Search

Unlabelled: This study reports ambient concentrations of 63 air toxics that were measured in Canada by the National Air Pollution Surveillance (NAPS) program over the period 2009-2013. Measured concentrations are compared with ambient air quality guidelines from Canadian jurisdictions, and compounds that exceeded guidelines are identified and discussed. Although this study does not assess risk or cumulative effects, air toxics that approached guidelines are also identified so that their potential contribution to ambient air toxics pollution can be considered. Eleven air toxics exceeded at least one guideline, and an additional 16 approached guidelines during the study period. Four compounds were measured using methods whose detection limits exceeded a guideline value, three of which could not be compared with guidelines, since they were not detected in any samples. The assessment of several metal(loid) concentrations is tentative, since they were measured only in fine particulate matter (PM) but compared with guidelines based on coarse or total PM. Improvements to sampling and analysis techniques for the latter compounds as well as for those whose methods are subject to known uncertainties would improve confidence in reported concentrations and their relation to applicable guidelines. Analysis of sampling strategies for all compounds found to exceed or approach guidelines would contribute to ensuring that their spatiotemporal coverage is adequate. Examination of the air toxics not measured by NAPS but having guidelines in Canadian jurisdictions or being included in other programs such as the U.S. National-Scale Air Toxics Assessment (NATA) would contribute to ensuring that the full suite of pollutants relevant to ambient air quality in Canada is subject to adequate study. The results of this study can be applied to evaluating the effectiveness of toxic substances management in Canada., Implications: Recent measurements of 63 air toxics in Canada by the National Air Pollution Surveillance (NAPS) program showed that 11 compounds exceeded daily or annual ambient air quality guidelines and that an additional 16 compounds approached such guidelines within an order of magnitude. The results of this study can be applied to evaluating the effectiveness of toxic substances management in Canada and to identifying compounds that merit further investigation.

Background: Few studies have examined the acute health effects of air pollution exposures experienced while cycling in traffic., Objectives: We conducted a crossover study to examine the relationship between traffic pollution and acute changes in heart rate variability. We also collected spirometry and exhaled nitric oxide measures., Methods: Forty-two healthy adults cycled for 1 hr on high- and low-traffic routes as well as indoors. Health measures were collected before cycling and 1-4 hr after the start of cycling. Ultrafine particles (UFPs; ≤ 0.1 μm in aerodynamic diameter), particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5), black carbon, and volatile organic compounds were measured along each cycling route, and ambient nitrogen dioxide (NO2) and ozone (O3) levels were recorded from a fixed-site monitor. Mixed-effects models were used to estimate associations between air pollutants and changes in health outcome measures relative to precycling baseline values., Results: An interquartile range increase in UFP levels (18,200/cm3) was associated with a significant decrease in high-frequency power 4 hr after the start of cycling [β = -224 msec2; 95% confidence interval (CI), -386 to -63 msec2]. Ambient NO2 levels were inversely associated with the standard deviation of normal-to-normal (NN) intervals (β = -10 msec; 95% CI, -20 to -0.34 msec) and positively associated with the ratio of low-frequency to high-frequency power (β = 1.4; 95% CI, 0.35 to 2.5) 2 hr after the start of cycling. We also observed significant inverse associations between ambient O3 levels and the root mean square of successive differences in adjacent NN intervals 3 hr after the start of cycling., Conclusions: Short-term exposures to traffic pollution may contribute to altered autonomic modulation of the heart in the hours immediately after cycling.

