Lack of pro-active technology in indoor air quality protection

Indoor air quality (IAQ) influences the health of humans, the young and the old being generally more susceptible. Indoor air, the air that we breathe more than 80% of the time, is increasingly pre-treated or arriving through filters and ducts. Any technological solution for ventilation should pro-actively protect IAQ, by improving or not deteriorating the quality of outdoor air coming in, and alarming when IAQ levels are declining. In this study we examined how human IAQ needs are met, in design or in practice, by domestic ventilation systems, including natural ventilation, balanced ventilation, and adaptive systems. Methods Three population groups with different sensitivity towards air quality were recognized: healthy adults (between 20 and 49 years of age), healthy younger and older persons, and chronic lung sufferers. Risk aspects of ventilation systems were identified from literature: pollution accumulation, draught, and maintenance. Current indoor air quality in Dutch dwellings was evaluated from continuously measuring 4 indoor air quality indicators (CO2, humidity class, ventilation rate, and fine particles) in 37 dwellings for a whole week in winter each. Ventilation was by windows and grids, or grids and exhaust fans. Actual IAQ levels in dwellings were linked to complaint percentages in different air qualities derived from literature. Results The size of the groups with moderate (young, old) and high (lung sufferers) sensitivity is large and increasing, both in relative and absolute figures. An acceptable IAQ for the most susceptible group was not present in any of the dwellings, whilst only one dwelling met the standards for the group of young and older persons. Most common cause was inadequate ventilation. Newer systems with balanced ventilation have intrinsic risks with regard to maintenance (filters) and cleaning (ducts). Intelligent adaptive systems with mechanical exhaust only are in theory the best choice to protect IAQ. Discussion A healthy design of a ventilation system should include flexibility in supplied airflow (both a secure base level around the clock, and a high on-demand level) and an excellent removal of accumulated dirt on the surfaces of the ventilation system at the inlet side. Newer systems with adaptive features should be checked further in practice. Pro-actively protecting IAQ in dwellings through adaptive sensor-controlled ventilation systems may be a way to avoid health risks from indoor air for the elderly and other susceptible populations. Keywords: IAQ, ageing, health, ventilation, buildin