Fig. 6: Distributions of the annual duration of communities exceeding high ultrafine particle (UFP) exposure levels recommended by the World Health Organization Air Quality Guidelines (WHO AQG).
From: Machine learning-enhanced high-resolution exposure assessment of ultrafine particles
a Distribution of the annual cumulative hours at the community level exceeding the hourly high exposure level (2 × 104 particles‧cm−3). b Distribution of the annual cumulative days at the community level exceeding the 24-h mean high exposure level (104 particles‧cm−3). c Correlation between the annual durations of high UFP exposure respectively identified based on the 24-h mean and 1-h levels suggested by the WHO AQG. The size and color of the dots represent the population of each community, while the bars indicate the population experiencing various annual durations of high exposure. The populations without any high UFP exposure are not shown in the figure; these are 1.20 million based on the 24-h mean level and 2.87 million based on the hourly level.
