Air

Residential Indoor and Outdoor Coarse Particles and Associated Endotoxin Exposures

Inhalation of course particles, between 2.5 and 10 micrometers in diameter, in air are known to affect respiratory functions of Canadians. Health Canada is working to understand the major sources of exposure to pollutants in indoor and outdoor air. Sources of outdoor coarse particles include windblown dust or sea salt and combustion-related particles, and may also include biological contaminants such as pollen, fungi, and endotoxins. Endotoxins are present within certain types of bacteria and cause an inflammatory response by the body following exposure. This study, published in Atmospheric Environment in collaboration with the Regina Qu’Appelle Health Region, measured residential indoor and outdoor coarse particle concentrations, and associated endotoxin levels, in Regina in 2007. Coarse particle concentrations were found to be higher indoors than outdoors in winter, and higher outdoors in the summer, whereas endotoxin levels were consistently higher outdoors. Significant variability was found between the coarse particle concentrations measured within homes compared with measurements made at centralized monitoring sites within the community. These results will help to refine epidemiology studies which generally use measurements from centralized monitoring sites as a substitute for personal exposure measurements.   For more information, please consult Atmospheric Environment, Volume 45, Issue 39, December 2011, 7064–7071.

Urinary Polycyclic Aromatic Hydrocarbons as a Biomarker of Exposure to PAHS in Air: A Pilot Study among Pregnant Women

Exposure to polycyclic aromatic hydrocarbons (PAHs), formed through incomplete combustion and found in the emissions expelled by vehicles, industry, fireplaces, barbeques, candle burning, tobacco smoke, etc., have been linked to adverse health and pregnancy outcomes. Health Canada is working to better understand sources of PAH exposure. In particular, this study followed a group of 19 pregnant women, a segment of the population that may be more vulnerable to the health effects of air pollution. Participants were living in homes where air pollution levels were classed as either “high” (urban/close to industry) or “low” (sub-urban) in Hamilton, Ontario. PAH concentrations were measured in personal, indoor and outdoor air and through the analyses of markers of PAHs in the participants’ urine. Results indicate that exposure to heavy molecular weight PAHs is related to outdoor sources of PAHs (e.g. vehicles, industry), while lighter molecular weight PAHs were related to indoor sources (e.g. candle burning) and exposure to tobacco smoke. Living in “high” pollution areas of Hamilton resulted in higher personal exposure to PAHs compared to living in the “low” air pollution areas. The results suggest that centralized air pollution monitoring sites may be useful in estimating exposure to heavy molecular weight PAHs, but they may not adequately predict personal exposure to lighter molecular weight PAHs. As the first study on PAHs to measure these chemicals in pregnant women, the knowledge gained from this study can be used in future work to more accurately predict PAH exposure and the associated population health effects. Results of the research are published in the Journal of Exposure Science and Environmental Epidemiology, 2012 Jan-Feb;22(1):70-81.

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

Health Canada is working to understand the short-term health effects of air pollution in a variety of situations, including those related to cycling in high traffic areas. During the summer of 2010, Health Canada conducted a study in Ottawa, Ontario to examine the impact of air pollution exposure on short-term changes in lung and heart function among healthy cyclists. Forty-two healthy adults (19 to 58 years of age) cycled for 1 hour on high- and low-traffic routes, as well as indoors. Traffic-related air pollutants were measured along each cycling route and health measures, including lung function and heart rate variability, were collected before and after cycling. Air pollution exposures were significantly increased when cycling on the high-traffic route compared to the low-traffic route. While air pollution exposures did not have a significant impact on lung function in healthy cyclists, nitrogen dioxide, ozone, and ultrafine particle levels (very small particles, less than 100 nanometres, produced by vehicle emissions) appeared to have an important impact on the biological systems that regulate heart rate. The results of this study suggest that exposure to traffic-related air pollution may result in short-term changes to the biological systems that regulate the heart. This research may inform the advice Health Canada provides to Canadians to reduce their risks from the effects of air pollution. Results of the research are published in Environmental Health Perspectives, 2011 Oct: 119(10): 1373-8.

