2025 Year in Data
By Minh Nghiem, OpenAQ Data Fellow
As we step into 2026, OpenAQ reflects on a transformative year that brought air quality data to communities that need it most. In 2025, we expanded our global reach with new countries, new sensor types, and new pollutant data. This growth represents more than numbers; it reflects our commitment to tackling air inequality by making critical data accessible. From sensor networks in Honduras to the recovery of India’s extensive regulatory monitoring system, 2025 demonstrated that open air quality data can bring us closer to a world where everyone has access to the data needed to fight air inequality.
9 new countries, over 3,500 new/recovered locations, and a 33% increase in locations in low- and middle-income countries from 2024
New countries in 2025
OpenAQ strives to aggregate air quality data from as many countries as we can, with a strategic focus on low- and middle-income countries (LMICs). In 2025, we were pleased to add 94 locations in 9 new countries where we previously did not host data, all of which are LMIC-designated by the World Bank’s 2025 country income classification.
New locations in 2025
In 2025, OpenAQ introduced over 3,500 recovered/new locations, which in turn added over 86 million measurements, historical and active ingestion included.
With approximately 42% of new/recovered locations spanning 50 LMICs, 2025 was a great conclusion to a strategic period of remarkable progress in open air quality data in the world, particularly in the global south.
Country highlights in 2025
OpenAQ strives to be the best in the world in providing access to open air quality data on an open-source platform. We do face challenges, namely sentiments against or misunderstandings about open data, technical issues, and language barriers. Tapping and maintaining new sources of data across the world is not easy, but every new location brings joy and confidence that good is being done in the world.
This past year, several countries became an increasingly notable presence on the platform.
In Asia, governments and the general public are becoming increasingly aware of the adverse health effects of bad air quality, leading to enhanced air quality monitoring activities in this region. Pakistan, Laos, and India stood out in 2025, being among the top four countries with the most new or recovered locations on OpenAQ (following only the US). While the new locations added in Pakistan and Laos were almost entirely air sensors, in India we were able to recover access to the large Central Pollution Control Board (CPCB) reference-grade network.
In the Americas, the US tops the chart in having the most added/recovered locations. Yet Honduras, despite having a modest network in size, is a profound example of data growth in Central America. Thanks to Sustenta Honduras, a youth movement that is leading the establishment of a local air monitoring network across the nation, data from 34 new air sensor locations were added to OpenAQ in 2025, marking a massive growth for the country from having just 2 locations in 2024.
You can view the visual spread of which Figure 3, 4, and 5 are screenshots to see where all newly ingested/recovered air monitoring sites are located here.
Tying back to our 2022–2025 strategic plan
Increasing data coverage across strategic geographies, in particular LMICs and environmental justice communities, was a priority in OpenAQ’s last triennial strategic plan (and remains a priority moving forward). The 9 new countries added in 2025 (countries where we previously had no data, but now do) contribute to a total of 43 new countries added since 2022, raising our global coverage to 141 countries and territories. The number of active locations vary each year — locations may be turned off or become inoperable or they may no longer be open to the public — but we have been able to maintain a net increase of over 7,100 active locations from 2021 to the end of 2025, with over 15,300 locations that are actively monitoring.
These active locations added over 557 million measurements in 2025 to our database. Along with over 330,000 historical measurements added from new locations, the more than 2 billion measurements that users can now tap using the OpenAQ platform speaks to the wealth of open data that we share and that we will continue to maintain and improve.
LMIC focus
We have consistently added 7 LMICs on average to our platform annually since 2022. As shown in Figure 7, 2025 saw a record surge of 33% in new LMIC locations, the highest year-over-year increase to date. While largely driven by the EPIC Air Quality Fund and Clean Air Catalyst initiatives described below, this growth also signifies a broader trend: an increase in local air monitoring networks in LMICs fueled by civil society organizations that believe in the value of data transparency in the fight for clean air.
A remarkable year for open air sensor networks
Growth in air sensors vs. reference-grade monitors
Figure 8 demonstrates how the changing landscape of global air monitoring is increasingly defined by air sensors. While reference-grade stations still comprise 75% of OpenAQ’s total locations as of year end 2025, a massive pivot is evident: 80% of new locations added last year were air sensors, doubling the 40% seen in 2024. This shift reveals that air monitoring continues to evolve and grow beyond regulatory devices, as evidenced through the rise of hyper-local, community-led health initiatives using air sensors.
This new reality makes it essential to address data rights and ownership to ensure that air quality data benefits the broader public, not just individual device owners. You can look forward to upcoming blogs and publications about these issues.
