Beijing · air and heat
Two records that moved in opposite directions. PM2.5 comes from the city's own monitoring stations and is judged here on both the US and the Chinese scale; the temperature comes from the thermometer at Capital Airport.
The city's annual mean PM2.5 against the standards that judge it. Which reference line matters depends on who is measuring — and by the strictest of them, the air is still a long way from clean.
Winter is the worst season and always has been: coal heating and cold, still air that traps what the city emits. The improvement is visible along every row, but it is steepest in the winter columns.
Air quality has a daily and a yearly rhythm, and neither is obvious from an annual average. Averaged over — — the city changed enough over the record that averaging all of it describes somewhere that no longer exists.
Every daily mean since December 2013, cut however you want to look at it: a year at a time, a month at a time, or the same month from several years drawn on top of each other.
The longest run of consecutive days or nights meeting each threshold, ranked across every year in the record. The window toggle applies here too.
Each calendar month's average temperature, ranked across every year. The arrows slide a four-month window through the calendar. A month only ranks once it is complete, so the running month appears separately, below the line.
Every metric on this page, one row per year. Click a column to sort by it.