The pandemic situation has generated a lot of interest and activity in UV disinfection, which has been keeping me busy. Whether it’s for masks, air, surfaces or whatever, there are lots of things getting posted and promoted for using UV. There seem to be an overwhelming number of devices and designs being suggested or sold online. Unfortunately there are also a lot of misconceptions, errors and possibly fraudulent claims being promoted. I’m not going to try and address each and every device (there are too many!), but I can provide some basic ideas that one should know or ask about when considering UV devices. If the supplier can’t readily provide answers or details, then something is possibly wrong. Here are a few key confusing points:
Continue readingInformation
Classroom Air Cleaners?
Schools of all sorts are looking for ways to re-open while minimizing coronavirus transmission risks. Harvard University’s School of Public Health recently issued a downloadable document on “Schools for Health”. In it they suggest a number of administrative and engineering approaches for reducing virus transmission in a classroom and school setting. It’s interesting and worth a look.
Since I teach and do research in some aspects of HVAC (Heating Ventilation and Air Conditioning) and indoor air quality, those parts of the report caught my attention. They are suggesting that people consider using portable air cleaners in the classroom, especially in situations where the HVAC is non-existent or poor. They don’t give a lot of numerical detail behind that recommendation, but it’s fairly easy to work it out. So I’ve done some quick calculations to see where air cleaners might be useful from a more quantitative perspective.
Continue readingDo Face Masks Work?
“Plus ça change, plus c’est la même chose” (the more things change, the more they continue to be the same thing, attributed to Jean-Baptiste Karr).
In our current pandemic situation there has been lots of confusion, uncertainty and general ignorance on the subject of face masks and reduction of disease transmission. In the screen capture I show the introductory paragraphs of an article published over one century ago, just as the so-called “Spanish Flu” H1N1 pandemic was probably starting but not yet recognized.
Continue readingCoronavirus drifts through the air in microscopic droplets – here’s the science of infectious aerosols
Here’s a nice summary article about aerosol viral transmission, by a mechanical engineering professor. The physics of aerosols is a foundational concept in air pollution control.
Aerosols are the tiny particles of liquid and material that float around in our environment. When they come from an infected person, they may be a significant source of coronavirus transmission.
The Future of Chemical Engineering
Sometimes I see people getting concerned about future prospects for chemical engineering careers, usually because of some downturn in the oil and gas markets. I guess we should never stop emphasizing that chemical engineering is much more than oil, gas, and petrochemicals! There is also food, pharmaceuticals, alternative energy, environment, safety, consumer products, plastics, minerals, metals, paper & fibers, etc….
Actually, the next 30 years is probably going to be a very exciting and technically challenging time to be a chemical engineer. The world needs people with the innovation skills to handle new materials and energy processes more than ever. Why is that? Here are a few quick thoughts…
Continue readingHand Sanitizer Blending
Soap and water is a preferred choice for hand hygiene and reducing microbial and viral contamination. However this isn’t always convenient or available when out walking or shopping for necessities, so the next best thing is a hand sanitizer formulation. The nice commercial ones are in short supply, but it is relatively easy to blend your own if you can access the ingredients. Blending chemicals safely is another chemical engineering specialty. Here’s a recipe for small volumes for home use, with some discussion on the physical chemistry basis for the various components.
Continue readingOnline Teaching Experience
The last two weeks of our lectures for the Winter term (last two weeks of March) were all done “online”, since the on-campus activities were shut down. This was an interesting experience, especially since we only had a week to prepare. It took quite a few hours of effort to figure out the online technology and work out different ideas and approaches before starting.
For my Air Pollution Control course, I used Webex to deliver the last two weeks of lectures live, sort of like some Webinars I’ve done in the past. These lectures were also recorded so that students who couldn’t attend “live” could look at them later. I liked the live aspect, so that students could submit questions via the chat function as we went along. I think that the ability to ask and answer questions is important, and you lose something when it can’t be spontaneous.
Luckily for me, the last two weeks of material in my course was relatively easy to adapt for online delivery. It was largely descriptive, not so much mathematical or technical. Some things that I would have normally done on the board in a classroom I had to adapt into a powerpoint deck, but it wasn’t too bad.
