Science Buddies: "Ask an Expert"

Hello!

I am doing an environmental engineering project in which I'll be creating a new air filter and testing its performance on various indoor air pollutants. However, I'm having trouble coming with a way to actually test the filter's effect on pollutants. Originally, I was planning to choose multiple pollutants (VOCs and bioaerosols) to test based on their prevalence (how common they are), significance (how harmful), and feasibility of testing (cost). As a compiled a list of potential pollutants (radons, carbon dioxide, carbon monoxide, particulate matter, nitrogen oxides, formaldehyde, ozone, VOCs [acetone, toulene]), I realized there were multiple problems in testing these pollutants that I wasn't sure how to address:

1. Source of pollutants- Where would I find or produce these pollutants (while still complying with safety regulations, especially as most of these pollutants are toxic)? How would I "produce" enough of these pollutants so that I could actually measure the difference with/without my filter? The best solution would to work in a lab or test in a facility that already has a lot of pollutants (i.e. factory), but I have no access to lab and I'm not quite sure how I'd work out the latter option.
2. Cost & Time- Most conventional ways to monitor and test pollutants are extremely expensive, ranging from hundreds to thousands of dollars.
2. Accurate results- while I was able to find home testing kits (such as radon testing kits) and "diy" monitors, I'm concerned that these kits wouldn't give accurate results. I also wouldn't be able to continuously monitor the air quality (pollutant level as a function of time) since most of these kits need to be sent back to a lab for results.
3. How to test bioaerosols? One of my most important applications was that this filter would ultimately be able to be used in hospitals or homes against bioaerosols (bacteria, viruses, pollen, dander, dust). However, there are very strict safety regulations regarding the use of bacteria and bioaerosols, so I'm not sure how I would test this?

I understand that this was a very lengthy, problematic question, but I would appreciate it greatly if someone could offer some guidance ASAP. Thank you so much!

-Annie

Hi Annie,

While you have a great idea in trying to develop filters for a variety of airborne substances, I think you need to narrow down your focus to just one type of pollutant that you can measure. As you said in your post, the analysis of most of these substances is difficult, expensive and time-consuming. What you want is a filterable substance that you can easily and quantitatively measure yourself.

Particles such as pollen or dust might be the best things to try filtering because you may be able to test your filters simply by weighing them before and after filtering air for a certain period of time.

I think you will need to make some device to pump air through a measured area of filter material. In order to compare different filter materials you need to use the same surface area of filter, constant air flow and measured time. You could build an air sampler out of plexiglas with a number of holes of the same size and a small air pump to pull air through. Weigh your filter materials, position them tightly over the holes and then let the pump run for several hours or maybe even a day. Remove the filters and weigh them. the increase in weight would be the amount of particles that filter removed from the air.

I hope this helps. If you have more questions, please let me know.

Sybee