The data pause weakens air quality monitoring efforts in 44 countries across the globe, and leaves six without any monitoring at all
By Katherine Hasan, Analyst, CREA; Lauri Myllyvirta, Lead Analyst, CREA
On 4 March of this year, AirNow – a website run as part of a partnership between United States government agencies led by the U.S. Environmental Protection Agency (EPA) that had heretofore reported data collected from air quality monitors installed at U.S. embassies and consulates throughout the globe – suddenly went dark. The following day, the U.S. Department of State (DoS), which oversaw the program, said in a statement to the press that it would no longer transmit the collected data to the AirNow app and other platforms.
According to the DoS statement, the stop in data-sharing was due to ‘funding constraints that have caused the Department to turn off the underlying network’. The statement added that embassies and consulates were directed to keep their monitors running and the sharing of data could resume in the future if funding was restored.
A DoS spokesperson later told CBS News that the U.S. embassy air monitoring data would continue to be collected and would be ‘made available when there is a secure and reliable way to transmit it’ and that they were ‘evaluating other transmission options’. The spokesperson also said that air quality monitoring is ‘only one of a number of tools the Department uses to ensure the health and safety of our staff’.
When the indefinite pause on data sharing started, scientists and citizens of the countries where U.S. embassy sensors had been present instantly lost all access to regulatory-grade air quality (AQ) data – in the case of some nations, they now have no access to any air quality data at all.
Study shows AirNow brought PM2.5 levels down, saved USD 465mn and avoided 895 premature deaths in a median city across the analysed US embassies assuming benefits to the entire city
A 2022 study by researchers at Carnegie Mellon University and The University of Queensland evaluated the impacts of the AirNow program at over 40 U.S. diplomatic posts around the world that had only had low-quality monitoring in place previously.
The scientists that conducted the study used satellite-derived measurements of pollution in 466 cities in 136 countries, of which 50 cities in 36 countries had US embassy sensors installed, to evaluate the impacts of this experiment in air quality monitoring and reporting. To calculate the reductions in pollution and the associated benefits that the program yielded, they looked at changes in the compensation U.S. diplomats received for difficult conditions abroad, including pollution, and premature mortality avoided in the embassy cities.
The study concluded that the implementation of the embassy monitors along with the sharing of data contributed to decreases in fine particulate matter (PM2.5) concentrations of 2 to 4 micrograms per cubic meter in the host countries, a significant decrease. Figure 1 illustrates the findings for PM2.5 reduction, with such effects increasing over time.
Figure 1 – Effect of air quality monitoring on PM2.5 at embassies in non-OECD countries
At the same time, the researchers estimated that in 2019, the annual monetised benefit of the decline in premature mortality due to this reduction in pollution reaches at least USD 127 million for the median city across the analysed US embassies assuming only people within 10 km of the embassy site are benefiting, and up to USD 465 million assuming the entire city benefits.
In terms of premature mortality, the analysis estimates a median value of at least 303 avoided deaths from 10 km radius, and up to 895 avoided deaths from the entire city. These findings highlight the significance of air quality data availability, particularly in low- and medium-income countries.
AirNow data catalysed a dramatic improvement in China’s air quality
Beijing forms an especially notable case study of what AirNow’s regulatory-grade data can accomplish. In 2008, the U.S. Embassy there began tweeting hourly air-quality updates from the newly-installed pollution monitor, information that local residents previously had no access to. Then, in 2010, the account – AirBeijing – drew overwhelming online attention when it tweeted that the air quality on 11 November was ‘Crazy Bad’, a description the program developers had written jokingly under the assumption that it would never be triggered
While the embassy monitor information was targeted at U.S. expats, local Chinese citizens quickly picked up on the updates and began calling on the government to address the air pollution issue. Following the ‘Crazy Bad’ incident, China’s State Council released a national air quality plan as well as significantly expanded the national air monitoring network.
