Technology

The Pillars of Indoor Air Hygiene

• Ventilation at its most basic leveldescribes mechanical systems that draw outdoor air into buildings. Some of these systems are capable of heating and cooling the air. Advanced ventilation systems can also perform dehumidification. 
  
  A Dedicated Outdoor Air System (DOAS) is part of an advanced HVAC system and fully conditions outside air through cooling, heating, and dehumidifying. 
  
  Natural ventilation via opening windows and doors is possible, but generally not preferred for logistics and security reasons, it can also be challenging in some climates. 
  

• Filtration captures particles and captures, but does not necessarily kill, pathogens. Filtration describes the replaceable media inside HVAC equipment that removes particulate contaminants, either from outside air or from recirculated indoor air. 
  
  Filters come in a range of efficiencies. The higher the efficiency, the more the media captures. Higher efficiency filters demand higher energy consumption because the air blower must develop higher pressure to push air through the media. Efficiency is measured as a MERV rating. To remove significant IAQ dangers, MERV 13 or higher should be used. If possible, MERV 17 (or HEPA) filters should be used to most thoroughly address PM2.5 and microbes. 

• Purification captures vapors (VOCs) and captures and kills  (or inactivates) pathogens. Purification is often a layered system to address both pollutant removal and its internal build-up. For example, HEPA filtration can also include UV-C light to hinder microbial growth on equipment surfaces. In addition, VOCs can be removed using special filters with chemical or molecular filtration capabilities.
  
  Surfaces exposed to excess humidity are major sources of airborne pathogens as moisture encourages mold and bacterial growth. Microbial growth generates spores, allergens, and VOCs. Because of that, supplemental dehumidification is essential to the optimal functioning of air purification systems wherever humidity is involved.