Heatmaps showing adjusted mean variations in terms of PM_2.5 between the 2019 and 2020 study periods by sensor and daily hour intervals.

<p>Each heatmap row represents graphically the adjusted mean variation in terms of PM_2.5 and PM₁₀ between 2019 and 2020 over the complete set of Purple Air sensors (All sensors) and by sensor (PA-S1 –PA-S23) over daily hours intervals defined. Shades of green are proportional to the estimated magnitude of the reduction in terms of PM_2.5 between 2019 and 2020; shades of red are proportional to the estimated magnitude of the increase in terms of PM_2.5 between 2019 and 2020 as showed by the colors legend on the right side of each plot. The “+” symbol denotes an increase in terms of pollutants concentration between year 2019 and 2020.</p>