By Ariel Root

Air pollution, green space, and wind turbines. Cardiovascular disease, diabetes, dementia, and cancer. Formal training in statistics, and epidemiology. And partnerships across mathematics, chemistry, geography, and biological disciplines. Paul Villeneuve reflects back on an inspirational co-op work term at Health Canada during his statistics undergraduate training. He was required to apply statistics to better understand specific health issues, but found it much more appealing than theoretical statistics. ā€œI guess,ā€ he laughs, ā€œthatā€™s when I thought epidemiology would be more fun.ā€

Villeneuve is an Associate Professor in the Department of Health Sciences, and cross-appointed to the School of Mathematics and Statistics at ŠÓ°ÉŌ­““ University. He is also an Affiliate Scientist at the Ontario Occupational Cancer Research Centre (OCRC) in Toronto, Senior Editor for the Canadian Journal of Public Health, and an Associate Editor forĀ Health Promotion and Chronic Disease Prevention in Canada.

From the beginning of his time at the Laboratory Centre for Disease Control at Health Canada in 1988, Villeneuve has been involved in controversial health issues that are interwoven with political implications, such as the taxation of cigarettes. Being part of such a strong team of epidemiologists, Villeneuve recalls their high caliber research on topics including physical activity, pesticide use, exposure to radon, and cigarette smoking, including second hand exposure. ā€œIt generated a lot of attention [because] we didnā€™t understand the risks like we do now. These things were extremely relevant to many developing policies; it was easy to become excited about the research.ā€

Today, Villeneuveā€™s primary research interests assess the link between environmental and occupational exposures on the health of Canadians. His combined expertise in epidemiology and biostatistics have resulted in close collaborations with Health Canada, the Public Health Agency of Canada, the OCRC, Cancer Care Ontario, and academic researchers across disciplines in both Canada and the US.

ā€œMuch of my work [focuses] on the health impacts from long-term exposure to air pollution, and the health benefits of green space in urban areas.ā€ His expertise has been applied to several large-scale cohort studies examining the association between ambient air pollution and green space, and chronic diseases. Specifically, associations between outdoor air pollution and the risk of cardiovascular disease, hypertension and diabetes; air pollution and its role on oxidative stress mechanisms related to dementia and neurodegenerative disease; urban green space access and its association with obesity and physical activity; the built environment and development of chronic disease; wind turbines and the potential health impacts and implications; and occupational causes of cancer.

Villeneuveā€™s research is influenced by stakeholder concerns, and the emerging literature. His health research continues to strengthen his belief that multi-disciplinary research teams are critical in developing in-depth health research perspectives and skills. ā€œThink of all the many projects that involve clinicians, statisticians, geographersā€¦ you always need to draw from different disciplines. The nice thing is that people bring different perspectives, and you can then adapt [your research] as you learn from others. Iā€™ve been able to work with many different researchers over long periods of time, and feel lucky to have developed both professional and personal relationships with themā€. At ŠÓ°ÉŌ­““, both the Department of Health Science and The CHAIM Centre combine disciplines, providing opportunities for continuing his engagement in existing and emerging collaborations with various health researchers.

Community engagement and involvement has heavily inspired his research passions. Villeneuve recalls his twenty-year involvement in evaluating the relationship between occupational exposure to radon and lung cancer among Newfoundland fluorspar miners. ā€œWe went into communities, talked with and engaged people, including the miners, and did the analysis.ā€ Villeneuve recalls this as one the first projects that he felt truly excited about his work, ā€œbecause for the first time, it was more than just looking at data. It was [about] going out and talking to people, and hearing of their stories.ā€ A cemetery across the street from the museum of the Newfoundland Fluorspar miners contained many of the individuals who were included in the research. Ā ā€œMy visit there taught me that there are important stories behind the lines of data that I typically run across in an office in Ottawa. Hearing first hand of some of these struggles, and the interest in re-opening the mine because of potential impacts of its closure provided me with a different perspective on how my research could matter at a local level.ā€

In fact, Villeneuve identifies this as one of the most satisfying results of his research; ā€œinteracting with communities, actual residents.ā€ Publications as academic acknowledgement and recognition are satisfying, but ā€œexplaining the researchā€” what it means, getting [community] feedbackā€¦ that level of engagementā€ is more rewarding for Villeneuve. The general public ā€œdoesnā€™t usually read our papers, so town-hall meetings or workshops that bring together more senior community members is importantā€.