Between 2018 and 2024, China’s annual average PM2.5 concentrations declined from 41.2 to 31 – improving from a very unhealthy to an unhealthy range of air quality, according to IQAir data.
‘I’ve never seen an initiative of the U.S. government have such an immediate, dramatic impact in a country,’ then U.S. Ambassador to China Gary Locke told the Washington Post in 2013.
In the time since the Beijing example first showed how embassy data could lead to meaningful action on air pollution, the DoS has installed more than 50 monitors in 38 countries around the world.
U.S. data pause in March weakens access to regulatory-grade air quality monitoring in 44 nations, at least 6 have no data access at all
While low-cost air quality monitors play a significant part in promoting air quality awareness, the regulatory-grade monitors installed at U.S. embassies help to calibrate and validate the low-cost monitors. In the case of Beijing, they also served as the only publicly accessible, independent data source for verifying the accuracy of government-reported pollution levels.
The full list of 28 countries affected by the US embassy data halt and 6 countries entirely losing air quality monitoring access as of 2025, is provided in Table 1.
Table 1 – Tabulation of countries affected by U.S. embassy data halt in 2025
CREA’s assessment of historical AQ monitoring data available from the US embassy sensors shows that 11 of the U.S. embassy monitors have been shut down at different time periods before 2025. According to a recently released OpenAQ analysis, there were 70 such monitors actively monitoring air quality in 50 countries as of January 2025.
With the halt of AirNow data sharing as of 2025, six countries lost access to air quality monitoring entirely, 28 countries lost access to government regulatory-grade air quality monitors, and the remaining 16 countries are in urgent need to review access to regulatory-grade instruments.
Figure 2 – Distribution of ambient air quality monitoring across the globe
According to OpenAQ’s Global Landscape report released in December 2024, 71 countries, in which a total of nearly one billion people reside, do not monitor their air quality. Out of 127 countries with continuous monitoring, not all governments share air quality data openly and publicly; 18 countries do not share their data at all.
OpenAQ also pointed to the U.S. embassy’s initiative as a vital public health tool, filling the gap in global air quality monitoring. In at least 13 countries, the U.S. embassy monitors had and have been serving as the sole source of government-sponsored, regulatory-grade air quality data. Among these countries, nine are located across Africa (Côte d’Ivoire, Guinea, Mali, Burkina Faso, Togo, Sudan, Gabon, Chad, and Democratic Republic of Congo), three in Asia (Turkmenistan, Afghanistan, and Iraq), and lastly one in the Caribbean (Curacao). To note, other than the six countries losing access as of 2025, five had entirely lost access prior to this year, namely Curacao, Afghanistan, Sudan, Mali, and Gabon.
The monitors not only serve U.S. diplomats, travelers, and residents abroad, but also complement existing government monitoring capabilities, supporting efforts in solving air pollution worldwide. Based on the historical data available through AirNow, the DoS has deployed a total of 89 monitoring stations in 61 countries throughout the years (See Figure 3).
OpenAQ further highlighted that in the most populated countries that lacked government air monitoring, air pollution was among the top seven risk factors for death and disability in that country. On average, air pollution shortens lives by nearly two years across the globe. With health burdens being unequally distributed, such pollution has greater impacts on pregnant women and their unborn babies, young children, the elderly, and individuals with pre-existing conditions, as well as lower-income communities and citizens of countries where pollution tends to be higher.
Figure 3 – Additions of U.S. embassy monitoring stations over the years
Regulatory-grade monitoring pays for itself
The DoS cited budget constraints as the key factor in taking the AirNow data offline. However, a former U.S. administration official, Deputy Special Envoy for Climate, Rick Duke, described the cost to maintain the systems as ‘trivial’.
Taking it a step further, Dr Andrea La Nauze, Associate Professor of Economics at Deakin Business School in Australia and one of the lead researchers on the AirNow impacts study, said that their work showed that the monitors in fact ‘effectively paid for themselves’.
