Hi Roasters. I’m providing some air quality index (AQI) information that I think will interest you. I recently acquired an AQI analyzer because I was curious about exposures while roasting.
First some information about my setup: I use an in-line fan exhaust system that vents to the outside. I roast in my garage so I always have a big floor fan circulating a lot of air for my own comfort (it’s hot in Florida in the summers!) I am including a picture of my setup.
In short, the AQI meter indicates that everything is A-OK while roasting with my setup (see the still photo of the meter)
. What really surprised me was what the meter indicated during dumping of the roasted beans; the air quality deteriorated rapidly well beyond the point where the analyzer went into alarm. I have included a photo showing the meter at its highest reading.
In the photo you will see that the bottom/center number is the AQI, the bottom/right number on the meter indicates Particle Matter less than 10 microns (PM10), and the number right above PM10 is the PM2.5 indicator (Particle Matter less than 2.5 microns. Particles this small can enter the lungs and even the blood stream. This photo was shot with the meter sitting within a foot of the cooling bowl.
I repeated the measurement on a subsequent dump with the meter closer to my body, or within 2-2,5 feet. The photo of that dump will show that the AQI near me was still not good but the analyzer did not go into alarm.
In the future, I will keep as much distance as I can between myself and the cooling bowl while still being able to stir the beans, and will wear a mask like those we’ve all worn during the Covid pandemic.
Finally, I found an article regarding a study performed by an environmental agency at a coffee roasting and packaging facility. (https://www.cdc.gov/niosh/hhe/reports/pdfs/2016-0080-3324.pdf In short, all employees involved in the process showed above acceptable exposure limits for various compounds related to coffee roasting and packaging. What I gather from this is that I should do my best to limit my exposure while enjoying my craft! Maybe you will come to the same conclusion.
Do you have a vent hose from the back of your cooling tray to vent out? If not, I wonder what the AQI would read if you have a hose that directs the fumes outside. In my setup I have a hose from the cooling tray to direct the fumes to my range hood vent that is on during roasting. I think many of us have a hose to vent out the cooling tray fumes.
I have an exhaust tube on my cooling tray, and I also see out of healthy region AQI levels when dumping beans, but all good when roasting. I don’t have as fancy of an AQI meter, but I do have a meter that is connected to my air purifier that lets me know when things are out of healthy region. Currently I’m using an inline 6 inch AC Infinity, which adapted to pull from 4 inch ducting and split 50/50 between the cooling tray and exhaust area of the roaster. I think it would be possible to create some sort of adapter that could pull some air from just under the exit of beans from the roaster and also from the normal exit from cooling tray and then y-into a 4 inch male exit. I have a picture in my head, but that’s hard to explain. Think of something like a hardwood floor vacuum cleaner attachment, that might have a curve around the roaster exit to get as close to the exit as possible, which would then meet up with the 4 inch coming out of the cooling tray.
Not only the smoke from the beans, but the plastics can heat up significantly enough that I wonder about fumes from those. Though if you smell plastic burning, it is probably a sign that your roaster is not working properly.
Thanks for sharing about the air quality and it is a good reminder to make sure ventilation is a priority.
Air quality is something I have been interested in for many years. Living on the West Coast, we now have a fairly regular “fire season” and I have been tracking indoor and outdoor air quality to help minimize my family’s exposure during smoke events.
So after reading this post last year, I moved one of my sensors into the roasting corner in my garage. My venting strategy involves two Cloudline fans vented to the outside. The 4" fan is dedicated to the cooling tray and runs on full blast when I’m dumping beans. I run the 6" fan for the bullet exhaust on about 50% speed.
To my mild dismay, there is still a noticeable spike in pm2.5. I do see similar spikes for air quality in my kitchen when cooking (or even higher) so this isn’t horrible, but I was hoping for it to be very low or undetectable.
I need to log my time more carefully during my next roast to try and mark on the graph when the beans are dropped. I suspect most (maybe all) the pm2.5 is released at that point.
Uh oh, this is rather worrisome. I thought venting the roaster outside and adding a dedicated hose to the cooling tray would be enough, but it seems like it needs more work.
To the person who suggested wearing an N95 mask while dropping the beans, would that be sufficient to filter out the small particles and VOCs? I think you’d need something more robust, such as a 3M respirator fitted with these cartridges:
I just invested in an AQI monitor from Amazon to test my own environment and report back here with some numbers.
Guys, you might be worrying about nothing.
Would this air quality reading be any different to that from any other baking, frying or cooking process we do as part of everyday food preparation ?
If what you are measuring is temporary and you are only exposed to for just a few seconds as opposed to being part of an ongoing and lasting climate then I wouldn’t worry about it.
Being close to a charcoal bbq or a camp fire might be worse for your health than roasting coffee on this small and infrequent scale.
I wouldn’t describe my feelings towards indoor air quality as worried per se. More that I am interesting in fully understanding when and how much particulate (and VOCs) pollution I am exposed to as part of my daily life.
Cooking, especially frying, will create a massive (90-120+) spike on a sensor. As will my spouse blow drying her hair. Also, we have many days (over a month once) when the outside air quality was well into the 60+ μg/m3 range. I can’t even imagine the numbers experienced around a campfire or a charcoal bbq.
Also, there has been some research indicating that the particulate and VOCs released during roasting may be especially bad for you.
I think it is something to be aware of and to take reasonable steps to minimize, but as an infrequent home roaster, I don’t think I would bother with a mask.
Your spouse probably has a blow dryer with an ionizer, and any ionizer will release ozone, so that’s what’s being picked up by your monitor.
Roasting anything, not just coffee. gabyritaseek.qiAO has said everything already, but I’d like to add that, when roasting or frying anything, the amount of toxicity will be determined by the level of roast. So, if you like your coffee burned beyond recognition, it will be especially bad for you. The food that you over roast or over fry will add other risks when ingested. Coffee won’t, as long as you brew it, but if you eat burned beans it will have negative effects.
