Borrow a Carbon Dioxide (CO2) monitor
You can use a CO2 Monitor to measure indoor air quality.
Knowing the CO2 levels can help you take steps to improve ventilation and lower the risk of airborne infections. Poor ventilation has been shown to cause symptoms such as tiredness and headaches.
To learn more, download our CO2 Monitoring for Indoor Air Quality Fact Sheet (PDF).
These devices are not carbon monoxide detectors and are not life safety devices.
How to borrow
You can borrow a CO2 monitor from a Digital Innovation Hub at select branches.
- A valid Toronto Public Library card is required (Adult and Teen cards only)
- Can be borrowed for seven days
- No holds or renewals
- Must return device to same Digital Innovation Hub where borrowed
- Replacement fee of $355 applies for lost or damaged kits
What's included
- An Aranet4 carbon dioxide monitor
- A quick start guide
- A CO2 Monitoring for Indoor Air Quality Fact Sheet (PDF)
How the monitors work
The Aranet4 CO2 monitor is a battery-powered CO2 device that is suitable for monitoring the CO2 level at home, at the office or in any other indoor environment.
Measurement data is displayed on a power-efficient e-ink screen.
| Indoor CO2 in parts per million | Ventilation performance, with respect to the number and activity level of people in the space |
| 600 or under | Excellent ventilation |
| 601 to 800 | Good ventilation |
| 801 to 1000 | Fair ventilation |
| 1001 to 5000 | Poor ventilation |
To learn more, download the Aranet4 carbon dioxide monitor user manual (PDF).
Tips for accurate readings
- Take the device outdoors in an open area away from crowds. After a few minutes, the reading should be between 400 to 450 ppm. This means it is properly calibrated. If it is not properly calibrated, follow the instructions in the user manual (PDF).
- Always take readings at least two metres away from people's faces or your readings may be artificially high.
- Readings should be performed when the space is occupied. If you expect 30 people in the room, you'll want to take a reading with 30 people present.
- You may notice the readings stay steady, rise continuously or cycle from higher to lower values. These patterns provide hints to how the space is ventilated and may guide your troubleshooting to improve ventilation in the space.
- Optional: You can download the free Aranet4 app from the Mac App Store or Google Play Store to track your CO2 measurement data.
Resources and further reading
- City of Toronto: COVID-19 & Respiratory Viruses: Reduce Virus Spread Guide
- Health Canada: Carbon dioxide in your home
- Health Canada: COVID-19: Guidance on indoor ventilation during the pandemic
- Health Canada: Improve indoor air quality in your home
- Health Canada: Ventilation and the indoor environment
- Canadian Centre for Occupational Health and Safety: Indoor Ventilation: Guidance During the COVID-19 Pandemic
Accessibility accommodations
If you identify as a person with a disability and require an accessibility accommodation to borrow this device, please contact dihlending@tpl.ca or call Answerline at 416-397-5981 to make a request as far in advance as possible.