Fine Particulate Matter in Providence:
Siting, Calibration, and Analysis of the Breathe Providence Hyperlocal Air Monitoring Network
By Meg Fay
Breakdown of AQVI vulnerability criteria
Map of individual data layers: Socioeconomic Status (A), Household Characteristics (B), Racial and Ethnic Minority Status (C), and Adult Asthma Rates (D)
Meg implemented a two-step calibration process in which they first normalized sensors to a common “background,” then accounted for how humidity distorts sensor measurements. After applying these corrections to the data, Meg was able to achieve a level of accuracy comparable to that recommended by government guidelines. Lastly, Meg performed analysis of calibrated PM2.5 data across several monitoring sites during the winter of 2022-23, finding that the calibration successfully preserved sites’ unique pollution patterns.
Monitor Data Pre- and Post-Calibration
In this work, Meg describes their contributions to two aspects of Breathe Providence: the development of a GIS-based Air Quality Vulnerability Index (AQVI) and a field calibration method for particulate matter (PM2.5).
The objective of the Air Quality Vulnerability Index (AQVI) was to represent Providence neighborhoods in terms of vulnerability to the harmful effects of air pollution. The index is designed to reflect community priorities, such as those expressed in Providence’s Climate Justice Plan, in community advocacy campaigns, and through discussions with local environmental justice and health organizations.
Ultimately, the AQVI incorporated the spatial distributions of low-income populations, racial and ethnic minority populations, populations of children and the elderly, and areas of high asthma rates. See the image below for distributions of each of these populations across Providence independently, then integrated together into the index. Breathe Providence used the AQVI to guide and evaluate the monitoring site selection process and to identify priority areas for outreach and relationship-building.
Map of resulting AQVI in greater Providence area with Breathe Providence and RIDEM monitoring sites (as of February 2023)
The second piece of Meg’s work was developing a field calibration methodology for PM2.5. Low-cost sensors require calibration to ensure the accuracy and precision of the data, particularly for applications in scientific research and public policy.