Any time you want to achieve something great, collaboration and teamwork are a necessity, not an option. You learn this one way or another if you have ever pursued greatness, whether in the form of athletics, entrepreneurship, artistry, or academics. As there will inevitably be obstacles along the way, it would be impossible for one person to know how to solve each and every problem encountered.

In the 1969 book 鈥淚nterdisciplinary Relationships in the Social Sciences鈥�, Donald T. Campbell argues that science is conducted most effectively when researchers from different areas and disciplines collaborate on projects of overlapping interest (Campbell, 1969). As another student blog writer, Joel Sprunger, puts it, At the heart of Campbell鈥檚 idea is that with academic collaboration, we are greater than the sum of our parts. This is the concept that we will be exploring in this blog, based on our experiences in a collaborative research effort to study air pollution in Grenada.

According to the 2017 edition of the , ambient air pollution presents one of the greatest environmental-related health risks. All-cause mortality relating to air pollution rose 5.8% from 4.6 million deaths in 2007 to 4.9 million deaths in 2017, most of which stems from increases in cardiovascular, cerebrovascular, and respiratory disease (Stanaway et al., 2018). While much of the world seems to be dealing with urban air pollution problems, a closer look reveals subtle differences based on geographical location.

Satellite image showing desert dust from the Sahara blowing west across the Atlantic Ocean

Take Grenada for example: they are a non-industrialized island nation that disposes of waste via burial and burning. A relatively large portion of their motor vehicle fleet is quite old, resulting in more fuel consumption, higher greenhouse gas emissions, and greater emissions of carbon monoxide and respirable particles. In addition, on a daily basis, large cruise ships visit the port in St. George鈥檚, Grenada鈥檚 largest town. This poses an environmental health issue as these cruise ships idle their generators to maintain electrical supply. Perhaps the most intriguing component of air pollution in Grenada (and possibly the Caribbean) is the presence of Saharan dust. At certain times of the year, the Caribbean is exposed to masses of desert dust that are transported from the Saharan region of northern Africa. Due to a sustained drought period in the Sahara since the early 1970鈥檚, there has been a sharp increase in the amounts of this desert dust being transported around the world. This component of air pollution is of particular interest because it coincides with a rise in Caribbean respiratory disease since the early 1970鈥檚. Altogether, Grenada and other Caribbean states present an opportunity for better understanding sources of air pollution and their impacts on human health.

Our interest in this project stems from our experiences studying air pollution in the Canadian context. Julia鈥檚 undergraduate thesis involved looking into the impact of street design on local air pollution levels in Halifax, Nova Scotia. She conducted a study collecting baseline data on the levels of air pollutants in the downtown area. From traffic count data, the majority of vehicles present in the study were SUVs and regular cars. The air pollutants she measured for this study were PM _2.5 (particulate matter with an aerodynamic diameter of < 2.5 um) and UFP (ultra-fine particles, particulate matter with an aerodynamic diameter of < 0.1 um), both of which are parameters of traffic pollution from automotive exhaust.

Nick based his undergraduate thesis on studying air pollution in urban areas of Mississauga, Ontario. He took measurements of NO_X (nitrogen oxides), NO₂ (nitrogen dioxide), and NO (nitrous oxide), all of which are indicators of traffic pollution. As is common in most urban areas of Canada, traffic is usually the largest source of air pollution. Using these data, he produced a land use regression model to predict NO_X, NO₂, and NO concentrations in previously unmonitored areas of Mississauga. These predictions were used to estimate health risks for residents of Mississauga based on their exposure to these pollutants.

In addition to the two of us, we were accompanied to Grenada by our respective supervisors (Dr. Paul Villeneuve from 杏吧原创 University and from Dalhousie University), as well as collaborating project members from St. George鈥檚 University (SGU) in Grenada (, , and their respective master鈥檚 students, Tania Khan and Solanie Bogollagama). Just as Campbell鈥檚 model for science suggested, we all had overlapping interests that involved the study of environmental health. In collaboration, we brought separate areas of expertise to the table to make our trip to Grenada a successful one.

Air quality research team composed of faculty and students from 杏吧原创 University, Dalhousie University, and St. George鈥檚 University

Going to Grenada, we had four objectives:

1. To set up PurpleAir monitors (air quality monitors that measure PM) around the island that will take continuous air quality measurements. Setting up these monitors will help us quantify how the Saharan dust affects air quality in Grenada on a daily basis as dust passes through the Caribbean region.
2. To perform mobile monitoring of black carbon (BC) and UFP.
3. To meet with Grenada鈥檚 Medical Officer of Health to explain our plans for this project, secure his support, and start the processes to obtain necessary hospitalization data.
4. To meet with staff of the meteorological office at Grenada鈥檚 Maurice Bishop International Airport to discuss getting access to the climate variable data which they measure (such as visibility, rainfall, wind speed, humidity, and mean sea level pressure).