Villeneuve notes that online articles have become a very important and widely used method of knowledge translation ā€œthat wasnā€™t there 10 to 15 years agoā€. Ā He also acknowledges the evolution of the epidemiology field, especially in air pollution research. Satellites can now estimate ground level concentrations of pollution, and GPS and other apps provide better estimated exposures at an individual-level. As ā€œthe field continues to evolve, we continue to do things better and better, and [it continues to be] something that appeals to meā€; an appeal that he doesnā€™t see fading out anytime soon.

Here for contact information for Paul Villeneuve

Ever paid attention to the black smoke rising out of the stack pipe of a transport truck? Caught that unmistakable hydrocarbon smell that goes along with it? Transportation of people and their goods is a major culprit for deteriorating the quality of our air. And it doesnā€™t stop there. A long list of other activities, such as heating our homes, electricity generation at power plants, agriculture, and construction of buildings and roads, contributes to ambient air pollution. Because of the wide range of activities responsible and the complex pathways between what is emitted and what we are exposed to, air pollution is a major challenge for environmental managers.

Why all the fuss over air pollution? Well, for a long time, the fields of toxicology and epidemiology have provided evidence that our health is negatively affected by air pollution. Exposure to ambient particulate matter (PM) and ozone carries risks of premature death and illness, both in the short and long-term. In Canada, evidence also exists that NO₂ is an important risk factor for death. Collectively, data from these fields are used to support environmental policies to protect public health. Policies have been developed that limit the levels of pollution in ambient air, such as the Canadian Ambient Air Quality Standards (CAAQS) for PM and ozone set by Environment Canada. Other policies that directly limit emissions at their source have also been set, such as vehicle emission standards that limit tailpipe emissions in Canada.

Imagine a world where we donā€™t need vehicle emission standards because cars donā€™t have tailpipes. Imagine a world where energy is renewable and non-polluting. Imagine a cleaner environment. It seems nearly impossible to achieve, right? Well, it may not be as far away as we think. Emissions of pollutants in North America have been on the decline over the past few decades thanks to stricter environmental policies. Take, for example, NO_x emissions [nitrogen oxide (NO) + nitrogen dioxide (NO₂)] produced in combustion of fuels, such as from power plants or motor vehicles. NO_x undergoes changes in the atmosphere before affecting the air we breathe and has the potential to form PM. NO_x is also a major contributor to NO₂ and ozone (O₃) in the air we breathe ā€“ both powerful oxidants in the human body. Since 1990, according to Environment Canada, Canadaā€™s NO_x emissions have declined roughly 28% as a result of policies to clean exhaust from vehicles and power plants. The result has been a steady decline in ozone and NO₂ and an overall improvement in air quality.

Clearly, if exposure to air pollution affects our health, then as policies become stricter, the health of Canadians benefits. But just how much does society benefit? And how far should policies go before they are sufficient?
Last year, our research team at ŠÓ°ÉŌ­““ University sought to answer these questions. Our findings challenged a fundamental and long-held view in environmental economics ā€“ the law of diminishing returns. According to this law, we should strive only to reduce our emissions by so much, because the benefit of further efforts to reduce emissions diminishes the more and more we reduce. At some point, our efforts to achieve better air quality no longer make sense financially: it costs more to clean the air than it benefits society. But in a study published in 2015, we instead found quite the opposite: the cleaner the air gets, the larger the benefit of reducing our emissions a little bit more. In other words, the less and less we emit, the more effective the next ton of emission control is at reducing ozone pollution. For more, see the blog on

So why do our findings differ from the conventional view? Atmospheric chemistry dictates compounding benefits for pollutants like ozone that are formed through chemical reactions rather than being emitted directly. It tells us how things move and transform in the atmosphere up to the point where we are exposed. But there is another part to this story. How does the human body respond to pollution it is exposed to? Does the bodyā€™s response argue for compounding benefits or diminishing returns?

