DALY

Airborne contaminants cause significant harm to populations of people. People spend most of their time in their own homes and so their greatest exposure is likely to occur there. Existing standards that govern Acceptable Indoor Air Quality (IAQ) in residential buildings only consider a few contaminants. Exposure to them is limited using threshold mean concentrations over some period of time, but they do consider the harm they cause to populations of people.

This study presents a health-centered approach to quantify and compare the chronic harm caused by indoor air contaminants using disability-adjusted life-year (DALY). The aim is to understand the chronic harm caused by airborne contaminants in dwellings and identify the most harmful. Epidemiological and toxicological evidence of population morbidity and mortality is used to determine harm intensities, a metric of chronic harm per unit of contaminant concentration. Uncertainty is evaluated in the concentrations of 45 indoor air contaminants commonly found in dwellings.

This work quantifies the chronic harm caused by long-term exposure to common indoor air contaminants in dwellings located in the global north. Two methods are used to compute DALYs. The first uses incidence data and the second considers toxicological evidence. They are synthesised to produce Harm Intensities, the number of DALYs per person per unit of annual-average concentration the person is exposed to.

The protection from chronic harm provided by exposure limit values (ELVs) is evaluated for indoor air contaminants set by regulatory bodies of member countries in the Air Infiltration and Ventilation Centre (AIVC). Significant variability was found in the regulated harm levels from ELVs for the same contaminants across different countries, highlighting inconsistencies in public health protection. The concept of a regulated harm budget (RHB) is introduced, representing the total allowed harm from regulated contaminants implicitly set by a regulatory body.

Assessment methods to assess smart ventilation, in most countries focus only on comfort as criteria for the indoor air quality (IAQ), (Guyot et al., 2019). This is an issue as in doing so, pollutants that are known to cause harm to the human health are not taken into consideration while the exposure to VOCs will be elevated if the smart ventilation system lowers the ventilation flowrates to save energy (De Jonge and Laverge, 2021).

Buildings represent a major end use of energy throughout the world and are typically the dominant sector for electricity.   The use of that energy is to provide buildings services, the most important of which is Indoor Environmental Quality (IEQ).  Heating and air conditioning systems typically handle the thermal comfort aspects of IEQ; the energy impacts and economics of such systems is well studied.  The most important remaining aspect of IEQ is Indoor Air Quality (IAQ).