Cruise Ship Air Quality

An interesting news story about the measurement of air quality on cruise ships appeared recently.  Specifically, it dealt with the concentration of ultrafine particulate (UFP) matter in the air on four cruise ships, measured by a researcher from Johns Hopkins University.  UFP is invisible matter with diameters of around 100 nanometres (nm), which is about  1,000 times smaller than a human hair, and it is implicated in airway inflammation and effects on other organs in the human body.  Being interested in air quality, I looked up the actual study report which you can also read here.  Here is my take on the work and meaning… Continue reading

Cannabis Air Emissions



With recent moves to permit sales of cannabis in Canada and some U.S. states, commercial operations are popping up in various locations.  Whenever new industries emerge, there are often new environmental impacts to consider and air pollution seems to be an increasingly common problem with cannabis too.  Not from smoking, but rather from the greenhouse operations where it is grown under lights in high-density conditions to save space.  It turns out that these intensive grow operations can have vented air emissions that are rather smelly, as this one news item describes.

Like all plants, cannabis emits volatile chemical compounds at various stages in its growth.  Some work has been reported in research literature, identifying over 200 chemicals in the air, although I suspect that paper missed a lot of odorous sulfur compounds that are often associated with “skunky” smells.  A lot of the odor compounds are terpenes or their relatives (e.g. limonene, pinene, linalool), and the paper mentions cymene, benzaldehyde, nonanal, and decanol as key odor chemicals.  None of these compounds are particularly hazardous (at least at the normally low concentrations found around plants).  None of them are specific to cannabis either.  Lots of them are produced by various plants, in varying amounts and combinations.  A lot of plant-based essential oils that you can buy contain similar chemicals.

The environmental issue arises if the odor interferes with the neighbouring property and their ability to use and enjoy their property.  The Ontario government website has some information about odors and property-owner rights .  Under Ontario’s Environmental Protection Act (Section 14) odor-emitting industries can get into legal trouble because they are emitting a “contaminant” that causes an “adverse effect”.

From an engineering point of view, the control of odorous emissions like this is not unlike many other industries with odour concerns, like sewage treatment plants, rendering plants, some food manufacturers, and some chemical manufacturers.  The first step is containment, so that odor emissions are not just leaking out of the buildings from a multitude of locations.  If everything can be efficiently captured in one or two well-controlled ventilation systems, then emissions controls can be applied to those vent streams before they discharge into the environment.

It’s not clear at this point what type of emission controls are best for both efficiency and cost points of view.  Usually there are several possible solutions, so engineers have to figure out which one is the most cost-effective.  Standard approaches to odor control run a range of technologies from wet scrubbing to activated carbon capture, to biofiltration and possibly photochemical oxidation.  High temperature thermal oxidation is another option, but probably overkill and too expensive for this application.  One solution may not fit all commercial operations either.  Each location would need a thorough engineering analysis and assessment for a good recommendation, which is something done by chemical and environmental engineers (and some mechanical engineers too).  Companies that rushed into production without doing these assessments may get stuck with expensive retro-fits once the Ministry of Environment comes knocking.

So, with every new “industry” there are issues that come up that may or may not have been anticipated by the business people.  Those issues will keep regulators and engineering consultants busy for a while.

Ontario Climate Change Plan Input

The new Ontario government quickly trashed the beginnings of an approach to reducing carbon emissions and climate change, i.e. a “cap and trade” system in collaboration with California and other provinces and states.

Now the government is looking for input into their promised new and improved approach, which you can provide at .   It’s open until November 16 2018.

A recent report has re-confirmed that we only have until about the year 2030 to substantially reduce carbon dioxide emissions, before the goal of keeping the global average temperature increase to less than 1.5 degrees Celsius becomes physically impossible.  (This is actually not surprising news since it’s been known for many years in the scientific literature, while the world at large continues to do nothing substantial).

Young people, and parents or grandparents of young people, should be commenting because these are the ones who will be inheriting the problem and all of its consequences over the next few decades.

Long-term effects of forest fires pose threats to drinking water

An interesting article about my colleague Prof. Emelko’s research.  I’m somewhat jealous that she gets to fly in a helicopter!

Forest fires are sweeping North America with detrimental environmental, economic and human impacts. A research team, led by University of Waterloo Engineering professor Monica Emelko, will receive $5.5 million from the Natural Sciences and Engineering Research Council of Canada’s (NSERC) Strategic Partnership Grant for Networks to provide new knowledge on the impacts of different forest management strategies on drinking water source quality and treatability.

Source: Long-term effects of forest fires pose threats to drinking water | Water Institute | University of Waterloo

Fireworks and Air Quality

English: The New York City fireworks over the ...

English: The New York City fireworks over the East Village of New York City. (Photo credit: Wikipedia)

As we approach Canada Day (July 1) and Independence Day in the U.S. (July 4), our thoughts turn to the pyrotechnics that are a typical part of the celebrations.  For a chemical engineer, pyrotechnics are a fascinating topic because they rely on rapid combustion reactions and the presence of various elements that give rise to the different colours.  However, my research interests are in air quality and I’m at the Air & Waste Management Association conference in Chicago, so I’m going to review the air quality impact instead. Continue reading

A Burning Issue

Kitchener is a city located next to the city of Waterloo, so close together that it’s hard to tell where one city stops and the other starts.  They are two separate legal entities however, and in Kitchener there is a raging debate about limiting or banning backyard fires (Waterloo banned them some years ago).  The debate boils down to the rights of individuals to use their property as they see fit, versus the rights of their neighbours to clean air.  On technical grounds, I would side with the people who are seeking a ban, based on what we already know about wood fires and air quality. Continue reading