Carbon Dioxide Monitor

CO2 monitor tool

Borrow a Carbon Dioxide (CO2) Monitor Screening Tool Kit!


CO2 monitors are small, battery-powered devices that measure indoor air quality, help provide a general idea of how well a space is ventilated, and identify if you need to take steps to improve indoor air quality.

CO2 monitors can be borrowed for a three week loan period.

How do CO2 monitors work?
CO2 monitors measure the percentage of carbon dioxide in the air in a given space. They have a screen which displays the current CO2 percentage in “parts per million” or “ppm”. The screen also displays the relative humidity and temperature of the space they are measuring.

The CO2 reading in a given space will increase or decrease when:
• Ventilation increases or decreases (when HVAC systems are turned off or on, windows & doors are opened or closed, etc.)
• The number of people in the space increases or decreases
• CO2 emitting appliances like fireplaces are turned on or off

What CO2 levels are considered acceptable?
The device ‘s documentation outlines normal, average, and high CO2 levels as follows:
• 420 ppm Fresh outdoor air
• Below 1000 ppm Normal indoor CO2 level
• 1000 to 1400 ppm Average indoor CO2 level
• Above 1400 ppm High indoor CO2 level

Many factors contribute to CO2 readings, and high readings do not necessarily indicate a space is poorly ventilated. For example, a fireplace in an empty room can contribute significantly to the percentage of CO2 in a space, regardless of ventilation; as can a large group of people packed tightly into a well-ventilated room.

A carbon dioxide (CO2) monitor is a screening tool recommended for home and personal use and is not intended to be a substitute for professional air quality monitoring. Carbon dioxide (CO2) monitors are different from carbon monoxide (CO) monitors, which detect the presence of carbon monoxide gas to prevent carbon monoxide poisoning.

This loan program is offered thanks to funding provided by @NS Community Technology and the support of the Community Access to Ventilation Information (CAVI) initiative.

Where can I learn more about CO2 monitoring and how to use the monitors for screening purposes?

The CO2 monitors are intended for home and personal use and are not intended to replace professional air quality monitoring.