Air Quality Lab — Njala, Sierra Leone
Air Quality Profile·
Njala reports an annual PM2.5 of 23.7 µg/m³. That's meaningfully above the WHO 2021 guideline of 5 µg/m³ yet within the EU annual limit of 25 µg/m³.
Njala
Sierra Leone
Sierra LeoneAnnual Average
ModerateWHO annual classification
23.7µg/m³
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
PM2.5
4242 µg/m³ — Unhealthy
4040 µg/m³ — Unhealthy
3737 µg/m³ — Unhealthy
3434 µg/m³ — Poor
1717 µg/m³ — Moderate
9.49.4 µg/m³ — Good
1111 µg/m³ — Fair
1212 µg/m³ — Fair
9.89.8 µg/m³ — Good
1616 µg/m³ — Moderate
2222 µg/m³ — Moderate
3434 µg/m³ — Poor
Jan
Feb
Mar
Apr
May
Jun
4242 µg/m³ — Unhealthy
4040 µg/m³ — Unhealthy
3737 µg/m³ — Unhealthy
3434 µg/m³ — Poor
1717 µg/m³ — Moderate
9.49.4 µg/m³ — Good
Jul
Aug
Sep
Oct
Nov
Dec
1111 µg/m³ — Fair
1212 µg/m³ — Fair
9.89.8 µg/m³ — Good
1616 µg/m³ — Moderate
2222 µg/m³ — Moderate
3434 µg/m³ — Poor
Best months: Jun–Jul, SepWorst months: Jan–Mar
Good5–10 µg/m³Fair10–15 µg/m³Moderate15–25 µg/m³Poor25–35 µg/m³Unhealthy35–50 µg/m³
Based on WUSTL PM2.5 dataset (2020–2024) · WHO 2021 thresholds
Confidence: ●●●
How air quality compares
Compared across Sierra Leone
Njala: 23.7 µg/m³. Typical range in Sierra Leone: 23.7–26.5 µg/m³. Low anchor: Bumpe, 23.3 µg/m³. High anchor: Freetown, 27.9 µg/m³.
12 cities tracked