechanism in terms of the photo- stationary state and reaction rates. The Damkohler numbers of NO and O3, DaNO and DaO3, are parameterized by the concentrations of the sources NO and O3. The normalized mean and fluctuation NO, NO2 and O3 are separately considered. The integrated pho- tostationary state (PSS) in the first canyon increases with DaO3 under the same DaNO. The integrated PSS of the second to the twelveth street canyons are compared with each case, the monotonic increase in the PSS from the second to twelveth canyon is perceived in DaNO/DaO3 1, 0.03, 0.02, 0.001 and 0.000333. Further decreases the DaNO/DaO3 to 0.000143, 0.000125, 0.000118, 0.000111 and 0.0001, the PSS is found to be non-linear and the trough appears in the fourth and fifth canyons. / published_or_final_version / Mechanical Engineering / Master / Master of Philosophy