Delivering a whole course online is another matter, which my colleagues are scrambling to do for the term starting in May. Doing it really well takes substantial development work and a pedagogical re-think of virtually everything about the course. From what I’ve read, properly developing a truly excellent online course can take many months of preparation, audio/video recording, and editing.
Unfortunately we haven’t had a lot of time to do this, but our instructors seem to be seriously working on it as best as they can. I don’t have any courses to teach in the May-August term, but I’m keeping a close eye on how it’s done in case we are still teaching online in September when I teach another course. The university has developed a website where we can find some suggestions and other resources for online teaching. I hope we can have classroom teaching again in September, but there are some doubts and I guess we have to be prepared for anything at this stage.
N95 Masks and Re-Use
Recent pandemic developments have strained the supply of N95 filtering facepiece respirators (FFRs), which protect users from particles and aerosols in the air that they breathe. Technically, they must filter out at least 95% of 0.3 micrometre particles.
Normally these are meant to be single-use devices, and are removed and disposed of in a secure way to prevent infection transmission. However, with supply shortages people are considering or resorting to re-using these FFRs, possibly with some sort of chemical or physical disinfection process. Disinfection processes are never 100% effective, so this is not a great option, but I guess it’s better than having no protection.
One disinfection method that I’m very familiar with is UV-C disinfection, having done research in the area of photochemical processes for several decades. There is published literature available demonstrating reasonable disinfection success for UV when applied to N95 FFRs, so this may be an approach to consider if necessary.
I’m working on an overview of this literature (draft version now available at this link), but I’m happy to consult (pro bono) with health care institutions that are considering UV applications to deal with their situations (wanderson@uwaterloo.ca).
Applying to University: Done Your Homework Yet?
For those applying to university for Fall 2020 admission, there is some homework you should have done, or at least started by now. Arguably, this is probably the most important homework that you have, even if no one has explicitly assigned it or told you to do it. Properly done, this homework will make success in university more likely. So what is this homework?
Continue readingHHT Awareness Month
Every day, week and month has a charitable or other cause associated with it. June is apparently Stroke Awareness Month in Canada, which is a good thing to be aware of because so many people are affected by stroke at some point, directly or otherwise. June is also HHT Awareness Month, although not many people have heard of it. That’s mainly because HHT is one of those less common conditions listed as a “rare disease” in the NIH GARD database and elsewhere. It is actually not technically that “rare” as it is believed to affect about 1 in 5,000 people, although possibly less than half of them know it.
HHT is Hereditary (i.e. genetic) Hemorrhagic (i.e. bleeding) Telangiectasia (i.e. small blood vessel malformations in the skin and mucosal linings), also known as Osler-Weber-Rendu Syndrome after the Canadian-German-French physicians who described it in more detail in the late nineteenth and early twentieth centuries.
The most common and noticeable symptom is frequent and spontaneous nosebleeds. Other complications include gastro-intestinal bleeding, chronic iron-deficiency anemia, stroke, heart and/or liver failure, and oxygen deficiency. The underlying reason is that a genetic mutation creates a problem with one of the proteins involved in blood vessel formation, leading to malformations in the skin, nose, liver, lungs, brain, intestines and elsewhere. This mutation is autosomal dominant, meaning that there is a 50% chance of passing it on to a child.
Although it is incurable, the symptoms and complications can be managed in a variety of ways, depending on the extent and degree of severity. There are HHT treatment centres scattered across North America and Europe, as listed on a website. The trick is recognizing that someone might have HHT, as many family physicians have never seen it and may not recognize the symptoms if they do see it. This is one reason why fewer than half know that they have it. Therefore the need for awareness, so that people can be diagnosed and treated before serious complications occur. In Ontario, there is an HHT Treatment Centre at St. Michael’s Hospital in Toronto (you need a referral from your family physician).
So if you or someone you know has frequent nosebleeds for no obvious reason, or unexplained iron-deficiency, check out the curehht website and consider following up with your physician, especially if it seems to run in the family.
A Professor in Waterloo Engineering 