Average PM2.5 by hour of day at my station — cleanest at midday, worst after dark
Hourly average PM2.5 across every day on record at my IQAir station, northern Johannesburg (local time). The midday dip is the sun stirring and dispersing the air; the after-dark climb is the evening inversion settling in plus domestic fires. What this means for timing outdoor exercise is a whole post later in the series. Source: my IQAir station · adhir.me