Japan · The summary is refreshed every 15 minutes.
November 12
The air is clean now
Measured 05:00
Nagano
6°C
Clear
1029
hPaAtmospheric
pressure
87%
Humidity
Nagano, November 10, 2026: daily mean PM2.5 2 µg/m³ (5 sensors), level “Low” — as in the Atmy Data Hub. Now (07:00 local time): 4.2 µg/m³. Open methodology and data in JSON: Methodology and data sources · JSON
Right now in Nagano, PM2.5 averages 4.2 µg/m³ — “good” on the US EPA scale (approximate, from hourly readings). Mean of 5 sensors from Government stations, readings from 05:00–05:00 local time (20:00–20:00 UTC), summary prepared at 07:00 local time. Median: 5.0 µg/m³; range across sensors: 2.0–6.0 µg/m³.
In Nagano the air is good 🟢 AQI 23. About the same as three hours ago. ☀️ +6 °C · No precipitation · Wind 1 m/s
In Nagano the air is good right now (approximate, US EPA scale). From 18:00 to 07:00 local time the city mean PM2.5 rose from 3.2 to 4.2 µg/m³.
Light wind (1 m/s) in the evening or at night, as the air cools, possibly traps particles near the ground (a temperature inversion). High humidity (87%) possibly makes optical sensors read somewhat higher.
Weather now: clear, 6°C, wind 1 m/s, humidity 87%. No major change in the wind is expected in the coming hours. By 18:00 the temperature will be about 13°C.
Written automatically at 07:00 local time (22:00 UTC) from sensor measurements and the weather forecast. Values are approximate; hypotheses are marked.
1 m/s
Wind, WSW
0 mm
Precipitation today
2 µg/m³ Low
Daily mean PM2.5 on November 10, 2026 (00:00–24:00 UTC = 09:00–09:00 UTC+9): 2 µg/m³ from 5 sensors that passed the quality check — the same value as in the Atmy Data Hub.
45/100Moderate · An estimate of weather conditions · not a PM2.5 forecast
17°/6°
Index by time of day
62/100Moderate
Night
Morning
Day
Evening19°/8°
Index by time of day
55/100Moderate
NightMorningDayEvening18°/8°
Index by time of day
60/100Moderate
NightMorningDayEvening16°/10°
Index by time of day
54/100Moderate
NightMorningDayEvening14°/8°
Index by time of day
47/100Moderate
NightMorningDayEvening17°/5°
Index by time of day
57/100Moderate
NightMorningDayEveningForecast of conditions that trap pollution near the surface
6°
Clear. Feels like 3°C
10°C69%17°C47%11°C75%1m/sWind from the WSW
4m/sWind gusts
Wind force: 1
Light wind is expected over the next few hours.
Japan
17°C6°C
19°C8°C18°C8°C
16°C10°C
14°C8°C17°C5°C18°C10°C12°C3°C9°C2°C15°C2°C
Highest current reading: 6.0 µg/m³ (小島田 (環境省 大気汚染物質広域監視システム（そらまめくん） — 長野市)). Lowest: 2.0 µg/m³ (篠ノ井 (環境省 大気汚染物質広域監視システム（そらまめくん） — 長野市)). The list shows every sensor, highest first.
Source: atmy.ai monitoring network
Sensors in the summary by network: Government stations — 5 sensors.
Atmy shows the networks’ readings after the Data Hub’s quality check: test devices and sensors that fail it are left out.
921
TokyoJapan
49NagoyaJapan
18KobeJapan
16Cities with the most sensors
All sensors on the map, by city as the map assigns them; the city’s values count only the sensors that pass the Data Hub’s quality check.
Daily mean PM2.5 of the city sensors, µg/m³
Click a day to see its date and value.
An Atmy card with the air quality in Nagano now: it is refreshed every 15 minutes and links to this page. Paste the code into your site.
Japan · City ranking · All pilot cities
Daily mean PM2.5 on November 10, 2026 (00:00–24:00 UTC = 09:00–09:00 UTC+9): 2 µg/m³ from 5 sensors that passed the quality check — the same value as in the Atmy Data Hub. No. 43 of 43 cities in Japan and No. 673 of 676 worldwide, from the most polluted.
Right now in Nagano, PM2.5 averages 4.2 µg/m³ — “good” on the US EPA scale (approximate, from hourly readings). Mean of 5 sensors from Government stations, readings from 05:00–05:00 local time (20:00–20:00 UTC), summary prepared at 07:00 local time. Median: 5.0 µg/m³; range across sensors: 2.0–6.0 µg/m³.
The current level is “good” (US EPA scale, approximate). Air quality is satisfactory; no restrictions are recommended. This is the standard guidance of the scale, not medical advice.
Highest current reading: 6.0 µg/m³ (小島田 (環境省 大気汚染物質広域監視システム（そらまめくん） — 長野市)). Lowest: 2.0 µg/m³ (篠ノ井 (環境省 大気汚染物質広域監視システム（そらまめくん） — 長野市)). The list shows every sensor, highest first.
From Atmy sensors and connected public networks (citizen, experimental and government monitors), aggregated by Atmy. Values are approximate; see the methodology.
The summary is rebuilt every 15 minutes from the latest reading of each sensor, each no older than one hour.
The daily value is the Data Hub’s: the mean of the city’s sensors that passed the nightly quality check, each with at least 12 valid hours, and only with sensors at four places 500 m apart; days are UTC.
“Now” uses the same sensors and rule: the mean of their latest readings, each at most 60 minutes old, shown only with sensors at four places 500 m apart reporting.
Source: public Atmy monitoring data. Methodology and data sources · Data terms