Our work in Grenada began with meeting Dr. Forde and his master鈥檚 student Solanie at SGU. There we scouted for potential locations for installing a PurpleAir monitor on SGU campus. After realizing that it was difficult to satisfy our requirements for a good monitor location, Dr. Forde suggested an alternate location on the southern tip of the island. This location presented a good environment as it was at high elevation and isolated from human activity, had consistent air flow without the influence of urban pollution, and had access to WIFI which allows us to view current and past measurements on. This marked the installation of the first PurpleAir monitor in Grenada.

View of St. George’s, Grenada

After installing Grenada鈥檚 first PurpleAir monitor, our Canadian research team drove around the island to conduct mobile monitoring for BC and UFP. During this excursion we witnessed high levels of both particle types. This could be due to the several trash disposal trucks, construction sites, and high proportion of diesel cars that we passed during our mobile monitoring. Also, as noted earlier, the automotive fleet in Grenada is aging and produces more emissions than newer, more fuel-efficient vehicles.

During our second day of mobile monitoring we obtained consistently low levels of UFP. It was only from Julia鈥檚 past experience using this technology that she was able to determine the monitor wasn鈥檛 working properly. For example, large diesel trucks driving past us no longer caused spikes in measured UFP. For the monitor to function normally, it relies on a filter cartridge that must be soaked in alcohol before measurements can be taken. Julia made the connection that the high humidity was likely affecting alcohol absorption which could have caused the incorrect UFP measurements we saw that day.

Next on our agenda was to meet with Grenada鈥檚 Chief Medical Officer, Dr. Francis Martin to explain the premise of our project. It helped that Dr. Martin had previously done research on the . A key piece of information that we learned from this meeting was that the hospital records at Grenada General Hospital are paper based. We will need to convert these data to digital records if we want to analyze how daily Saharan dust exposure relates to daily hospital visits for respiratory disease. Fortunately, the two master鈥檚 students at SGU volunteered to do this conversion.

Maurice Bishop International Airport

Later that day we had a meeting with the manager of the meteorological office at Maurice Bishop International Airport. We inquired about getting access to meteorological data for Grenada, and chatted with the meteorologists working there about how they identify periods of Saharan dust exposure. An exciting outcome of the meeting was getting permission to eventually install a PurpleAir monitor at this airport! Permission to install an air pollution monitor at any international airport is incredibly rare. All that was accomplished this day couldn鈥檛 have been done without the meeting arrangements made by Dr. Forde and Dr. Mitchell.

Our trip to Grenada was a productive one. While only one monitor was installed, four more locations (the airport, the Ministry of Health building, the SGU faculty members house, and a spot on Grenada鈥檚 neighbouring island, Carriacou) were identified and with the help of the SGU team, four more monitors will be installed. The mobile monitoring of BC and UFP that we completed can be used as a baseline for further research related to these particles. Moreover, as there is minimal research on the relation of BC and UFP, and this study will help fill in that knowledge gap. In addition, the prospect of installing a PurpleAir monitor at the Maurice Bishop airport is novel.

Collaboration is what bound this project together, with each individual bringing their own expertise to the table. There was also specific knowledge about the island learned by talking with locals; this aided immensely in finding suitable locations to install the PurpleAir monitors. The success of this project will rest on the partnerships that have been established between universities. Thank you to everyone who made this project possible and to 杏吧原创 University for the International Seed Grant that was awarded to Dr. Villeneuve to provide funding support to this research.

Nick is a 1^st year M.Sc. student in Health Sciences at 杏吧原创 University in Ottawa.

Julia is a 4^th year B.Sc. student in Earth and Environmental Sciences at Dalhousie University in Halifax.

References:

Campbell, D. T. (1969). Ethnocentrism of disciplines and the fish-scale model of omniscience. In M. Sherif & C. W. Sherif (Eds.), Interdisciplinary relationships in the social sciences. Routledge.

Sprunger, J. G. (2017, December). The benefits of engaging in collaborative research relationships. APS Observer. https://www.psychologicalscience.org/observer/the-benefits-of-engaging-in-collaborative-research-relationships

Stanaway, J., Afshin, A., Gakidou, E., Lim, S., Abate, D., Abate, K., 鈥� Abrham, A. (2018). Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990鈥�2017: A systematic analysis for the Global Burden of Disease Study 2017. The Lancet, 392(10159), 1923鈥�1994.

Wittig, R., K枚nig, K., Schmidt, M., & Szarzynski, J. (2007). A study of climate change and anthropogenic impacts in West Africa. Environmental Science and Pollution Research, 14(3), 182鈥�89.

By Amanda Pappin, Dept. of Civil and Environmental Engineering, 杏吧原创 University.

