The threats in shelter air are invisible: you cannot see rising CO2, smell carbon monoxide, or detect fine particulates until they have already affected you. A handful of inexpensive sensors turn all of those into a number on a screen. This is the highest-value, lowest-cost upgrade in the entire air category.
The three you actually need
- Carbon monoxide (CO) — produced by any combustion (generator, heater, stove). CO is acutely lethal, so a Kidde Carbon Monoxide Detector is non-negotiable anywhere you burn fuel.
- Carbon dioxide (CO2) — the buildup from breathing in a sealed space. An Aranet4 CO2 Monitor shows you when to increase ventilation before symptoms start.
- Particulates (PM2.5) — smoke, dust, and fallout particles. A Temtop Air Quality Monitor handheld monitor reads the fine-particle load so you know when filtration needs to ramp up.
What to look for
- The right target. CO and CO2 are different gases needing different sensors — do not assume one device covers both.
- Battery and backup power. Your monitors must keep running when the grid does not. Favor long battery life or low-draw USB devices.
- Audible alarms. A silent readout you are not watching at 3 a.m. saves no one. Alarms matter.
- Sensor lifespan. Electrochemical sensors age out (often 5–10 years). Note replacement dates.
Place them well
Put CO detectors near sleeping areas and any combustion source. Put the CO2 monitor in the main occupied space at head height. Keep the particulate monitor near your air intake so you can see what is coming in.
Turn readings into action
Sensors only help if you respond. Rising CO2 means increase ventilation. Any CO alarm means shut down combustion and ventilate immediately. Climbing particulates mean seal up and switch to HEPA or NBC filtration. Cheap sensors, paired with a plan, are what keep the invisible from becoming fatal.