As Figure 9 shows, on OpenAQ, air sensors account for a larger proportion of LMIC locations than they do for high-income locations. While some of this is due to OpenAQ prioritization, other reasons include the fact that the governments of upper-middle and high-income nations tend toward greater data transparency, and that efforts to fill in data gaps in low- and middle-income countries with air sensors are rapidly expanding.
Parameters¹
Beyond expanding coverage, OpenAQ aims to enrich the diversity of pollutant and meteorological data available on the platform. In 2025, while PM2.5) was the most commonly added parameter globally, deployment of sensors capturing other pollutants also increased. Although LMICs have 500 fewer newly added locations on OpenAQ than their high-income counterparts, both geographies contributed nearly the same volume of individual parameters (5,172 and 5,260 respectively). Figure 10 illustrates this, showing that new locations in high-income countries on OpenAQ in 2025 measure the three most common pollutants, whereas locations ingested from LMICs in 2025 measure a greater variety of parameters. In fact, LMICs outperformed high-income countries in new location readings of ten different parameters, including NO2, O3, black carbon, and various meteorological markers in 2025.
2 initiatives and 3 new providers
This progress could not have happened without governments all over the world making their air quality data openly available to the public, as well as partnerships with air sensor companies who facilitate the sharing of their customers’ data. You can read about government data sharing in our biennial report: Open Air Quality Data: The Global Landscape. Below, we share information on new air sensor company relationships and recent initiatives that have enabled the significant growth in air sensor data on OpenAQ in 2025.
Sensor company highlights
OpenAQ partners with air sensor companies who have an open data ethos and are willing to facilitate the sharing of their or their customers’ data. Of these partners, AirGradient, Clarity, and IQAir showed the most growth in data sharing in 2025. AirGradient led the group, facilitating the addition of approximately 3,500 locations this year (Figure 11). Additionally, we welcomed IQAir and AirQino as new air sensor data providers on the platform in 2025.
EPIC Air Quality Fund
Led by the Energy Policy Institute (EPIC) of the University of Chicago, the EPIC Air Quality Fund supports local governments and organizations to install air quality monitoring networks and use the data that is generated to spur national-level action for clean air. This fund directly enabled over 520 new locations in 2025 alone, mostly in the Global South, with more expected in years to come. To support EPIC, OpenAQ worked with 16 project partners across 12 countries, 4 of which are generating data that is among the first and/or only source of air quality data on OpenAQ for that country (Figure 12).
EPIC’s impact on OpenAQ’s ability to expand data access where it is sorely needed is most visibly seen in Africa where roughly 42% of locations with any data in 2025 come from EPIC-funded projects. Figure 13 illustrates the Fund’s impact in this continent and beyond, where EPIC locations account for the majority of active locations on OpenAQ in most countries where they were deployed.
OpenAQ has published several blogs on these amazing projects, with more to come on our Medium site.
Clean Air Catalyst
The Clean Air Catalyst (CAC) is an initiative that was funded by USAID and focused on identifying sources of air pollution, building coalitions, and empowering women as leaders in the fight for clean air in three cities: Indore, India; Jakarta, Indonesia; and Nairobi, Kenya.
CAC installed reference-grade instruments in heavily polluted urban cores and is passing ownership over to the local governments. One of CAC’s most notable contributions is its deployment of black carbon sensors, including the first monitors in Kenya and Indonesia to measure this super pollutant. Prior to 2025, OpenAQ had black carbon readings from only 236 locations, making the readings from the 7 new black carbon sensors deployed in Jakarta and Nairobi very valuable, especially as they are the first in the Global South on OpenAQ and account for 87.5% of new black carbon sites added in 2025.
The future
Expanding data acquisition remains core to OpenAQ’s work in our new 3-year strategic plan, along with equipping air quality changemakers with the tools and training to access, understand, and effectively use data on OpenAQ, especially folks in the Global South. We are grateful to our current partners and look forward to future partnerships.
See our 2026 Tech Roadmap here.
You can help us achieve our goals by pointing us to sources of open air quality data and otherwise supporting our work.
We look forward to sharing our 2026 results in a year. And we especially look forward to hearing about all of the ways our users are turning data into action!
Footnotes
¹On the OpenAQ platform, “parameters” include both air pollutants, e.g., PM2.5, NOx, O3, etc. and meteorological parameters, e.g., relative humidity and temperature. For simplicity, “parameter” will be used here and throughout the text when referring to the aggregate of both.
²Note that multiple sensing units for individual parameters may be housed in one reference monitor or air sensor, i.e., one air sensor can report PM2.5, relative humidity and temperature. This figure counts the individual sensing units that report the individual parameters on the y-axis.