Characterizing the dose-response curve between pollutants like PM or NO₂ and mortality gives us insight into these questions. Epidemiologists have believed for a long time that the dose-response relationship between exposure and mortality is linear. In other words, in an already pristine environment, making the air a little bit cleaner yields the same reduction in risk as if we cleaned a dirty environment by the same amount. We would get the same benefits to health regardless of how clean the air is initially, as long as we clean it by a comparable amount. But with large cohorts tracking millions of people and their health status over time, epidemiologists now have the power to better delineate the true dose-response relationship. And more and more, studies are finding that the assumed linear relationship may just not be the case. Studies in Canada, such as the Canadian Census, Environment, and Health Cohort (CanCHEC) study have instead found non-linear dose-response relationships for the pollutants NO₂ and PM and mortality. This alternative form of dose-response curve implies that people become more sensitive to pollution as the air becomes cleaner. Or alternatively, if we continue cleaning the atmosphere by progressively reducing our emissions, we get larger and larger reductions in health risks for each small improvement in air quality. The next unit of improved air quality yields more benefit than the previous unit. Sound familiar?

In a newer research project, we worked collaboratively with experts at Health Canada to examine the policy implications of this newer, non-linear form of dose-response relationship. We linked data from CanCHEC with engineered models that track the movement and transformation of air pollutants in the atmosphere from the time they are emitted. The result? A comprehensive set of information that gives insight into how the health of Canadians is directly affected by pollution emitted at its source, whether from the tailpipe of a car or the stack of a power plant.

Our findings indicate that reducing emissions of NO_x brings health benefits of up to $1,400,000 per ton of emission. Where does this benefit come from? When we reduce NO_x, NO₂ in ambient air immediately decreases, and NO₂ is linked to death. But this is just part of the story. With the new, non-linear dose-response model found in CanCHEC, the benefits of reducing emissions increase dramatically as policies become more stringent. With Canada-wide reductions in emissions from all sources, the benefits of reducing each additional ton of emission can grow by 3 or more times. And the benefits are, more often than not, larger than what we would have predicted based on the traditional, linear dose-response curve.

In light of these increasing benefits, we might wonder how much it actually costs to reduce emissions. We have to change our technologies, and even our behaviours, to bring about these changes. So what is the price tag? Well, the answer may not be straightforward. Such costs vary with the type of source (such as vehicles and power plants), and even more so from one place to another. But, on average, the cost of reducing 1 ton of NO_x from industrial stacks can be anywhere from a few hundred dollars to a few thousand. And the costs of reducing the next ton will rise nonlinearly with stricter and stricter policies.

So, is it worth paying? Even without precise estimates of these costs, benefits clearly outweigh the costs by at least an order of magnitude. And even if costs rise as we move towards a cleaner environment, so do the benefits. Itā€™s a race between benefits and costs and the point at which one catches the other may be much farther away than we thought previously.

The intersection of atmospheric science, epidemiology, and economics is a rapidly advancing niche of research. And one thing is clear: whether you approach this problem from an atmospheric science angle or an epidemiology one, we are finding that we ought to be doing more to emit less. Our policies ought to be stricter. We ought to take better control of our environment and our health.

Key references:

Pappin AJ, Mesbah SM, Hakami A, Schott S. 2015. Diminishing returns or compounding benefits of air pollution control? The case of NO_x and ozone. Environ Sci Technol. 49(16):9548-9556.

Pappin AJ, Hakami A, Blagden P, Nasari M, Szyszkowicz M, Burnett RT. The impact of a nonlinear concentration-response function in estimating the benefits of emissions abatement. Environ Res Lett. Under review.

