For High PM2.5, an Air-Filtering System Isn’t Enough
Created By RISC | 10 months ago
Last modified date : 10 months ago
Did you know that staying indoors when air pollution is high doesn’t protect you?
Our homes or workplaces can’t completely shield us from PM2.5 or smaller particles. These particles are small enough to pass through closed doorways or windows. Air purifiers can, to some extent, capture PM2.5. But the particles can continue to enter the building through various openings.
So how do we deal with this problem?
One way is to increase the air pressure inside the building to create a positive pressure environment. Higher air pressure will push out air containing PM2.5 and other particles.
A positive pressure system can be used with an outside intake and an air filter capable of filtering small particles (HEPA H13 Filter). The following conditions are need for a positive pressure air condition:
• Supply air: With minimum ventilation rates and standards. Residential buildings, for example, require an air change rate of 0.35-1 ACH (but not less than 15 cfm/person), with bedrooms recommended at 2-4 ACH and living rooms recommended at 3-6 ACH in case of co-infection prevention.
• Exhaust air: The exhaust air volume must be 10-15% less than the supply air volume.
• The difference in air pressure inside and outside the building must be greater than 2.5 Pa (a difference of 8 Pa is considered completely positive air pressure that can protect against particles).
Aerating and maintaining positive pressure in buildings will have no effect on us. It also aids in the reduction of carbon dioxide produced by breathing in the room.
We may not be able to avoid the particle season today. Our home is our last line of defense. If the ventilation system is properly designed, it will allow us to stay in the house safely. If you go outside, remember to wear a mask to protect yourself from PM2.5.
Story by: Napol Kieatkongmanee, Senior Sustainable Designer and TREES-A, Building Technology, Intelligent Systems, Innovative Solutions Specialist, RISC
References:
https://acat.or.th/download/acat_or_th/V26-(2).pdf
https://commercialairfiltration.co.uk/blogs/news/positive-and-negative-pressure-rooms#:~:text=Air%20pressure%20in%20the%20room,ideally%20should%20be%208%20Pa.
https://www.tmn.co.th/download/tmn_co_th/CL_Cooling_Load_Calc/Calculations-of-Ventilation-Rate-According-to-ASHRAE-Standard-62-1.pdf