"Lowest Light Pollution" bar chart is arranged in asecending order: smallest to largest (within the 10 cap) in light pollution.
Radiance is common metric to estimate light pollution. In Remote Sensing, radiance is the amount of light measured by the satellite sensor of a particular location. Radiance mean is taking multiple radiance measures for various locations in each city and estimating the average.
Note:
There does not seem to be a strong relationship between light pollution and various health metrics according to this data. However, we hope this visualization has taught you more about light pollution and its possible risks.