I vermicompost within a 500 square ft apartment and have been considering adding another bin. I often wonder if indoor vermicomposting has an impact on indoor air quality. After all it relies on decomposition and molds to break down food… I would be interested in hearing your thoughts on this… Thanks!
This is a very interesting question, and – like my responses to so many other questions relating to this quirky field of endeavor, I have to say…it depends!
Firstly, I will say that (in my humble opinion) a well-managed worm bin – or even multiple systems – shouldn’t create any air quality issues at all! If you consider the sort of decomposition processes that take place in say a forest, for example – there’s virtually no way that would ever be a hazard (unless you have some sort of allergy, which we will come back to in a minute). If anything, that sort of earthy-smelling decomposition would likely be good for you!
So what does “well-managed” mean?
In basic terms, you should have a system containing a lot of bedding materials, such as shredded cardboard/newsprint, and a moderate amount of food materials. The foods should be buried, and I highly recommend a thick cover layer of bedding in the system as well.
In contrast, a poorly managed system might be one that is receiving far too much food waste and/or one in which a lot of food is left exposed. Certain types of food – eg starchy wastes like bread – are much more prone to mold growth, and if you leave them intact and completely exposed you can end up with a lot of mold spore production.
Optimizing waste materials for worm consumption can also help – eg chop things up, freeze/thaw and mix different wastes together etc. This (combined with feeding in moderation) helps the worms to keep on top of fungal growth, and it is unlikely you’ll end up with spore release.
For those with a wee bit more experience, I recommend the use of high quality “living materials” – it’s almost like an earthy, “forest floor” injection for your worm bin – and can be fantastic for helping to keep things balanced (and avoiding mold outbreaks).
OK – getting back to the topic of mold allergies…
I am by no means an expert, so my cautious recommendation would likely be for anyone highly-sensitive to spores etc to avoid indoor vermicomposting completely – just to be on the safe side. The assumption here is that these are the same sorts of people who wouldn’t be able to visit a farm, dig around in a compost heap etc.
Or at least to do your own due-diligence – talk to actual experts etc.
Hope this helps!