What Should You Monitor in Your Home? CO, CO₂, Radon & Indoor Air Quality Explained

Indoor air can contain different gases and pollutants, and no single detector measures everything. Carbon monoxide (CO) detectors help protect against a dangerous combustion gas, CO₂ monitors provide information about indoor carbon dioxide levels, and radon monitors measure a naturally occurring radioactive gas. Indoor air quality monitors may also measure pollutants such as particulate matter and volatile organic compounds (VOCs).

Understanding what each device measures is the first step toward choosing the right monitoring solution for your home, basement, camping trip or RV.

1. Carbon Monoxide (CO): A Critical Home Safety Concern

Carbon monoxide is a colorless, odorless gas produced by incomplete combustion. Common sources include fuel-burning furnaces, water heaters, fireplaces, generators and vehicle exhaust.

Because you cannot reliably detect CO with your senses, a dedicated carbon monoxide alarm is an important part of household safety.

What does a CO detector do?

A carbon monoxide detector monitors CO concentration and activates an alarm according to its design and applicable safety requirements.

When choosing a CO detector, consider:

• Whether it meets the applicable safety requirements for your market.

• Its audible and visual alarm functions.

• Power supply and backup options.

• Sensor service life and device replacement instructions.

• Whether its display, connectivity and other features match your needs.

Some models display CO readings, while others primarily provide an alarm. A digital display can provide additional information, but it does not replace an alarm designed and certified for CO safety.

For more information, see the CDC's Carbon Monoxide Poisoning Basics.

2. Carbon Dioxide (CO₂): Understanding Indoor Air and Ventilation

Carbon dioxide is different from carbon monoxide. People naturally exhale CO₂, and concentrations often increase in occupied rooms when ventilation is insufficient for the number of people present.

A CO₂ monitor can help you observe changes in indoor CO₂ levels and understand when ventilation may need attention.

What does a CO₂ monitor measure?

A CO₂ monitor measures carbon dioxide concentration, commonly expressed in parts per million (ppm).

Depending on the device, it may also measure temperature and humidity or provide app connectivity and historical data.

CO₂ monitoring is useful in bedrooms, living rooms, offices, classrooms and other occupied spaces. It can also provide environmental information in RVs and other enclosed living areas.

However, CO₂ is only one indicator of indoor conditions. A CO₂ reading does not tell you whether carbon monoxide, radon, formaldehyde or particulate matter is present.

Important: A CO₂ monitor cannot replace a dedicated carbon monoxide alarm.

3. Radon: A Hidden Indoor Environmental Risk

Radon is a naturally occurring radioactive gas released from the ground. It can enter buildings through openings in foundations, construction joints and gaps around service pipes.

Because radon cannot be detected by sight or smell, testing is needed to understand its concentration indoors.

Why use a radon monitor?

Radon levels can vary over time. A radon monitor can help users observe readings and trends, depending on the device's measurement method and features.

When selecting a radon detector, consider:

• Whether it supports short-term readings, long-term averages or both.

• How quickly the device provides useful results.

• Whether it records historical measurements.

• Whether it supports app connectivity.

• Its stated accuracy, operating conditions and calibration requirements.

A single reading may not fully represent long-term radon exposure. Follow recognized testing guidance and the device manufacturer's instructions when interpreting results.

For additional information, see the U.S. Environmental Protection Agency's indoor air quality resources.

4. What About PM2.5, PM10, VOCs and Formaldehyde?

Indoor air quality includes more than gases. Depending on the building, activities and materials present, indoor air may contain particles and chemical pollutants.

PM2.5 and PM10

Particulate matter consists of small airborne particles. PM2.5 refers to fine particles, while PM10 includes a broader size range.

A particulate monitor can help users observe changes in particle concentration associated with activities such as cooking, dust disturbance and smoke entering the indoor environment.

VOCs and Formaldehyde

Volatile organic compounds (VOCs) are a broad group of airborne chemicals that may come from paints, cleaning products, building materials, furnishings and other sources.

Formaldehyde is one specific chemical that can contribute to indoor air pollution.

A VOC monitor and a formaldehyde detector are not necessarily interchangeable. Different devices may use different sensing methods and measure different target substances.

When evaluating an indoor air quality monitor, check exactly which pollutants it measures instead of assuming that one device detects every possible contaminant.

The EPA provides additional information in its guide to volatile organic compounds and indoor air quality.

5. CO Detector vs. CO₂ Monitor vs. Radon Detector

Device	What it measures	Main purpose	Typical applications
CO detector	Carbon monoxide	Safety monitoring and alarm	Homes, fuel-burning appliance areas, suitable RV applications
CO₂ monitor	Carbon dioxide	Indoor environmental and ventilation awareness	Bedrooms, offices, classrooms, RVs
Radon detector	Radon concentration	Radon monitoring over time	Homes, basements and other indoor spaces
Indoor air quality monitor	One or more specified pollutants and environmental parameters	Observe selected indoor air conditions	Homes, offices and other indoor environments
Combination gas detector	The specific gases and parameters supported by the model	Monitor multiple specified hazards or conditions	Applications defined by the product's capabilities

The key distinction is the target substance. A device designed for one gas should not be assumed to detect another gas unless the manufacturer explicitly specifies that capability.

