CO2 is a widely used indicator of room occupancy and the need to ventilate, which according to Elta Fans has proved useful in encouraging more engagement with improving IAQ. However, as structures become increasingly energy efficient and airtight, there is a danger that other types of outdoor air pollution will become trapped in these spaces.
There is the risk that if these are not monitored, they will build up to unsafe levels, ultimately undermining the journey towards healthier indoor air. A more sophisticated approach is therefore required to move beyond merely measuring CO2, and take into account a wider array of pollutants.
Ana Cross, AHU product manager at Elta Fans, commented: “One of the defining features of the past 18 months has been a renewed focus on IAQ and how we can improve the health of our buildings. CO2 has served as a useful proxy to measure progress in this, but we now need to work towards a more sophisticated approach.
“Other pollutants can come from a range of sources – everything from general traffic, industrial, commercial, agricultural, and domestic activities. As structures become better insulated, we have to ensure that our ventilation systems are equipped to meet this challenge. One cannot mitigate against the invisible, which is where more advanced monitoring becomes key.”
Some of the most health-critical pollutants to address are particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), and total volatile organic compounds (TVOCs). Given the main source of some of these, natural ventilation such as opening a window can actually have adverse effects in certain locations e.g., city centres. In these circumstances, mechanical ventilation offers the most protection for building occupants.
Alongside pollutants, there is also the issue of relative humidity (RH). Humidity levels in indoor spaces play an important role, from supporting good human health and wellbeing, to helping preserve stored food, electronic equipment, artwork etc. Too high humidity levels can cause damp and condensation problems, and at the opposite end of the scale, too low levels of humidity can lead to a dryness of the skin, eyes, nose and throat.
This is crucial, as the human body's first line of defence against airborne agents (both chemical and biological) is the mucosa lining at the top airways (nose and throat), and if this dries out, the body's immune response becomes compromised. Thus, achieving healthy levels of humidity within an occupied space is an important step towards delivering optimum levels of IAQ for good health and wellbeing.
Ms Cross concluded: “We have seen some positive steps in the right direction over the past 18 months, as awareness surrounding the effects of IAQ increases. However, we need to ensure that this progress continues, and that we start to adopt a more sophisticated approach to monitoring the air inside our buildings.”