Did Purple-Air Sensors Agree with EPA Regulatory Air Quality Monitors in North Carolina During the Canadian Wildfire Smoke Episode in the Summer of 2023?

Jackson Coley

jcoley1@unca.edu

ATMOSPHERIC SCIENCES

Particulate matter with a diameter between 1.0–2.5 µm (PM2.5) is an atmospheric pollutant that primarily forms as a product of combustion. Because of the risk to human health, the EPA regulates PM2.5 using Air Quality Monitoring Stations (AQMS). Due to extreme cost, AQMS are only located in regions of large population. However, low-cost sensors, such as the Purple-Air PA-II, have been developed to provide PM2.5 data in less dense regions of population. Previous studies have shown that under low-pollution levels (<25 µg m-3), the PA-II unit is accurate when compared to the EPA AQMS. In contrast, under moderate to high pollution levels (>25 µg m-3) and under high relative humidity, the PA-II overestimates PM2.5 concentration. In summer 2023, wildfires raged across northern Canada, leading to thick smoke protruding into the southeastern United States. North Carolina was affected by this smoke as there were several days where reported PM2.5 concentrations exceeded the EPA daily mean limit of 35 µg m-3. This work will examine the performance of the PA-II unit compared to EPA AQMS in North Carolina in June and July 2023, providing the opportunity to identify the effects of wildfire smoke on the PA-II unit in a region known to have high relative humidity in the summer months. Insight provided from this study will help inform residents of North Carolina on the integrity of the PA-II data.

May-14-2024