Without an activated carbon filter on the outside to collect dust and other bigg...

		textech on Dec 17, 2020 \| parent \| context \| favorite \| on: Experiments on a $50 DIY air purifier that takes 3... Without an activated carbon filter on the outside to collect dust and other bigger particles your HEPA filters will be utterly useless in only a few weeks. If you keep your windows closed then I guess it could last longer but then you may have CO2 issues.