La Nauze explained that this is because the DoS provides U.S. diplomats hardship pay for living conditions that are worse than those in the United States, such as access to health care. One of these conditions is air quality.
‘Because air quality improved in the locations with monitors, we suspected that the hardship payments to U.S. diplomats declined after they were installed,’ La Nauze said. ‘We do indeed find that [hardship payments] declined in cities receiving an embassy monitor relative to comparable cities that did not receive an embassy monitor.’
La Nauze added that the research team’s calculations showed that the monitors saved the median embassy USD 33,971 per year in hardship payments, while the monitors themselves have an annualized cost of USD 9,712. Similar to effects on PM2.5 reduction, reduction on hardship pay for diplomats also grew larger over time.
Figure 4 – Effect of air quality monitoring on post hardship differential received by U.S. diplomats stationed in non-OECD countries
For low-income countries, high-grade air quality data is also essential to make the case for international support for clean air and clean energy efforts, and to demonstrate their effectiveness.
These numbers serve as a potent reference to governments as to the financial and public health benefits of filling the monitoring gap left by the U.S. themselves. Not only could they drastically reduce healthcare costs for their own workers, they could also significantly improve the air quality in the cities that those monitors are hosted in, thereby lowering that city’s economic burden. Moreover, they would join an international community of countries whose data sharing contributes to more robust and effective air quality monitoring worldwide.
The case for AirNow-reliant countries to ramp up AQ efforts
IQAir’s 2024 report on World Air Quality includes annual city-level averages of PM2.5, showing not only how air quality progresses in communities around the world, but also revealing how monitoring has grown over the past eight years from 2017 to 2024.
The number of cities with sufficient levels of monitoring to enable annual averaging of PM2.5 concentration has grown four-fold, from 2,045 cities in 2017 to 8,234 cities in 2024. Moreover, the findings show the significance of access to air quality monitoring data, strongly indicating rapidly growing public awareness and demand for transparency.
Figure 5 – IQAir city-level annual air quality averages 2017-2024
The U.S. State Department played a significant global role in initiating this groundbreaking worldwide initiative. Now, CREA urges the governments in cities and countries who have lost their only source of regulatory-grade, publicly accessible air quality monitoring data to ramp up city-wide and nationwide initiatives to expand monitoring capabilities and improve existing efforts on air quality data sharing and disclosure.
Furthermore, countries with existing monitoring capabilities should prioritise transparency by ensuring air quality monitoring data – both real-time and historical – is available for public access.
Lauri Myllyvirta, Lead Analyst at CREA, said, ‘High-quality, open air quality data is the cornerstone of the global fight against air pollution. With the loss of access to the AirNow data and no clear return date on the horizon, there’s an urgent need to start high-grade air quality measurements to maintain data availability and sustain the manifold benefits of the embassy monitoring program.
‘Monitoring capability is lost in at least 11 countries, while a further 18 countries with government monitoring still need to make their measurement data publicly accessible, and 56 countries to make data fully transparent. This is an opportunity for both national stakeholders and other international actors to step up.’
About the data
The analysis on air quality government monitoring was based on two main datasets – (1) OpenAQ 2024 Global Landscape Report Worksheet [public], (2) AirNow US Embassy Historical Data. The two datasets were merged to assess the state of government air quality monitoring, whether monitoring is available only from the national government or from both national government and the U.S. embassy, and whether the data is publicly accessible and fully transparent. AirNow historical data is also used to map additions of sensors in cities in various countries throughout the years.
IQAir’s data for the world’s most polluted cities with PM2.5 annual averages available from 2017 to 2024, is utilised to assess how monitoring coverage has evolved over time. Jha and La Nauze’s 2022 publication, “US Embassy air-quality tweets led to global health benefits”, provides city-wide benefits from US embassy sensor installation in terms of PM2.5 reduction and monetary savings from diplomat hardship pay.