SmogRank / Episodes

Bad-air episodes

Episodes are found in each day's measurements; the list is being built from the history and appears here within the day.

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Each row: one bar per day, as tall as the number of cities counted that day and coloured by their median level; the number of cities; the highest daily reading and where. An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes.