Investigation of indoor air quality in coal-heating rural residential buildings in Northern China based on longtime monitoring

Indoor air quality (IAQ) is closely related to resident health and has been drawing extensive consideration from academics as well as government regulators. However, few studies have quantitatively investigated IAQ in rural buildings during the heating period, in which the resident time indoors is relatively longer. This study has monitored and quantitatively analyzed the indoor air parameters (temperature, CO2, formaldehyde and PM2.5) of 20 rural houses in Northern China during the heating season (15 days out of 120). After quantitatively analyzing the IAQ parameters, the Pearson correlation model was also adopted to evaluate the relationships between them. Results showed that only 4 households could keep the indoor temperature above 18°C for more than 50% of the heating period. Additionally, there were 7, 2 and 18 households, of which the over-standard time of CO2, formaldehyde and PM2.5 took up more than 40%. The concentration of indoor PM2.5 was higher than outdoors most of the time. Therefore, indoor PM2.5 was mainly caused by indoor activities rather than transported from outside. Correlation analysis showed that CO2 was positively correlated with formaldehyde and PM2.5 in 16 and 12 households.