Air quality
Air quality in Lahān today
Updated
Unhealthy for Sensitive Groups (US AQI 121) People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors. Model estimate for Mon, Oct 26, 6:45 am (01:00 UTC).
Live AQI, PM2.5, PM10 and ozone for Lahān, Madhesh, Nepal, with a 48-hour forecast and the best time to be outside.
- US AQI now
- 121 Unhealthy for Sensitive Groups
- PM2.5
- 50 µg/m³ 3.3× WHO 24-h guideline
- PM10
- 52 µg/m³
- Ozone
- 48 µg/m³
- Dominant pollutant
- PM2.5 sub-index 121
- Best hour today
- 11:45 am AQI 116
- European AQI
- 60
Air quality in Lahān right now
Right now the modelled US Air Quality Index for Lahān, Madhesh, Nepal is 121, which falls in the "Unhealthy for Sensitive Groups" band (up to 150). People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors.
The index is driven mainly by PM2.5, whose own sub-index is 121. Fine and coarse particles come from traffic, heating, industry, dust and smoke; they build up on calm nights and clear when wind or rain arrives.
PM2.5 is 50 µg/m³, 3.3 times the WHO 24-hour guideline of 15 µg/m³; PM10 is 52 µg/m³ against a guideline of 45; ozone is 48 µg/m³ (below the WHO 8-hour level of 100); nitrogen dioxide is 14 µg/m³ (below the 24-hour guideline of 25).
Also this hour: carbon monoxide 529 µg/m³.
Lahān AQI forecast: next 48 hours
Over the next 24 hours the AQI is forecast to range from 116 around Mon 11:45 am to 123 around Mon 11:45 pm, staying "Unhealthy for Sensitive Groups" throughout.
The following day looks similar, averaging about 123.
| Local time (Asia/Kathmandu) | US AQI | Category | PM2.5 µg/m³ | PM10 µg/m³ | Ozone µg/m³ |
|---|---|---|---|---|---|
| Mon 6:45 am | 121 | Unhealthy for Sensitive Groups | 49.8 | 52 | 48 |
| Mon 9:45 am | 117 | Unhealthy for Sensitive Groups | 18 | 19 | 142 |
| Mon 12:45 pm | 116 | Unhealthy for Sensitive Groups | 16.2 | 19 | 153 |
| Mon 3:45 pm | 116 | Unhealthy for Sensitive Groups | 19.6 | 23 | 145 |
| Mon 6:45 pm | 117 | Unhealthy for Sensitive Groups | 57 | 61 | 111 |
| Mon 9:45 pm | 121 | Unhealthy for Sensitive Groups | 79.4 | 85 | 85 |
| Tue 12:45 am | 123 | Unhealthy for Sensitive Groups | 67.1 | 72 | 54 |
| Tue 3:45 am | 122 | Unhealthy for Sensitive Groups | 47.3 | 50 | 21 |
| Tue 6:45 am | 121 | Unhealthy for Sensitive Groups | 46.2 | 48 | 45 |
| Tue 9:45 am | 122 | Unhealthy for Sensitive Groups | 22.9 | 27 | 133 |
| Tue 12:45 pm | 123 | Unhealthy for Sensitive Groups | 17.6 | 22 | 142 |
| Tue 3:45 pm | 123 | Unhealthy for Sensitive Groups | 21.1 | 24 | 133 |
| Tue 6:45 pm | 123 | Unhealthy for Sensitive Groups | 50.9 | 53 | 102 |
| Tue 9:45 pm | 122 | Unhealthy for Sensitive Groups | 84.5 | 89 | 70 |
| Wed 12:45 am | 124 | Unhealthy for Sensitive Groups | 77.1 | 82 | 38 |
| Wed 3:45 am | 127 | Unhealthy for Sensitive Groups | 55.3 | 59 | 13 |
| Wed 6:45 am | 129 | Unhealthy for Sensitive Groups | 50.1 | 53 | 33 |
Every third hour of the CAMS forecast via Open-Meteo. US AQI uses rolling averages (24 h for particles, 8 h for ozone), so it moves more slowly than the hourly concentrations.
Best time to be outside in Lahān today
Between 6 am and 9 pm local time, the cleanest air today is forecast around 11:45 am (AQI 116, Unhealthy for Sensitive Groups) and the worst around 6:45 am (AQI 121). The difference across the day is small, so timing matters little.
Lahān vs the rest of Nepal
Across 4 Nepal cities we track, the average US AQI right now is 84 (Moderate). Lahān at 121 is 37 points worse than average.
For context, the median across 3,556 cities worldwide is 58.
Air quality in cities near Lahān
| City | Distance | US AQI | Category | PM2.5 µg/m³ |
|---|---|---|---|---|
| Darbhanga | 86 km | 155 | Unhealthy | 102.4 |
| Muzaffarpur | 127 km | 162 | Unhealthy | 118.7 |
| Dhāka, Bihar | 131 km | 178 | Unhealthy | 156 |
| Pātan | 157 km | 91 | Moderate | 42.6 |
| Kathmandu | 158 km | 91 | Moderate | 42.6 |
| Bhāgalpur | 171 km | 132 | Unhealthy for Sensitive Groups | 76.4 |
| Patna | 184 km | 158 | Unhealthy | 105.9 |
| Siliguri | 193 km | 88 | Moderate | 26.3 |
Model vs measured
We found no measured PM2.5 sensor cell within 25 km of Lahān, so the numbers on this page are model estimates. Models capture regional pollution well but can miss very local sources such as a busy road or a nearby fire.
Wildfire smoke
PM2.5 is forecast to reach 81 µg/m³ in the next 24 hours while NASA satellites detected 32 fire hotspots within 300 km in the last day (nearest about 61 km away). Smoke is a likely contributor: keep windows closed, run an air purifier or HVAC filter, and check the fire map before heading out.
Advice for sensitive groups
At 121, children, older adults, pregnant people and anyone with asthma, COPD or heart disease should limit time outdoors, especially strenuous activity. A well-fitted N95/FFP2 mask cuts particle exposure; it does not filter ozone.
What the US AQI numbers mean
| US AQI | Category | What it means |
|---|---|---|
| 0-50 | Good | Air quality is satisfactory and poses little or no risk; a good time for outdoor activity. |
| 51-100 | Moderate | Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. |
| 101-150 | Unhealthy for Sensitive Groups | People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors. |
| 151-200 | Unhealthy | Everyone should reduce prolonged or heavy exertion outdoors; sensitive groups should avoid it and keep windows closed. |
| 201-300 | Very Unhealthy | Health alert: everyone should avoid prolonged or heavy exertion outdoors, and sensitive groups should stay indoors. |
| 301-500 | Hazardous | Emergency conditions: everyone should avoid all outdoor physical activity and stay indoors with filtered air if possible. The scale tops out at 500; heavier dust or smoke is shown as 500. |
Values on this page are modelled by CAMS (Copernicus) and served by Open-Meteo; they are estimates for the area around the city centre, not readings from an official monitor.
Nearby cities
More for Lahān
Air quality elsewhere
Data: Open-Meteo Air Quality API, Copernicus Atmosphere Monitoring Service (CAMS), NASA FIRMS.