Using low-cost sensors to assess common air pollution sources across multiple residences

Area of Science:

• Environmental Science
• Public Health
• Sensor Technology

Background:

• Low-cost sensors enable advanced indoor air pollution monitoring.
• Understanding indoor particulate matter (PM) sources is crucial for public health.
• Existing ambient monitoring may not reflect indoor exposure levels.

Purpose of the Study:

• To investigate PM concentrations and sources in three urban households using calibrated sensors and Non-negative Matrix Factorisation (NMF).
• To compare indoor PM levels with outdoor concentrations and assess inter-household variability.
• To generate source profiles for understanding PM origins within and between homes.

Main Methods:

• Utilized calibrated particle matter (PM) sensors for PM2.5 and PM10 measurements.
• Applied Non-negative Matrix Factorisation (NMF) source apportionment to combined household data.
• Compared indoor PM concentrations with data from a nearby ambient monitoring site.

Main Results:

• Indoor PM concentrations were higher, more variable, and significantly different from ambient levels.
• One household exceeded World Health Organisation 24-h guideline limits for PM2.5.
• The indoor-to-outdoor (I/O) ratio varied, being lowest for PM1 (0.08) and highest for PM10 (4.93).

Conclusions:

• Indoor air pollution monitoring is essential for accurate exposure assessment, as indoor levels can exceed safe limits even in areas with good ambient air quality.
• The NMF methodology successfully modeled concentrations and provided insights into indoor PM source variability.
• Findings underscore the importance of in-home monitoring to protect public health from detrimental air quality.