Large-scale oil production from oil sands deposits in Alberta, Canada has raised concerns about environmental impacts, such as the magnitude of air pollution emissions. This paper reports compound emission rates (E) for 69–89 nonbiogenic volatile organic compounds (VOCs) for each of four surface mining facilities, determined with a top-down approach using aircraft measurements in the summer of 2013. The aggregate emission rate (aE) of the nonbiogenic VOCs ranged from 50 ± 14 to 70 ± 22 t/d depending on the facility. In comparison, equivalent VOC emission rates reported to the Canadian National Pollutant Release Inventory (NPRI) using accepted estimation methods were lower than the aE values by factors of 2.0 ± 0.6, 3.1 ± 1.1, 4.5 ± 1.5, and 4.1 ± 1.6 for the four facilities, indicating underestimation in the reported VOC emissions. For 11 of the combined 93 VOC species reported by all four facilities, the reported emission rate and E were similar; but for the other 82 species, the reported emission rate was lower than E. The median ratio of E to that reported for all species by a facility ranged from 4.5 to 375 depending on the facility. Moreover, between 9 and 53 VOCs, for which there are existing reporting requirements to the NPRI, were not included in the facility emission reports. The comparisons between the emission reports and measurement-based emission rates indicate that improvements to VOC emission estimation methods would enhance the accuracy and completeness of emission estimates and their applicability to environmental impact assessments of oil sands developments. [ABSTRACT FROM AUTHOR]

Abstract: Ground level ozone represents a significant air quality concern in Toronto, Canada, where the national 65 ppb 8-h standard is repeatedly exceeded during the summer. Here we present an analysis of nitrogen dioxide (NO2), ozone (O3), and volatile organic compound (VOC) data from federal and provincial governmental monitoring sites from 2000 to 2007. We show that summertime VOC reactivity and ambient concentrations of NO2 have decreased over this period of time by up to 40% across Toronto and the surrounding region. This has not resulted in significant summertime ozone reductions, and in some urban areas, it appears to be increasing. We discuss the competing effects of decreased ozone titration leading to an increase in O3, and decreased local ozone production, both caused by significant decreases in NO x concentrations. In addition, by using local meteorological data, we show that annual variability in summer ozone correlates strongly with maximum daily temperatures, and we explore the effect of atmospheric transport from the southwest which has a significant influence on early morning levels before local production begins. A mathematical model of instantaneous ozone production is presented which suggests that, given the observed decreases in NO x and VOC reactivity, we would not expect a significant change in local ozone production under photochemically relevant conditions. These results are discussed in the context of Toronto''s recent commitment to cutting local smog-causing pollutants by 20% by 2012. [Copyright &y& Elsevier]

Abstract: Background: Few studies have examined the acute cardiorespiratory effects of specific volatile organic compound (VOC) exposures from traffic pollution. Methods: A cross-over study was conducted among 42 healthy adults during summer 2010 in Ottawa, Canada. Participants cycled for 1-h along high and low-traffic routes and VOC exposures were determined along each route. Lung function, exhaled nitric oxide, and heart rate variability were monitored before cycling and 1–4h after the start of cycling. Bayesian hierarchical models were used to examine the relationship between 26 VOCs and acute changes in clinical outcomes adjusted for potential confounding factors. Results: Each inter-quartile range (IQR) increase in propane/butane exposure was associated with a 2.0millisecond (ms) (95% CI: 0.65, 3.2) increase in SDNN (standard deviation of normal-to-normal intervals), a 24ms2 (95% CI: 6.6, 41) increase in HF (high frequency power), and a 65ms2 (95% CI: 11, 118) increase in LF (low frequency power) in the hours following cycling. IQR increases in ethane and isoprene were associated with a 5.8ms (95% CI: −9.8, −1.7): decrease in SDNN and a 24ms2 (95% CI: −44, −7.9) decrease in HF, respectively. IQR increases in benzene exposure were associated with a 1.7ppb (95% CI: 1.1, 2.3) increase in exhaled nitric oxide and each IQR increase in 3-methylhexane exposure was associated with a 102mL (95% CI: −157, −47) decrease in forced expiratory volume in 1-s. Conclusions: Exposure to traffic-related VOCs may contribute to acute changes in lung function, inflammation, or heart rate variability. [Copyright &y& Elsevier]