Air Quality: Fine Particulate Matter (PM2.5) Station Measurements

Real-time station level outdoor measurements of fine particulate matter 2.5 micrometers or less in diameter (PM2.5) reported by government entities and international organizations

  • Source: OpenAQ


The Air Quality: Fine Particulate Matter (PM2.5) Station Measurements dataset is a global dataset that shows real-time air quality data from around the world for fine particulate matter (PM2.5). It presents data collected from government and international organizations at the station level. This means the data is more accurate to specific areas than national or regional data. As of June 2017 OpenAQ data was available for 5,400 locations in 48 countries and is being continually updated with new sources.

PM2.5 are fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller. These particles come in many sizes and shapes and can be made up of hundreds of different chemicals. Some are emitted directly from a source, such as construction sites or smokestacks, while others are created from complex reactions in the atmosphere. The size of these particles allows them to get deep into the lungs, and some may even get into the bloodstream. Numerous scientific studies have linked particle pollution exposure to a variety of health problems, including: premature death in people with heart or lung disease, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function, and increased respiratory symptoms. People with heart or lung diseases, children, and older adults are most likely to be affected by particle pollution exposure.

OpenAQ is an open-source project to surface live, real-time air quality data from around the world. Its “mission is to enable previously impossible science, impact policy, and empower the public to fight air pollution.” Scientists, researchers, developers, and citizens can use these data to understand how air quality in different locations changes over time.

Resource Watch also shows continually updated air quality data from OpenAQ on inhalable particulates (PM10), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), carbon monoxide (CO), and black carbon (BC).


The fine particulate matter (PM2.5) station measurement dataset was produced and is continually updated by aggregating data from permanent outdoor air quality measures. Data was collected only from official sources, including government entities and international organizations. As of June 2017 OpenAQ data was available for 5,400 locations in 48 countries. For data to be included it had to meet three criteria:

  1. The “raw” measurement data on physical particle concentration had to be available on the originating site.

  2. The data needed to be at the “station level.” It is unacceptable if it is presented in an aggregated form for a city or region.

  3. The data needed to be continuously updated at intervals between 10 minutes and 24 hours.

After the data was collected it was put into tables. Data was collected using the source organization’s Air Quality Index (AQI) classifications. The final dataset was mapped in vector format at a subnational level with each measurement station showing local particle concentration. OpenAQ continually reviews each data source website for updated values and updates the dataset every hour.

For the full documentation, please click on the “Learn more” button.

Data shown on Resource Watch Map

Resource Watch also shows continually updated air quality data from OpenAQ on inhalable particulates (PM10), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), carbon monoxide (CO), and black carbon (BC).

Coordinates provided in the source data were used to map these data for display on Resource Watch. See the documentation on how Resource Watch processed the data on Github.


Excerpts of this description page were taken from the source metadata. Resource Watch shows only a subset of the dataset. For access to the full dataset and additional information, click on the “Learn more” button.

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Formal name

OpenAQ Air Quality Readings


  • Data on the OpenAQ Application Programming Interface (API) are left as reported by official entities. There is no review of raw data to check the Air Quality Index (AQI) used by each reporting organization. All quality control and data verification should be performed by users.

  • The dataset only includes information from permanent outdoor measurement stations. All low-cost, temporary, mobile, and/or indoor sensors are not considered in this data.

  • The OpenAQ team determined that a maximum interval of 24 hours is what is considered “real-time” data.

  • The OpenAQ dataset is open source, so it is continually being updated with new data collection sources. The quantity of sources available and number of stations mapped is variable.

Suggested citation

Hasenkopf, Christa A., David C. Adukpo, Michael Brauer, H. Langley Dewitt, Sarath Guttikunda, Alaa I. Ibrahim, Delgerzul Lodoisamba, et al. 2016. "To Combat Air Inequality, Governments and Researchers Must Open Their Data." Clean Air Journal = Tydskrif vir Skoon Lug 26 (2): 8-10. Accessed through Resource Watch, (date).



Geographic coverage

Select countries

Date of content

Varies by country and source

Frequency of updates

Varies by location (10 minutes-24 hours)


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