Air quality in Chofu, Japan today

Mr. Duck’s Air Quality Score

Moderate air today for Chofu, Japan

⚠️ This website is currently under active development. Some data may be incomplete or temporarily inaccurate. For health-critical decisions, please verify information through official government or environmental sources.

Categories follow US EPA AQI breakpoints for PM (estimate from latest valid measurements; this project does not compute EPA NowCast/24-hour AQI yet).

This friendly indicator summarizes the latest city readings. For health guidance, please see: EPA AirNow or WHO.

Air quality today

The air quality in Chofu is currently classified as Moderate. The main pollutant identified is PM2.5 (fine particles). Measurements show a PM2.5 concentration of 10.0 µg/m³, based on nine valid observations reported through OpenAQ.

This assessment reflects the latest available data for the city. This page is informational; for health guidance, use official sources such as EPA AirNow or WHO.

Latest sensor values

PM categories follow US EPA AQI breakpoints, shown here as an estimate derived from the latest valid measurements (this project does not compute EPA NowCast/24-hour AQI yet).

What the data includes

The dataset for Chofu includes five measured pollutants – carbon monoxide (CO), nitrogen oxide (NO), nitrogen dioxide (NO₂), total nitrogen oxides (NOX) and fine particulate matter (PM2.5). In total nine individual sensor readings are available, coming from two distinct monitoring locations. The most recent timestamp across all pollutants is 2026‑02‑10 22:00 UTC, and each entry notes that the data were “Updated within 3 days,” indicating a uniformly fresh snapshot for this reporting period.

For the nitrogen species the values are tightly clustered. NO ranges from a minimum of 0.001 ppm to a maximum of 0.002 ppm, with a median of 0.0015 ppm and the 10th‑90th percentile band spanning just 0.0011–0.0019 ppm. NO₂ is reported at a single value of 0.019 ppm, while NOX varies only slightly between 0.020 ppm and 0.021 ppm (median 0.0205 ppm, 10th‑90th percentile 0.0201–0.0209 ppm). PM2.5 shows a broader spread: measurements range from 4.0 to 10.0 µg/m³, with a median of 7.0 µg/m³ and the interdecile interval covering 4.6–9.4 µg/m³. CO is represented by one reading of 0.3 ppm.

The coverage across pollutants is uneven: NO, NO₂, NOX and PM2.5 all come from a station in 深大寺南町 (Chofu‑Shinjuku area), whereas the CO measurement originates from a different site in 小金井市東町. Because only two locations contribute data, spatial variation within Chofu cannot be captured fully; conditions may differ elsewhere in the city or at other times. Nonetheless, the dataset provides a recent, point‑in‑time picture of key air quality constituents for the areas where sensors are installed.

Learn more about sources and filtering: About the data.

Trusted references: WHO (Air pollution) · US EPA AirNow · European Environment Agency (Air)

Latest sensor values (bars)

PM categories follow US EPA AQI breakpoints, shown here as an estimate derived from the latest valid measurements (this project does not compute EPA NowCast/24-hour AQI yet).

Data notes

The data shown reflects nine valid measurements and is updated within 3 days, with the latest values recorded at 2026‑02‑10T22:00:00+00:00. While these readings give a current overview of air quality in Chofu, conditions can differ across neighborhoods and change throughout the day, so this snapshot may not represent every location or moment within the city.

OpenAQ station rows