By Anna Tomczak, Department of Health Sciences, ŠÓ°ÉŌ­““ University

For many years the environment has been considered to have important effects on human well-being. Feng shui, for instance, is a Chinese philosophical system that aims to harmonize everyone with the surrounding environment through orientation of buildings and other structures. You might have heard not to align your bed with your door because doors generally have a strong flow of energy that may disrupt sleep. Although the health benefits of orienting your bed in a certain way are debatable, research has found that the surrounding environment does have an effect on both physical and mental health.

Our Aging Brains

As we age, so does our brain. This can lead to a series of irreversible changes that disrupts memory and other cognitive functions. These types of symptoms, when severe enough, are often grouped under the term dementia and include several different diseases, such as disease, , and disease (Butler & Radhakrishnan, 2012). Although dementia is considered an illness of aging, it not only has a major impact on those who have it, but also on their families and on the Canadian health care system. In Canada, it is estimated that there will be over 1,000,000 prevalent cases of dementia by 2038, with a total economic burden of $152.6 billion (Dudgeon, 2010)! The scary part is that there is no known cause of dementia. Several risk factors have been identified as contributors to the disease; however, they only account for part of it. For example, genes play a role in some cases but are thought to be linked to about 5-10% of dementia diagnoses (Dudgeon, 2010). Interestingly, even if an individual is genetically predisposed to a specific form of dementia, some believe that an environmental factor is necessary for the disease to develop (Elbaz, Dufouil & AlpĆ©rovitch, 2007). Additionally, there is no cure for dementia ā€“ it entails damage to the brain that can be slowed down but cannot be reversed. Available drugs may help with some of the related behavioural changes of dementia, but they cannot reverse the damage. With so little known about the causes of dementia, researchers have turned to the environmentā€”both physical and socialā€”in hopes of finding preventative measures.

The Environmentā€”Built and Unbuilt

The environment is a broad term for everything natural and human-built that surrounds us ā€“ so studying its effects on human health can be difficult. As a result, some researchers focus specifically on the built environment, which is defined as buildings, transportation systems, energy systems, open space, and agricultural lands that make up and support our communities (Toronto Public Health, 2015). However, this definition remains quite general and encompasses many different possibilities. Research on the built environment has focused on air quality, available green space, walkability of certain areas, occupational environments, and even on the design of buildings. One can start to see how these types of environments can affect us physically, whether it is through the development of cardiovascular diseases, obesity, or cancer. However, it may be a bit more difficult to make the connections between these types of built environments and cognitive health outcomes, such as dementia. But in fact, there is evidence that our surrounding environment can influence the development and the progression of such diseases. For example, the built environment also encompasses factors that better allow individuals to interact with one another. Increased social interactions have been shown to reduce the risk of developing dementia, and lessen the symptoms of those who have it.

An Interdisciplinary Approach: ŠÓ°ÉŌ­““ā€™s CIHR Meeting

In order to get a better understanding of the relationship between dementia and various facets of the built environment, the Canadian Institutes of Health Research funded Drs. Paul Villeneuve and Renate Ysseldyk to host a two-day workshop. They invited a diverse group of individuals from many different disciplines to come together with the intention to discuss what is known about dementia, social factors, and the built environment, and to identify emerging areas of research. Several themes arose:

Another Strike Against Air Pollution

Very few studies have evaluated the effects of air pollution on dementia, although a small number of studies in animals suggest there may be a link. However, preliminary analyses of data from the Canadian Study of Health and Aging by Dr. Paul Villeneuve and colleagues did just thatā€” his study aims to characterize the associations between long-term exposure to air pollution and the development of dementia, “”±ō³ś³ó±š¾±³¾±š°łā€™s disease and cognitive impairment. The study includes 10,263 participants, 65 years of age or older with no initial cognitive problems, who were followed for 10 years with three follow-up periods. A total of 1,460 participants developed dementia, 563 participants developed “”±ō³ś³ó±š¾±³¾±š°łā€™s disease and 883 developed cognitive impairment by the end of the 10 year follow-up period. To determine whether air pollution had an effect on the development of these diseases, measures of ground-level and Nitrogen Dioxide (NO₂) were assigned to each participant using their residential postal code. Initial findings demonstrated positive associations between these measures of outdoor air pollution and developing dementia and “”±ō³ś³ó±š¾±³¾±š°łā€™s disease. With each increase of PM_2.5 by 10Āµg/m³, the risk of developing dementia and “”±ō³ś³ó±š¾±³¾±š°łā€™s diseases increases by 32% and 17%, respectively. As an annual average in 10 Āµg/m³ represents, in 2011, the difference between London UK and Ottawa, or Berlin and Montreal (). Ā The strength of association for these outcomes is similar to widely reported findings between air pollution and cardiovascular disease.