6. What Should You Monitor at Home, While Camping or in an RV?

Different environments have different monitoring needs.

At Home

A dedicated CO alarm is important where fuel-burning equipment may create a carbon monoxide hazard.

Depending on your home and concerns, you may also consider CO₂ monitoring for ventilation awareness, radon monitoring for long-term environmental assessment, or an indoor air quality monitor for selected pollutants.

Basements, bedrooms, kitchens and living rooms can have different sources of environmental concerns. Choose devices according to the risks and measurements relevant to each space.

While Camping

Camping equipment can create carbon monoxide hazards if fuel-burning devices are used incorrectly.

Never use generators, charcoal grills or camp stoves inside tents or other enclosed spaces. Follow the equipment manufacturer's safety instructions and use appropriate CO alarms where recommended.

Portable environmental monitors can provide additional information about specified gases and conditions, but they do not make unsafe combustion practices safe.

In an RV

An RV combines cooking, sleeping and living areas within a relatively compact space. Depending on its appliances and configuration, monitoring needs may include carbon monoxide safety and additional environmental measurements.

A dedicated CO alarm should remain a priority. A portable CO₂ monitor can provide separate information about carbon dioxide levels, temperature and humidity if those functions are supported.

Before selecting a device, confirm that it is suitable for the intended environment and follow the RV and detector manufacturers' installation instructions.

7. How to Choose the Right Monitoring Solution

Before purchasing a detector or monitor, ask four questions:

1. What do I need to measure?

Identify the specific gas or pollutant. CO, CO₂, radon and particulate matter require different measurement capabilities.

2. Do I need an alarm or monitoring data?

A safety alarm is designed to warn of a specified hazard. A monitor may focus on measurements, trends and environmental awareness. Some products combine these functions, but their capabilities must be verified.

3. Where will I use it?

Consider whether the device is intended for a home, basement, office, camping trip, RV or professional application.

4. What features matter to me?

Depending on the application, useful features may include a clear display, historical data, app connectivity, rechargeable power, temperature and humidity readings, or audible and visual alerts.

Do not choose a detector based only on its number of functions. The most important factor is whether it measures the substances you actually need to monitor.

8. Explore FABISENSE Gas Detection and Environmental Monitoring Solutions

FABISENSE develops products for home safety, environmental monitoring, camping, RV applications and other suitable uses.

PTH-252 Series: Multi-Function Plug-In Detection

The FABISENSE PTH-252 Series offers different product configurations for specified combinations of CO, combustible gas and smoke detection.

Choose the model according to its actual detection functions and intended application.

Explore the FABISENSE PTH-252 Series.

PTH-282B+: Smart CO & CO₂ Monitoring

The FABISENSE PTH-282B+ combines carbon monoxide and carbon dioxide monitoring with Bluetooth app connectivity, historical data tracking, temperature and humidity monitoring.

It is designed for users who want to observe both CO and CO₂ readings in one portable device.

Explore the FABISENSE PTH-282B+.

Radon Monitoring Solutions

FABISENSE also offers dedicated radon monitoring models. Depending on the model, features may include continuous monitoring, data logging or connectivity.

Explore the FABISENSE PTH-252RW.

Review each product's specifications and user manual to confirm the exact measurement functions, operating conditions and applicable certifications.

Frequently Asked Questions

What is the difference between a CO detector and a CO₂ monitor?

A CO detector monitors carbon monoxide for safety purposes, while a CO₂ monitor measures carbon dioxide, often to help users understand indoor environmental conditions and ventilation. They are not interchangeable.

Do I need an indoor air quality monitor if I already have a CO alarm?

They serve different purposes. A CO alarm addresses a specific safety hazard. An indoor air quality monitor may measure selected pollutants or environmental parameters, depending on its sensors.

Does a CO₂ monitor detect radon or formaldehyde?

Not unless the device is specifically designed to measure those substances. Always check the product's stated detection capabilities.

Is a multi-function detector suitable for every room?

Not necessarily. Suitability depends on the gases measured, the device's intended application, installation requirements and local safety guidance.

How can I improve indoor air quality?

Start by identifying and reducing pollution sources, improving ventilation where appropriate, and using suitable filtration as a supplement when needed. Monitoring can help you understand selected environmental conditions, but it does not replace source control or proper ventilation.

Final Thoughts

A safer and more informed indoor environment starts with understanding what each detector measures.

CO alarms address carbon monoxide safety. CO₂ monitors provide information about carbon dioxide levels. Radon monitors help users understand radon concentrations over time, while indoor air quality monitors can measure selected particles, chemicals and environmental parameters.

Choose products based on the specific risks, measurements and conditions that matter to your home or intended application.

FABISENSE — Smarter Sensing. Safer Living.