CO2 Monitor Lending Library

What is a tool lending library?

Lending libraries are a great way to share resources that are only needed for a short period of time -- not just books, but all sorts of things, including tools (e.g. chainsaws, sewing machines, scientific instruments).

Another advantage to maintaining a tool library is that often this allows groups to organize tool training, regular maintenance, and upgrading of the tools in the library. Saws can be kept sharp; sewing machines can be kept in working order; air monitors can be calibrated.

Why is CO2 Monitoring Useful?

CO2 monitoring has long been used for determining the effectiveness of indoor residential ventilation. Changes in indoor CO2 concentration can indicate whether air inside a room has 'refreshed' since its most recent occupants left, or whether there is sufficient space and/or ventilation inside a building that people are unlikely to spread airborne illness.

Indoor CO2 PPM and COVID-19 transmission. Recently, researchers have been exploring CO2 monitoring as factor in the assessment of the relative risk of indoor transmission of COVID-19. In the case of airborne illness, there are a few very common questions that CO2 monitoring can help answer:

By monitoring CO2 levels in a space over the course of a few days, it may be possible to determine patterns that can effectively inform daily practices without requiring futher ongoing CO2 monitoring. E.g., it may be determined that opening a single window in a room is enough to keep the indoor CO2 PPM at 'fresh air' levels even when fully occupied.

Starting your own CO2 Monitor Lending Library: Things to Consider

Some intial considerations when establishing a CO2 monitor lending library include:

Calibration. CO2 monitors range in price, features, and accuracy. For most use cases, it is important to make sure a CO2 monitor is calibrated in order to ensure that decisions are being made based on accurate CO2 readings. For this reason, we recommend initial and ongoing assessment of CO2 monitor calibration. Simple methods for determining CO2 sensor calibration are described here.

Baseline assessment and data recording. In many contexts, the relative CO2 PPM compared to an indoor space's 'baseline' CO2 reading is even more useful than the absolute CO2 PPM value. Determing baseline CO2 is most readily done by recording CO2 levels over time, which requires some sort of data storage -- either locally on the CO2 monitor itself, or via e.g. online data storage. Identifying or developing a reliable system for systematically recording CO2 levels -- ranging from paper and pencil, to Bluetooth (TM) devices, to web-based storage -- is therefore typically important.

Sensor placement and data interpretation. CO2 levels indoors are typically mostly impacted by human respiration, but may also be increased by additional sources of CO2, like propane stoves, and may be decreased by the presence of indoor plants. CO2 concentration in a room can vary spatially over time when point sources like humans are present, and can take a significant time to decrease after a room is emptied of occupants (depending on ventilation and other factors). CO2 monitoring devices can be impacted by severe changes in temperature or ambient pressure, as well as air gusts; some CO2 monitors have designs that attempt to compensate for these effects.