Green Space, Green Space, and More Green Space

As previously discussed, there is no known cause of dementia; however, there have been several risk factors associated with its development. Both physical activity and social interactions have been identified as potential factors influencing the development of dementia. A moderate level of physical activity has been identified as a protective factor against dementia, especially in those individuals who have some type of genetic predisposition (Canadian Study of Health and Aging, 2002). Likewise, social interactions help build an individualā€™s sense of social identity and inclusion, resulting in positive effects on health and well-being (Haslam, Haslam, Knight, Gleibs, Ysseldyk, & McCloskey, 2014). Importantly, these factors may interact with green space. Recent studies have indicated that a greater availability of residential green space increases levels of physical activity (McMorris, Villeneuve, Su, & Jerrett, 2015), decreases exposure to air pollution (Marshall, Brauer & Frank, 2009) and provides an environment where social interactions can be upheld (Bennet et al., 2012), suggesting that green space can help decrease the development of dementia and other cognitive impairments.

Interior Design and Cognitive Health

There is also some evidence that the design of a care home may have an effect on the development of dementia as well as the quality of life and safety of individuals with dementia. Findings from these studies suggest that small-size units, with a smaller number of residents, are associated with less sadness, better quality of life, and can help residents better orient themselves (Crespo, Hornillos, & GĆ³mez, 2013). Interestingly, designing these spaces does not have to be performed by professional teams ā€“ in fact, in an intervention study conducted by Dr. Renate Ysseldyk and colleagues, having residents choose the design of the spaces enhanced their cognitive capabilities to an even greater extent than when staff made those design decisions, along with building their sense of social connectedness (Haslam et al., 2014). Another important feature to consider is safety, especially since individuals with dementia tend to wander ā€“ leaving their homes or facilities without knowing where they are or where they are going. To help deter residents from leaving the facility, long-term care facilities can provide unique doorway designs that mask the entrance to deter the residents from leaving (“”±ō³ś³ó±š¾±³¾±š°łā€™s Knowledge Exchange, 2010). Likewise, creating special interest areas away from main exits and doors helps keep residents away from these entrances (“”±ō³ś³ó±š¾±³¾±š°łā€™s Knowledge Exchange, 2010). Taken together, this research suggests promising avenues for the role of architecture and design, as well as empowering residents in design decisions, that may help prevent or alleviate the symptoms of dementia.

Where Do We Go From Here?

Clearly the built environment, and the social interactions it can facilitate, plays an important role in shaping our health profile. But we are only at the beginning stages of fully understanding the magnitude it can have on our psychological health and cognitive functioning. This CIHR sponsored workshop was able to identify several emerging research questions. Future studies should consider how the built environment can be designed to enhance the positive social determinants of health and prevent the development of dementia. The meeting brought together a number of experts in these different areas who are interested in working together to do just that. In the meantime, the next time you are in the market for buying a house, keep in mind how the location may affect your healthā€¦ and who knows, maybe keeping your bed away from the door wonā€™t hurt either.

Based On:

Villeneuve, P., & Ysseldyk, R. (2015). The Built Environments and Dementia: An Interdisciplinary Approach. Workshop. ŠÓ°ÉŌ­““ University, Ottawa, ON, June 19-20, 2015.

