If you're curious, there's some reasonably priced ones on Amazon that might satisfy your curiosity (but are not safety rated or scientifically accurate).
If you're actually feeling anxious about this, there's a laundry list of things far more likely to harm you that you can act on right now, such as making sure you have sufficient smoke and CO alarms, a CO2 measurement tool to see if your popular rooms are getting enough fresh air, and a radon detector (though depending on region this may not apply).
