Daniel Wang

Traffic-Related Air Pollution and Acute Changes in Heart Rate Variability and Respiratory Function in Urban Cyclists

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.

Receptor model based identification of PM2.5 sources in Canadian cities

Abstract Source apportionment of 24–hour integrated PM 2.5 chemical speciation data, collected at five Canadian urban sites, Windsor, Toronto, Montreal, Halifax, and Edmonton was performed using the receptor model, Positive Matrix Factorization (PMF). In order to determine the influences of local and regional sources, in–depth wind direction and back trajectory analyses were performed using the conditional probability function (CPF) and the potential source contribution function (PSCF). The highest PM 2.5 levels were observed in Windsor followed by Toronto and Montreal. Secondary sulfate and nitrate were the major factors contributing to the PM 2.5 mass, accounting for 41% – 61% in the five sites. These secondary factors were associated with trans–boundary emissions from Ohio, Pennsylvania, and New York. An elemental carbon (EC)–rich factor was identified in Windsor, Toronto, and Montreal, characterized by distinct EC and organic carbon (OC) profiles. The EC–rich factor accounted for 6% – 19% of the total PM 2.5 mass in summer and also appeared to be related to trans-boundary pollutants. The combined contributions of traffic and road dust ranged from 14% to 19%, with a portion of the nitrate factor also coming from vehicles. In Halifax, sea salt was the second strongest source, contributing 18% of the PM 2.5 . In Edmonton, strong correlation of volatile organic compounds with the major PM 2.5 factors suggested that local industrial sources were significant sources of secondary aerosol. Further, biomass burning contributed 12% of the PM 2.5 mass in Edmonton. Both local and regional sources were found to contribute at all sites. Thus, PM 2.5 can be reduced at all the sites through local controls. However given the significant contribution of trans–boundary contributions to the PM 2.5 mass, a substantial reduction of PM 2.5 in four of the cities will also require agreements to limit the production and transport of trans–boundary pollutants.

Windsor, Ontario Exposure Assessment Study: Design and Methods Validation of Personal, Indoor, and Outdoor Air Pollution Monitoring

ABSTRACT The Windsor, Ontario Exposure Assessment Study evaluated the contribution of ambient air pollutants to personal and indoor exposures of adults and asthmatic children living in Windsor, Ontario, Canada. In addition, the role of personal, indoor, and outdoor air pollution exposures upon asthmatic childrens respiratory health was assessed. Several active and passive sampling methods were applied, or adapted, for personal, indoor, and outdoor residential monitoring of nitrogen dioxide, volatile organic compounds, particulate matter (PM; PM ≤ 2.5 μm [PM2.5] and ≤ 10 μm [PM10] in aerodynamic diameter),elemental carbon, ultrafine particles, ozone, air exchange rates, allergens in settled dust, and particulate-associated metals. Participants completed five consecutive days of monitoring during the winter and summer of 2005 and 2006. During 2006, in addition to undertaking the air pollution measurements, asthmatic children completed respiratory health measurements (including peak flow meter tests and exhaled breath condensate) and tracked respiratory symptoms in a diary. Extensive quality assurance and quality control steps were implemented, including the collocation of instruments at the National Air Pollution Surveillance site operated by Environment Canada and at the Michigan Department of Environmental Quality site in Allen Park, Detroit, MI. During field sampling, duplicate and blank samples were also completed and these data are reported. In total, 50 adults and 51 asthmatic children were recruited to participate, resulting in 922 participant days of data. When comparing the methods used in the study with standard reference methods, field blanks were low and bias was acceptable, with most methods being within 20% of reference methods. Duplicates were typically within less than 10% of each other, indicating that study results can be used with confidence. This paper covers study design, recruitment, methodology, time activity diary, surveys, and quality assurance and control results for the different methods used. IMPLICATIONS It is important to obtain data to identify any factors that can influence the relationships among personal, indoor, and outdoor concentrations for a range of air pollutants. Ensuring that the methods used are valid and comparable to reference methods used in typical air pollution, monitoring is crucial for data to be of use to regulators. These exposure data can then be used to develop risk management policies that reduce personal and indoor exposures to air pollutants.

Predictors of Indoor Air Concentrations in Smoking and Non-Smoking Residences

Indoor concentrations of air pollutants (benzene, toluene, formaldehyde, acetaldehyde, acrolein, nitrogen dioxide, particulate matter, elemental carbon and ozone) were measured in residences in Regina, Saskatchewan, Canada. Data were collected in 106 homes in winter and 111 homes in summer of 2007, with 71 homes participating in both seasons. In addition, data for relative humidity, temperature, air exchange rates, housing characteristics and occupants’ activities during sampling were collected. Multiple linear regression analysis was used to construct season-specific models for the air pollutants. Where smoking was a major contributor to indoor concentrations, separate models were constructed for all homes and for those homes with no cigarette smoke exposure. The housing characteristics and occupants’ activities investigated in this study explained between 11% and 53% of the variability in indoor air pollutant concentrations, with ventilation, age of home and attached garage being important predictors for many pollutants.

Personal exposure to specific volatile organic compounds and acute changes in lung function and heart rate variability among urban cyclists.

