Czechia · The summary is refreshed every 15 minutes.
October 22
The air is moderate now
Ostrava
10°C
Cloudy
52AQI
1019hPa
Atmospheric
pressure
84%
Humidity
Ostrava, October 21, 2026: daily mean PM2.5 14 µg/m³ (8 sensors), level “Moderate” — as in the Atmy Data Hub. Now (20:00 local time): 9.4 µg/m³. Open methodology and data in JSON: Methodology and data sources · JSON
Right now in Ostrava, PM2.5 averages 9.4 µg/m³ — “moderate” on the US EPA scale (approximate, from hourly readings). Mean of 8 sensors on the Atmy network, readings from 19:52–19:57 local time (17:52–17:57 UTC), summary prepared at 20:00 local time. Median: 8.5 µg/m³; range across sensors: 3.1–17.4 µg/m³.
In Ostrava the air is moderate right now (approximate, US EPA scale). From 07:00 to 20:00 local time the city mean PM2.5 stayed roughly level: from 8.9 to 9.4 µg/m³. The highest hour was 12:00 with 16.9 µg/m³.
Light wind (0 m/s) in the evening or at night, as the air cools, possibly traps particles near the ground (a temperature inversion).
Weather now: cloudy, 10°C, wind 0 m/s, humidity 84%. No major change in the wind is expected in the coming hours. By 07:00 the temperature will be about 5°C.
Written automatically at 20:00 local time (18:00 UTC) from sensor measurements and the weather forecast. Values are approximate; hypotheses are marked.
0 km/h
Wind, SW
14.3 mm
Precipitation today
14 µg/m³ Moderate
Daily mean PM2.5 on October 21, 2026 (00:00–24:00 UTC): 14 µg/m³ from 8 sensors that passed the quality check — the same value as in the Atmy Data Hub.
Monthly means of quality-checked sensors, as in the Data Hub trend; the current month is still incomplete, “-” means no data.
26%An estimate of weather conditions · not a PM2.5 forecast
13°/7°
Index by time of day
40/100Moderate
Night
Morning
Day
Evening15°/5°
Index by time of day
56/100Moderate
NightMorningDayEvening12°/6°
Index by time of day
44/100Moderate
NightMorningDayEvening12°/3°
Index by time of day
57/100Moderate
NightMorningDayEvening12°/5°
Index by time of day
43/100Moderate
NightMorningDayEvening13°/3°
Index by time of day
54/100Moderate
NightMorningDayEveningForecast of conditions that trap pollution near the surface
10°
Cloudy. Feels like 10°C
10°C88%11°C74%
9°C86%0km/hWind from the SW
7km/hWind gusts
Wind force: 0
Light wind is expected over the next few hours.
Czechia
13°C7°C15°C5°C12°C6°C12°C3°C12°C5°C13°C3°C13°C5°C11°C8°C11°C7°C10°C6°C
Highest current reading: 17.4 µg/m³ (SC #70218). Lowest: 3.1 µg/m³ (SC #86604). The list shows every sensor, highest first.
Source: atmy.ai monitoring network
Sensors in the summary by network: Sensor.Community — 8 sensors.
Atmy shows the networks’ readings after the Data Hub’s quality check: test devices and sensors that fail it are left out.
110
PragueCzechia
37LiberecCzechia
14Karlovy VaryCzechia
10Cities 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.
A card with the current PM2.5 in Ostrava: it is refreshed every 15 minutes and links to this page. Paste the code into your site.
Czechia · City ranking · All pilot cities
Daily mean PM2.5 on October 21, 2026 (00:00–24:00 UTC): 14 µg/m³ from 8 sensors that passed the quality check — the same value as in the Atmy Data Hub. No. 3 of 9 cities in Czechia and No. 59 of 297 worldwide, from the most polluted.
Right now in Ostrava, PM2.5 averages 9.4 µg/m³ — “moderate” on the US EPA scale (approximate, from hourly readings). Mean of 8 sensors on the Atmy network, readings from 19:52–19:57 local time (17:52–17:57 UTC), summary prepared at 20:00 local time. Median: 8.5 µg/m³; range across sensors: 3.1–17.4 µg/m³.
The current level is “moderate” (US EPA scale, approximate). Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. This is the standard guidance of the scale, not medical advice.
Highest current reading: 17.4 µg/m³ (SC #70218). Lowest: 3.1 µg/m³ (SC #86604). 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.
Over the last 365 days with data, the mean daily PM2.5 in Ostrava was 10.5 µg/m³ — 2.1 times the WHO annual guideline (5 µg/m³). Over the last 30 days: 12.8 µg/m³. From Atmy's archive of daily city means.
In Atmy's daily archive, the cleanest month of the last year was May 2026: 4.0 µg/m³ on average.
The most polluted month of the last year was January 2026: 23.9 µg/m³ on average.
From November to March the mean daily PM2.5 was 16.9 µg/m³, from June to August 4.2 µg/m³ (last 365 days).
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