Alzeihmerā€™s Knowledge Exchange. (2010). Retrieved from: http://alzheimersocietyblog.ca/2012/01/do-you-know-what-the-alzheimer-knowledge-exchange-ake-is/.

Bennet, S. A., Yiannakoulias, N., Williams, A. M., & Kitchen, P. (2012). Playground accessibility and neighbourhood social interaction among parents. Social Indicators Research, 108(2), 199-213. doi:10.1007/s11205-012-0062-4

Butler, R., & Radhakrishnan, R. (2012). Dementia. BMJ Clinical Evidence, 2012.

Canadian Study of Health and Aging. (2002). Retrieved from: http://www.csha.ca/.

Crespo, M., Hornillos, C., & GĆ³mez, M. M. (2013). Dementia special care units: A comparison with standard units regarding residents’ profile and care features. International Psychogeriatrics / IPA, 25(12), 2023. doi:10.1017/S1041610213001439

Dudgeon, S., Alzheimer Society of Canada, & RiskAnalytica. (2010). Rising tide: The impact of dementia on Canadian society: A study. Toronto, Ont: Alzheimer Society of Canada.

Elbaz, A., Dufouil, C., & AlpĆ©rovitch, A. (2007). Interaction between genes and environment in neurodegenerative diseases. Comptes Rendus – Biologies, 330(4), 318-328. doi:10.1016/j.crvi.2007.02.018

Haslam, C., Haslam, S.A., Knight, C., Gleibs, I., Ysseldyk, R., & McCloskey, L. (2014). We can work it out: Group decisionā€making builds social identity and enhances the cognitive performance of care residents. British Journal of Psychology, 105(1), 17-34. doi:10.1111/bjop.12012

Marshall, J. D., Brauer, M., & Frank, L. D. (2009). Healthy neighborhoods: Walkability and air pollution. Environmental Health Perspectives, 117(11), 1752-1759. doi:10.1289/ehp.0900595

McMorris, O., Villeneuve, P. J., Su, J., & Jerrett, M. (2015). Urban greenness and physical activity in a national survey of Canadians. Environmental Research, 137, 94-100. doi:10.1016/j.envres.2014.11.010

Toronto Public Health. (2015). The Built Environment. Retrieved from: http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=d06e23bf6d481410VgnVCM10000071d60f89RCRD.

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By Anna Tomczak, Department of Health Sciences, ŠÓ°ÉŌ­““ University

It seems like we, as a society, are constantly being warned against disease-causing products, whether it be the dangers of BPA found in our water bottles or the associated risks of getting vaccinated. Rarely are these ā€œfindingsā€ of danger found to be true. In fact, such warnings tend to create more public disorder than the alleged dangerous products themselves. Recently however, studies have indicated that what was previously considered as ā€œsafeā€ levels of (PM_2.5), may actually be associated with an increased risk of adverse health effects.

Gary Simmons Photography

Fine particulate matter consists of airborne particles found in polluted air, resulting from chemical reactions in the atmosphere and through fuel combustion. Exposure to this particulate matter has observable effects on human health, and it has been identified as one of the top 10 health risks worldwide. Long-term exposure to PM_2.5 has been specifically linked to increased risk of cardiovascular disease, diabetes, hypertension, and non-accidental mortality. In 2013, fine particulate matter was declared a human carcinogen by the International Agency for Research on Cancer due to findings of increased risks of lung cancer reported in several epidemiological studies Alarmingly, more studies are finding that concentrations of fine particulate matter at levels less than 10 Āµg/m³ have a direct association on the risk of both cardiovascular disease and non-accidental mortality. These findings have important public health implications as these levels of pollution are common in most Canadian cities.

