SmogRank

PM2.5 now in a city: the latest hourly value, its 24-hour, 7-day, 30-day and year-to-date averages with its rank among all measured cities, the US EPA category, how it compares with the WHO guideline, and the "why it ranks here" notes (patterns in its own history and nearby fire, smoke and volcano evidence, named as likely causes, never confirmed), and the local hours its air was usually worst and cleanest over the last 30 days. Each measured city's trust says what stands behind it: checked (reference monitors at 2+ sites), one (a single reference site) or low (3+ low-cost sensors). Cities without a monitor get a model estimate, labelled as one, plus few_sensors when one or two low-cost sensors measure there (not ranked). No forecasts.

A measured city's daily mean PM2.5 (its local calendar days, µg/m³) and its daily rank, between two dates (up to 400 days; default the last 30), with monthly means. Also a city measured only in the past, or a day late (China's national network), with no rank.

Search SmogRank's cities by name (local, old and short names too: "München", "Bombay", "NYC"), or find the nearest ones to a point. Returns each city's path for the other tools, whether it is measured by ground monitors (ranked) or only estimated from a model, and its page; a name search also returns the countries and regions it names, as places with their page.

The ranking of measured cities by average PM2.5, worst first: a rolling window (24h, 7d, 30d, year to date) or a past period (a day 2026-09-30, a week 2026-W40, a month 2026-09, a year 2025). Optionally one country.