Abstract

This study aims to evaluate a priority set of indoor environmental and air quality conditions in 22 social housing units as part of government programs for new housing construction and energy retrofit of existing housing. A comprehensive monitoring program was conducted in winter in two Chilean cities, Santiago and Coyhaique, including measurements of temperature, relative humidity, CO2, formaldehyde and fine particulate matter (PM2.5). The results showed a significant portion of the time outside the thermal comfort zone and excessive CO2 concentration and air humidity in the bedrooms, predominantly during the night hours. The decentralized ventilation system installed in most of the houses was unable to provide the required airflow rates, especially in the bedrooms. The formaldehyde concentration in the living rooms almost never exceeded the short-term exposure limit value of 100 µg/m3. The 24-h average indoor PM2.5 concentrations were above the WHO guideline of 15 µg/m3 for 77 % of the time in Santiago and 86 % in Coyhaique. Indoor PM2.5 concentrations were dominated by outdoor contributions. The chronic harm from exposure to the measured indoor formaldehyde and PM2.5 concentrations was estimated to be 1428 and 1982 DALYs/105 person/year in Santiago and Coyhaique, respectively. These values are twice to three times higher than those observed in California homes that comply with the standard ASHRAE 62.2. The results demonstrate the need for enhanced thermal standards in Chile and better ventilation solutions, capable of removing indoor pollutants and humidity generated indoors and reducing indoor PM2.5 concentrations particularly in highly polluted cities. © 2025