310 measured days · judged by daily PM2.5 against the WHO guideline and SA law
Daily-average PM2.5 at my IQAir station, northern Johannesburg, Jul 2025–Jun 2026 (310 days with data). Bands: clean (≤5 µg/m³), over the WHO annual guideline (5–15), over the WHO 24-hour guideline (15–40), and over South Africa's legal daily limit (>40). The takeaway: half the year breached the WHO daily guideline, yet only 5 days were actually illegal — the gap between "healthy" and "legal." · adhir.me