Findings from a recent paper provide more evidence that these low levels of air pollution are affecting Canadiansā€™ health. Villeneuve et al. (2015), conducted a study looking at long-term exposure to fine particulate matter air pollution and mortality among Canadian women. The study followed 89,835 healthy women between the ages of 40 and 59 for 25 years. They grouped women according to their exposure to PM2.5 at their homes, and compared mortality rates across different levels of pollution. They were able to adjust their comparisons for other risk factors that are associated with mortality such as smoking, obesity and other characteristics, They assigned air pollution exposures by taking satellite-based measures of PM_2.5 between the years 1998 and 2006 and linked these to participants postal codes. They were able to determine which women died, and their cause of death by linking participantsā€™ information to the Canadian Mortality Database

Image courtesy of samarttiw at FreeDigitalPhotos.net

As with any study looking to define a relationship between an exposure and an outcome, outside factors that may play a role in explaining the outcome must be considered and controlled for. Building off of previous studies, where socio-demographic and occupational characteristics were analyzed with regards to PM_2.5 exposure and mortality, Villeneuve et al., looked to expand the already existing knowledge through the analysis of four additional factors: smoking, obesity, place of birth and whether the participants had moved within 5 years of the initial recruitment. Furthermore, dose-response models were created to better understand how the concentration of PM_2.5 relates to mortality.

This is great, but what does this all mean? Are we in danger or not? The study revealed several key findings that shed the impact of fine particulate matter on daily life.

Residential PM_2.5 Concentration

Using the satellite-based surface readings of PM_2.5 and the residential postal codes of the participants, the median exposure to PM_2.5 across all participants was determined to be 9.1Āµg/m³, which is considered to be a fairly low concentration.

Are Low Concentrations of PM_2.5 Dangerous?

Unlike the tales of the dangers of BPA in water bottles, low doses of fine particulate matter do in fact increase the risk of cardiovascular disease, specifically ischemic heart disease and nonaccidental mortality. Villeneuve et al estimated that an increase of 10 Āµg/m³ of PM_2.5 increases the risk of ischemic heart disease and non-accidental mortality by 30% and 15%, respectively. Considering that such low doses were thought to be safe is shocking! Even after adjusting for the socio-demographic, occupational and risk factors, these results remain the same, indicating that these mortalities can be explained by the exposure to fine particulate matter. These results were further confirmed by the dose-response model that indicated a linear trend between PM_2.5 concentration and ischemic heart disease mortality, where an increase in exposure leads to an increase in risk of mortality. The findings of this study are very similar to risk estimates obtained from a separate Canadian cohort study that was done using census data.

Another Reason to Stay in Shape

Interestingly, and maybe not so surprisingly, obesity was found to play a role in modifying the relationship between exposure to PM_2.5 and mortality by cardiovascular disease. Associations between PM_2.5 and mortality were found to be stronger for obese women compared to nonobese women. This suggests that women who are more obese may be more susceptible to the harmful effects from long term exposure to air pollution.

Was I Born in the Wrong Country?

Luckily, where you are born does not have an effect on the risk estimates of mortality outcomes. Women who were born outside of Canada had no observable disadvantage or advantage compared to those born in Canada. Similarly, having moved in the first five years of the study also did not have an effect on the risk estimates.

This study adds to the findings of recent studies showing mortality impacts at air pollution levels commonly observed in Canadian cities. Additionally it expanded this knowledge by identifying obesity as an important modifier in this relationship. It becomes quite evident that even low concentrations of fine particulate matter can have a visible impact on human health. Having these new insights on the influences of fine particulate matter at very low levels begs the question of what can be done to lower pollution levels, and how low can we go. Because low concentrations of PM_2.5 have an observable influence on human health, new policies may need to be put into place to help protect the population.

These findings are yet another indication that the pollution we help create, whether it be through our reliance on industrial processes, or our own driving habits, has a significant impact on our health. It is important to remember that even though that paper mill down the street may seem harmless, it can be quite dangerous.

Based on:

Villeneuve, P. J., Weichenthal, S. A., Crouse, D., Miller, A. B., To, T., Martin, R. V., . . . Burnett, R. T. (2015). Long-term Exposure to Fine Particulate Matter Air Pollution and Mortality Among Canadian Women. Epidemiology. doi: 10.1097/EDE.0000000000000294

Ontario Ministry of the Environment and Climate Change. (2010). Fine Particulate Matter. Retrieved from:Ā 

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