An aversion to spraying insecticides is well warranted in this situation because it would be ineffective (in addition to the human health risk). If these insects are darkling beetles, they do not pose a hazard to you or any pets/children/houseplants/etc. 

I have a couple questions that will help recommend more specific control measures. Are you able to get a picture of these beetles? Do you have any pets? Do you live in close proximity to livestock?

The beetles are likely making their way into the home through unsealed cracks. These are often around doorways/windows, but they can also occur in walls/around vents. I doubt they are coming through the vents themselves, unless the in-take valve on the outside of the house has been compromised. Your priority should be to locate and remedy these entry points. Physical control is the only option for beetles already in the home. You can vacuum them up, hand pick, etc. Dropping them in a bucket of soapy water will kill them, or you can just crush them. If the infestation is heavy enough, sticky traps may have some utility. 

Hi Kristen,

You are correct that the beetles can carry germs, but only the outside of their bodies. They are mechanical vectors, so the only way for them to introduce pathogens into your home is if they walk over a contaminant first, and then into your home. If there are no livestock nearby, the likelihood of them vectoring a potentially harmful pathogen is quite low. Keeping things clean is a good preventative measure, though. 

Darkling beetles are attracted to decaying organic matter, perhaps there is something in your home that is serving as a food source. I would check your stored food thoroughly for any beetles, especially dried foods (e.g. cereal, rice, flour, etc.). It's also possible that they are attacking/inhabiting wood that has started to rot. They can't destroy the wood on their own like termites, but if moisture has caused the wood to begin decaying, they can move in after. Inspect the wood in your home as well, including wooden furniture. I hope this helps with the infestation. Let me know if you have further questions.