A Trial of Low-Cost Sensors to Observe Variations and Sources of Airborne Particle Levels in Homes in a Wood-Burning Community

摘要

Substantial exposure to air pollutants, even of outdoor origin, occurs within the home. Exposure may occur due to infiltration, direct exposure to indoor sources (including combustion and non-combustion sources), and from the faulty or unintended use or performance of heating appliances. However very little data exists describing the variation in exposure between homes and across populations, and the relative contributions of each source-impact pathway. A sensor package has been developed ("PACMAN") with the aim of characterising indoor concentrations of particulate matter and the contributing sources by using rapid direct-reading dust and gas sensors and analysing the temporal structure of the data collected to infer source activities. 10 PACMAN devices were deployed in private homes in the New Zealand town of Rangiora in late winter 2015 for a period of approximately one month as part of the "Community Observation Networks for Air" initiative. Data quality was variable with some sensors suffering from unexplained drift. Nevertheless, "emission events" were able to be extracted from the time series of most of the dust sensors. In most homes these events were not regular and were observed on an average of two events per week or less. In one home an average 19 emission events were detected per week. Events were classified on whether they were associated with a simultaneous increase in CO2 (presumed combustion sources). These events were found to decrease in frequency during the study whereas dust events not associated with CO2 remained consistently frequent. The provision of precise timing of these events has provided the basis of preliminary source identification. The high resolution data also provides substantial data on air mixing rates and relative exposures. Once these emission events were removed from the dataset, evidence of infiltration could be observed by comparison with outdoor PM10 and dust levels.