I am living in Northern Thailand that goes through the annual smoke season with often US AQI beyond 300 and in the Hazardous area. That experience lead to the f

I am living in Northern Thailand that goes through the annual smoke season with often US AQI beyond 300 and in the Hazardous area. That experience lead to the foundation of my startup AirGradient [1]. More and more people here are moving beyond air purifiers and install positive pressure systems in their house, offices or schools. Positive pressure systems take the outside air, run it through a set of high performance filters and pushes it inside the rooms. This has mainly two significant benefits: a) The positive pressure prevents dirty air from entering the room in the first place. As a results you become totally independent from the outside pollution and you can achieve zero PM2.5 inside even on the worst polluted days. I made a performance comparison between a standard air purifier and a positive pressure system and the positive pressure system won by a huge margin [2]. b) Low CO2. If you use normal air purifiers you are in a catch-22 situation. In order to get good results you need to keep your doors and windows closed. This leads to a very fast build up of CO2 in a room. High CO2 levels significantly impair cognitive performance and can lead to drowsiness and headaches. We measured the CO2 in classrooms [3] and very quickly you will see CO2 levels beyond 3000ppm (most Standards recommend levels below 1200-1500ppm). Against Covid transmission prevention, the best setup would probably be a combination of positive pressure system (to ensure a constant ventilation rate) together with a recirculation unit (standard purifier) inside the room to trap aerosols with viruses. We have open-source open-hardware build instructions for a DIY air quality sensor measuring PM2.5 and CO2 [4]. I am more than happy to send you some free PCBs (you just paypal me the cost of the postage) and you can build your own sensor and log the data. Contact me if you are interested. [1] https://www.airgradient.com/schools/ https://www.airgradient.com/schools/ [2] https://www.airgradient.com/blog/2020/03/30/air-purifier-vs-positive-pressure-fresh-air-system-an-unfair-battle/ https://www.airgradient.com/blog/2020/03/30/air-purifier-vs-... [3] https://www.airgradient.com/blog/2020/02/07/we-measured-the-co2-level-in-a-classrooms-this-is-what-we-found-out/ https://www.airgradient.com/blog/2020/02/07/we-measured-the-... [4] https://www.airgradient.com/diy/ https://www.airgradient.com/diy/