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 2.0 millisecond (ms) (95% CI: 0.65, 3.2) increase in SDNN (standard deviation of normal-to-normal intervals), a 24 ms(2) (95% CI: 6.6, 41) increase in HF (high frequency power), and a 65 ms(2) (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 5.8 ms (95% CI: -9.8, -1.7): decrease in SDNN and a 24 ms(2) (95% CI: -44, -7.9) decrease in HF, respectively. IQR increases in benzene exposure were associated with a 1.7 ppb (95% CI: 1.1, 2.3) increase in exhaled nitric oxide and each IQR increase in 3-methylhexane exposure was associated with a 102 mL (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.

Summertime formaldehyde at a high‐elevation site in Quebec

Measurements of formaldehyde were made during the summer of 1996 at a high-elevation site in Quebec as part of the North American Research Strategy on Tropospheric Ozone-Canada East (NARSTO-CE) measurement program. Gas phase mixing ratios were determined continuously by removing formaldehyde from the air in a glass coil scrubber, and producing a fluorescent dimer through the Hantzsch reaction. Average mixing ratios of formaldehyde were 1.3 and 0.8 ppbv for dry and wet periods, respectively. Highest values of HCHO were observed July 1-2 with a maximum mixing ratio of 4.6 ppbv. Fog water samples were also collected and analyzed for HCHO on five afternoon periods. Comparison of HCHO in the gas and aqueous phases shows reasonable agreement with Henrys law equilibrium. For dry periods July 1-12, relationships were examined between formaldehyde and other chemical species also measured at the site. Data were segregated based on the ratio of NO x to NO y and on the level of anthropogenic hydrocarbons present in the air mass. For the majority of the data, formaldehyde increased with both ozone and products of NO x oxidation (NO z ) and was inversely related to the NO x /NO y ratio. During the high HCHO episode July 1-2, HCHO was correlated with neither ozone nor NO 2 illustrating the different chemistry at the site on these days. A chemical box model was used to examine sources of HCHO July 1-4. The model suggests that biogenic hydrocarbons contribute on average 53% of the locally produced formaldehyde, the remainder resulting from the oxidation of methane (19%), anthropogenic VOCs (16%), acetaldehyde (7%), and organic peroxides (3%). The model cannot account for the July 1-2 formaldehyde mixing ratios from the chemistry measured at the site. This implies that an additional HCHO source not included in the model was responsible for the high levels on those days.

Differences between measured and reported volatile organic compound emissions from oil sands facilities in Alberta, Canada.

Significance Validation of volatile organic compound (VOC) emission reports, especially from large industrial facilities, is rarely attempted. Given uncertainties in emission reports, their evaluation and validation will build confidence in emission inventories. It is shown that a top-down approach can provide measurement-based emission rates for such emission validation. Comparisons with emission reports from Alberta oil sands surface mining facilities revealed significant differences in VOC emissions between top-down emissions rates and reports. Comparison with VOC species emission reports using currently accepted estimation methods indicates that emissions were underestimated in the reports for most species. This exercise shows that improvements in the accuracy and completeness of emissions estimates from complex facilities would enhance their application to assessing the impacts of such emissions. 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.

Biogenic isoprene in the Lower Fraser Valley, British Columbia

Tropospheric ozone is formed by photochemical reactions between nitrogen oxides (NOx) and volatile organic compounds. In some regions, biogenic isoprene may be a significant contributor to the production of tropospheric ozone. The contribution of biogenic isoprene is an important aspect of regional ozone chemistry as it represents an ozone precursor that cannot be eliminated through emissions controls. The purpose of this study was to evaluate the contribution of isoprene to the production of tropospheric ozone in the Lower Fraser Valley, British Columbia. Seasonal trends and diurnal profiles were used to examine isoprenes relationship with temperature, to determine its source, and to investigate the chemical and physical factors that limit the ambient levels of isoprene present in the region. Total isoprene levels in the Lower Fraser Valley were low, and evidence suggested that a substantial fraction originated from anthropogenic rather than biogenic sources. Diurnal isoprene profiles were generally flat, and the times of the highest concentrations did not coincide with peak NOx levels nor with the times of optimal ozone-producing meteorological conditions. These results are consistent with those of previously reported studies and suggest that biogenic isoprene may not be as important to the tropospheric ozone chemistry in the Lower Fraser Valley as it is in some southern U. S. cities.

Comparison of organic compound compositions in the emissions inventory and ambient data for the Lower Fraser Valley

Weimin Jiang (corresponding author) is a research associate at the Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6; phone: (613) 998-3992; e-mail: weimin.jiang@nrc.ca. Don Singleton and Mark Hedley are research officers at the Institute for Chemical Process and Environmental Technology, National Research Council, Canada. Non-methane organic compound (NMOC) composition in an episode-specific emissions inventory is systematically compared with the average summer ambient NMOC composition in the Lower Fraser Valley (LFV) of British Columbia, Canada. The comparison is made on the basis of NMOC classes, carbon numbers of species and classes, and individual chemical species. The composition of species present in the inventory but not measured in the atmosphere is also presented. It is found that the ambient and emissions inventory compositions are in reasonable agreement, with a few exceptions. Because of the similarity in the compositions, the emissions profile in the LFV can be used to approximate the ambient NMOC profile in photochemical modeling of the region. A similar validation procedure would be required in other regions.Discrepancies exist between the emissions inventory and the ambient data for the biogenic compounds isoprene.

Air toxics in Canada measured by the National Air Pollution Surveillance (NAPS) program and their relation to ambient air quality guidelines

ABSTRACT 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.