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

Air pollutants from both indoor and outdoor sources may result in adverse impacts on the health of Canadians.  The activities that Canadians choose to engage in, and the indoor and outdoor air pollutant concentrations, impact personal exposure levels to air pollution.  Health Canada, in partnership with the University of Windsor, undertook a study in Windsor, Ontario to investigate personal levels of air pollution exposure.  This study investigated the contribution of air pollution from indoor and outdoor sources on the personal exposure of both adults and asthmatic children, and assessed the impacts of air pollution exposure on the respiratory health of the children included in the study.  In total, 50 adults and 51 asthmatic children participated in the study, which took place over 5 consecutive days in both the summer and winter.  Indoor, outdoor and personal monitoring was conducted for a number of pollutants.  The asthmatic children’s respiratory health was assessed, and each child kept a diary of their respiratory symptoms over the study period.  Analyses of the relationships between air pollution monitoring, respiratory health and personal exposure data collected from this study are underway. Results from this study will improve our understanding of the relative health impacts of indoor and outdoor sources of air pollution and inform the development of actions to reduce the health risks Canadians can experience from air pollution.  Results of this research, study design and methods are published in the Journal of the Air and Waste Management Association (March 2011), 61(3):324-338.

Back-Extrapolation of Estimates of Exposure from Current Land-Use Regression Models

Air pollution concentrations can be affected by a number of factors, including geographic locale, limiting the applicability of centralized monitoring site data to estimate personal exposure.  Health Canada is working to understand these differences and improve the prediction of air pollution exposures within different urban areas.  In this study, Health Canada, in collaboration with McGill University, applied land-use regression modelling, which uses pollutant monitoring data along with land-use information such as traffic volume, distance to industrial sources, distance to ports and harbours, and housing and population density, to better predict air pollution exposure throughout an urban area.  Health Canada investigated three new methods that used land-use regression models to predict past air pollution exposure.  To start, nitrogen dioxide (NO₂) levels in Montreal were measured at 130 locations over three two-week periods in 2005 and 2006.  This information, along with fixed site monitoring data, land-use and traffic data were used to develop a current land-use regression model for Montreal.  Next, historic data on land-use and traffic were used to develop models for time periods that were 10 and 20 years in the past using three different techniques.  These models were used to estimate air pollution exposure for subjects involved in a 1996 study of postmenopausal breast cancer.  The analyses from the 2006 and the three historic models demonstrated similar levels of elevated risk of postmenopausal breast cancer associated with increased exposure to nitrogen dioxide.  As this research is some of the first to investigate the use of land-use regression modelling to back-predict air pollution exposure, further analyses will be required to evaluate the accuracy of the different techniques.  Land-use regression modelling is a valuable tool to estimate air pollution exposure and, it can be used to predict historic exposure levels.  This work is important to improving understanding of the impacts of long-term exposure to air pollution on the health of Canadians.  Results of this research are published in Atmospheric Environment (November 2010), 44(35): 4346-4354

Evaluation of Land-Use Regression Models Used to Predict Air Quality Concentrations in an Urban Area

Estimating exposure to air pollution within Canadian cities is important to understanding the long-term impacts of air pollution on the health of Canadians.  However, air pollution levels within a city can vary greatly depending on geographic location.  This Health Canada project, undertaken in collaboration with the U.S. Environmental Protection Agency, evaluated the ability of land-use regression models to predict air quality concentrations across an urban environment.  Land-use regression modelling uses pollutant monitoring data along with land-use information, such as traffic volume, distance to industrial sources, distance to ports and harbours, as well as housing and population density, to better predict air pollution exposure throughout an urban area. In this work, regional air quality models were used to predict air pollutant levels in New Haven, Connecticut.  Subsets of the modelled air quality data (from between 25 and 285 specific locations), along with land-use data, were used to develop land-use regression models for the city.  A comparison between the land-use regression model’s performance at independent test locations indicated that as the number of locations used to develop the  regression model increased, the accuracy increased.  Results suggest that air quality modelling results could be used to inform the development of land-use regression models and improve their performance.  This work supports Health Canada’s ability to better predict air pollutant exposure through the development of more accurate land-use regression models.  Results of this research are published in Atmospheric Environment (September 2010), 44(30): 3660-3668.

Buoyancy-Corrected Gravimetric Analysis of Lightly Loaded Filters

Particulate matter in the air may result in adverse impacts on the respiratory health of Canadians. Accurate measurements of particulate matter help Health Canada to evaluate the potential for adverse health effects caused by exposure to environmental releases of particulate matter, e.g. from industrial and automobile emissions. In this study, Health Canada used its patented Archimedes M3^TM weighing facility (see US Patent 7357045) to develop a method to more accurately measure particulate matter and better understand how environmental factors contribute to measurement errors. For example, when very small samples (<100 micrograms) of particulate matter are being weighed, measurement errors associated with changes in environmental conditions (i.e. temperature, relative humidity, and air density) are more significant. The results of this research, published in the Journal of the Air & Waste Management Association, have enabled Health Canada to develop a method to overcome these challenges. Future research will be directed towards development of guidelines for gravimetric analysis of nanoparticles and other low mass samples of airborne particulate matter such as personal and indoor exposure samples. Ultimately, this research will strengthen Health Canada’s ability to perform toxicological risk assessments.  For more information, please consult the Journal of the Air & Waste Management Association, 2010 Sep; 60(9):1065-77.