We have all experienced the law of diminishing returns. It shows up in various scientific disciplines and in our everyday lives. Weight loss is one example that often comes to mind. If you cut your food intake by a fixed amount, initially weight comes off quickly. But with each pound that disappears from the scale, it seems that you have to work even harder to lose the next. Your diet hasn鈥檛 changed, and other factors like exercise are the same as before, but that scale just isn鈥檛 budging. Frustrating, right?

Well, the law of diminishing returns also applies to various topics in economics. At least that鈥檚 what we thought was the case for air pollution economics.

Air pollution poses a significant challenge to environmental managers because what is emitted from the tailpipe of a car, or the stack of an industrial facility, can undergo profound changes in the atmosphere before affecting the air we breathe. Some of the major pollutants that pose risks to our health are not emitted directly, but rather formed in the atmosphere through complex physical and chemical processes. These include pollutants that we often hear about, such as ozone or small airborne particles (particulate matter or PM). Epidemiologists have shown that both pollutants affect human health and increase our risks of illness and even death.

For a long time, economists who study air pollution have believed that the societal payback of reducing pollutant emissions is a battle against diminishing returns. Cleaning up polluted air brings large benefits to our health and the environment. Cleaning up less polluted air by the same amount yields much smaller benefits. Economists have argued that the environment has a natural ability to cleanse itself of pollution 鈥� an ability that works best when pollution is at low levels. As the air becomes more polluted, the environment becomes overwhelmed and cannot remove added pollution as effectively.

My colleagues and I at 杏吧原创 University have tested the validity of the theory of diminishing returns as it relates to air pollution. For the first time, we attached numbers to the benefits of reducing emissions to see how they change as we strive to emit less pollution. Our work, just published in the , sheds new light on the topic.

We used a numerical air quality model, infused with epidemiological and economic data, to estimate the benefits of reducing emissions on a per-ton basis. We defined 鈥渂enefits鈥� as the number of deaths avoided in the population because of reduced ozone, which we converted to dollar values. We focused on the benefits of reducing emissions of nitrogen oxides (NO_x), which are major players in formation of ground-level ozone. NO_x is emitted from motor vehicles and industrial facilities when air comes into contact with high temperatures in fuel combustion.

Our objective was to test whether the per-ton benefits of reducing NO_x emissions decline over time, as environmental economists have suggested. And we found just the opposite. We showed that instead, benefits increase substantially as we continue to emit less. In other words, each additional ton of NO_x emission reduction becomes more beneficial than the previous ton. While looking for diminishing returns, we instead found compounding benefits!

Los Angeles smog

We found that, on average in the U.S., reducing NO_x from vehicles yields benefits of $13,000 per ton of NO_x. On an average per-vehicle basis, the price tag of NO_x emissions can be as high as $870 per year. This number varies depending on where the vehicle is driven, with benefits tending to be larger around populous urban areas than in the countryside. What about diminishing returns? On average, the benefits of reducing NO_x emissions would almost double if we reduce emissions across the country by 60%. Further, if we reached a level of zero man-made emissions, this benefit would quadruple, on average, yielding benefits of $51,000 per ton. The 4-fold average increase in benefits means that adjusting our way of life not only benefits society now, but will also bring benefits for the future. Every dollar that we spend to clean up our air makes the next dollar invested even more valuable.

So why do our findings disagree with the conventional view of diminishing returns in economics? It comes down to a lack of data, resources, and models to assess the adequacy of the theory in question. Only recently have engineers and atmospheric scientists used their comprehensive numerical models for economic applications. And those who have done so had not fully explored the assumptions used in this theory.

To an atmospheric chemist or air pollution scientist, the idea of diminishing returns in air pollution is counterintuitive for pollutants like ozone. Ozone is formed through photochemical reactions in the atmosphere, and its formation depends on how much NO_x and other pollutants are emitted. In polluted air, each emitted NO_x molecule has to compete with many others to form ozone. As the air becomes cleaner, and NO_x less abundant, these molecules are in higher demand. It is for this reason that our results come as little surprise to researchers in atmospheric chemistry and air pollution. But for economists, our findings are surprising, and frankly, a bit bizarre.

A challenge facing environmental managers is that while cleaning the air entails indisputable health and environmental benefits, doing so also costs money. Not only does it cost money, the cost increases as we emit less and less, and at some point, surpasses the expected societal benefits. Economists argue that it is to society鈥檚 benefit for environmental policies to progress to the point of equilibrium where incremental benefits equal costs, and no further. The question of whether benefits diminish or compound is one of great importance to finding this target level of emission reduction. Under the long-held view of diminishing returns, there is less incentive to keep reducing emissions, and the point of equilibrium is closer to our current habits. Our findings offer a new perspective. Compounding benefits provide further incentive to reduce emissions, and to keep reducing, towards an equilibrium point further down the policy trajectory.

So while you opt more and more to commute by bike or by foot to achieve that next pound of weight loss, know that society will increasingly benefit as you do.

This blog is based on:

Stream image courtesy of Evgeni Dinev at FreeDigitalPhotos.net