We launched Smart Air with a DIY air purifier, designed to provide low-cost, affordable clean air at a time when companies were charging $'000s for air purifiers.
When we built the original Blast and Blast Mini air purifiers, our priority was still costs but also the clean air delivery rate (CADR).
By the time the Blast and Blast Mini MkII was released, it was clear that the third focus of noise was equally important. Here's why...
In November 2021, GPS commissioned a National Teachers Survey of 750 US teachers with air purifiers in their class. The results are astounding:
- Nearly 70% of teachers turn off, or down, the HEPA filter due to noise.
- 40% teachers agree that noise from the HEPA filters make it harder to teach/harder to learn
- 31% teachers indicate that students ask for the in-room air filter to be turned off or down either daily (11%) or weekly (20%)
- 67% of teachers indicate they most often have the HEPA filter set to a level below High (including off). Most purifiers are spec'd to run on maximum setting
How would the Blast fare?
It's hard to overstate how critical noise is to the decision-making process. Few manufacturers prioritise low noise on the top setting, yet the marketing will focus how great the performance is at the highest levels.
But it's not just schools. Even in hospitals with signs such as "Do not turn down, this machine is providing you with clean air", purifiers are turned down or off.
What level of noise is acceptable in most workplaces?
The maximum decibels you should aim for is 50dBA but ideally 40dBA in a classroom. While this difference may not seem much, an increase of 10 dB means the purifier is “about” twice as loud for human ears or 10 times the power in electronic terms. In other words, an air purifier marked as 50 dB is double the loudness of a 40 dB air purifier!
How to work out the best purifier for your space
Work out the approximate volume of your room (length x width x height) and multiply this by the number of air changes per hour (ACH) you want in your space.
Let's assume you have a poorly ventilated 144m3 classroom providing just 1 ACH (natural ventilation) and you need 6 ACH
Your purifier needs to bring in 5 air changes an hour to meet your target
Multiplying 144 by 5 gives you a CADR of 720m3/h - this is how much clean air your air purifier(s) needs to provide
To make sure you size up the right purifier for your needs, work out how many purifiers can provide you with this CADR at a noise level of 40-45dBA.
Related links
Schools and universities
Smart Air in the workplace
5 reasons to choose Smart Air