Concentration Distribution and Bioaccessibility of Trace Elements in Nano and Fine Urban Airborne Particulate Matter: Influence of Particle Size

Particulate matter in the air may result in adverse impacts on the respiratory health of Canadians. Health Canada is working to understand the major sources of exposure to particulate matter and which components of particulate matter are of greatest health risk. In this study, Health Canada used highly sensitive measurement technologies to evaluate particulate matter in Ottawa’s urban air. Researchers separated the components of the particulate matter using a device which categorizes particulate matter according to size. From smallest to largest, the categories included: nanoparticles (less than 100 nanometres, also called “ultrafine particles”); fine particles (100 nanometres to 1 micrometre); and coarse particles (1 to 10 micrometres). The mass and components of the particulate matter were determined using an extremely sensitive weighing facility (Archimedes M3^TM, see  US Patent 7357045) and mass spectrometry analysis, respectively. Health Canada found that the elements vanadium (V), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), selenium (Se) and cadmium (Cd) tended to be more concentrated in the nanoparticle-size fraction. Other elements, including iron (Fe), strontium (Sr), molybdenum (Mo), tin (Sn), antimony (Sb), barium (Ba) and lead (Pb), were more concentrated in the fine-particle fraction. Results suggested that motorized vehicles were a major contributor to the composition of these urban particulate matter samples. Application of these technologies will be useful to inform motor vehicle emission level and fuel additive guidelines. Results of this research are published in the Journal of Water, Air and Soil Pollution, Volume 213, Numbers 1-4, 211-225.

Hepatic mRNA, microRNA, and miR-34a-Target Responses in Mice after 28 Exposure to Doses of Benzo(a)pyrene that Elicit DNA Damage and Mutation

As part of the Chemicals Management Plan, Health Canada conducts research on chemicals in support of its mandate to assess the risks of various substances to Canadians. Benzo(a)pyrene (BaP) is an environmental toxin that has been shown to cause cancer and DNA mutation in laboratory animals. As a result of the extensive published information available on the effects of BaP, it also serves as an excellent model for the development of new methodologies to study toxicity because one can compare existing and new methods directly. Toxicogenomics is a relatively new discipline that investigates the effects of exposure to chemicals on all of the genes within an organism, by examining what genes are turned on and off by the chemical.

In an effort to better understand the toxicology of BaP and to explore the potential application of toxicogenomics to the risk assessment of BaP, groups of male mice were treated with varying concentrations of BaP for 28 days. BaP exposure resulted in 134 genes (of 40,000) that were statistically significantly altered in the liver. These genes were primarily involved in the metabolism of BaP, the response to DNA damage, and how cells divide and replicate. This finding is consistent with previous research investigations. The results of the study provide important information on the genes and mechanisms involved in the response of the liver to BaP exposure across a range of doses. The gene changes measured are highly aligned with observed molecular changes, supporting the use of toxicogenomics as a tool to predict toxicity. These results will also be used to help determine how toxicogenomics data can best support risk assessments at Health Canada. Results of this study were published in the Environ Mol Mutagen. 2012 Jan;53(1):10-21.

Spatial Distribution of Polycyclic Aromatic Hydrocarbons (Pahs) in an Urban Environment

Exposure to polycyclic aromatic hydrocarbons (PAHs), formed through incomplete combustion and found in the emissions expelled by vehicles, industry, fireplaces, barbeques, candle burning, tobacco smoke, etc., has been linked to health effects including adverse pregnancy outcomes.  Estimating exposure to PAHs within Canadian cities is important to understanding the long-term impacts of these compounds on the health of Canadians.  However, air pollution levels within a city can vary greatly depending on geographic location.  Health Canada, in collaboration with Carleton University, undertook this study in Hamilton, Ontario, to better understand the spatial distribution of PAHs and fine particulate matter, another air pollutant linked to health impacts, by measuring outdoor air concentrations.  Air pollution levels were measured in two seasons, winter and summer of 2009 at approximately 50 locations across the city of Hamilton.  This study found that outdoor fine particulate matter and PAH concentrations were greater below the Niagara escarpment, which runs through the city and bisects it into lower and upper regions.  The difference in PAH concentrations between the area below the escarpment and that above it was  much greater than for fine particulate matter in both summer and winter. Elevated levels of both pollutants were observed to occur near or downwind of the central business district and industrialized harbourfront area, suggesting the contribution of local sources.  The PAH levels also exhibited a greater degree of variability than the fine particulate matter both above and below the escarpment.  This study is one of the first to measure PAHs on such a local scale across a city in two seasons.  The knowledge gained from this study can be used in future work to more accurately predict PAH exposure and the associated population health effects. Results of this research are published in Atmospheric Environmental 59 (2012) 272-283 (on-line May 2012).

Note this is available in final form on-line which will be the November 2012 issue.

Germline Mutation Rates in Mice Following in Utero Exposure to Diesel Exhaust Particles by Maternal Inhalation

Particulate air pollution is widespread in many urban environments and Health Canada is responsible for working to ensure that accurate information on the health risks from pollution is available to all Canadians, and acting to reduce these health risks as much as possible.  One source of particulate air pollution is diesel exhaust particles (DEPs) from engines.  In order to better understand the impacts of exposure to particulate air pollution on human health during development, Health Canada conducted this study to investigate mutations in the germ cells (sperm and eggs) of mice that were exposed to DEPs while they were in their mother’s uterus (in utero).  Mutations in the DNA of germ cells are particularly important to understand because they can be passed on to offspring and can result in harmful effects, such as heritable diseases, developmental effects and cancers. Pregnant mothers were exposed to DEPs suspended in air.  Their offspring were born, raised to maturity, and then mated with unexposed animals to produce litters of their own.  A 2-fold increase in the mutation rate was found in the mice whose fathers had been exposed in utero.  These results support previous findings that DEPs cause mutations in reproductive cells.  There was also an increase in the number of mutations in the DNA contributed by mothers who were never exposed, when producing offspring with an exposed male.  This result suggests that mutations in the sperm of the exposed male can also cause indirect effects on the DNA coming from the egg of an unexposed female at the time of conception.  Overall, these results demonstrate that exposing mice to inhaled DEPs during their development in utero produced mutations in germ cells that could subsequently be transmitted to their offspring and this knowledge may help Health Canada protect the health of vulnerable populations.  This study was conducted in collaboration with the Danish National Research Centre for the Working Environment and was published in Mutation Research (2011 Jul 1), 712(1-2):55-58.

Physical-Chemical and Microbiological Characterization, and Mutagenic Activity of Airborne Pm Sampled in A Biomass-Fueled Electrical Production Facility

Many areas of the world, including parts of Canada, employ the combustion of biomass (e.g., wood, agricultural waste, animal waste, etc.) to produce heat and electric power.  Transportation, handling and combustion of plant biomass (e.g., straw, wood chips) can result in the generation of airborne particulate material (PM) and occupational exposure to airborne particles, which may contribute to adverse health effects that are important for Health Canada to understand.  To better understand the potential health effects resulting from the combustion of biomass for heat and electricity, Health Canada conducted this study to examine airborne PM at a biomass-fuelled electric power generation facility in Denmark.  The PM was analysed for chemical contaminants such as toxic metals and polycyclic aromatic hydrocarbons (PAHs), as well as its ability to generate reactive oxygen species (ROS) in a liquid suspension and induce genetic mutations in a bacteria test system.  The results showed that PM derived from combusted biomass collected from the boiler room and the biomass storage hall had higher levels of chemical contamination, a higher potential to induce the formation of ROS, and a greater ability to induce genetic mutations in bacteria.  Additional analyses investigated the properties of dust particles generated by agitating the biomass fuel (i.e., straw or wood chips).  The results showed low levels of contamination, and a relatively low potential to induce adverse health effects.  Nevertheless, microbiological analyses did show high concentrations of fungi and bacterial endotoxins (i.e., toxins generated by bacteria) in the dust generated by biomass agitation.  The results indicate that exposure to the PM present in the boiler room and biomass storage area may contribute to an elevated risk of adverse health effects which may be useful to inform regulatory approaches.  This study took place in collaboration with the Danish National Research Centre for the Working Environment and the Geological Survey of Denmark and Greenland and was published in  Environmental and Molecular Mutagenesis (2011 May), 52(4):319-330.