By Rebecca L.Root
Two years ago, Thaipat Thanasombatkul lost his son, a 29-year-old doctor, to lung cancer. He had never smoked and led a relatively healthy lifestyle.
Both father and son believed years of breathing toxic air in their hometown of Chiang Mai, Thailand, contributed to the disease. A soft haze blankets the northern city for months each year. Laden with fine particulate matter known as PM2.5, it regularly exceeds the World Health Organization’s recommended limits.
Knowing the day’s pollution levels allows people like Thanasombatkul to take steps to protect their health. The air quality readings that many relied upon most came from a reference-grade monitor at the U.S. Embassy in Bangkok. It served as a benchmark for scientists calibrating lower-cost sensors across the region and for advocates pressing the government to address dangerous pollution.
That data is no longer publicly available. In March 2025, the State Department stopped sharing air quality readings from U.S. embassies and consulates through its public mobile applications, AirNow and ZephAir. The move ended the U.S. Global Air Quality program, which had provided trusted, independent pollution data from more than 70 diplomatic posts in over 50 countries, including Thailand.
Since his son’s death, Thanasombatkul has accelerated his advocacy work on clean air, intent on ensuring that others do not suffer the same health consequences he and his son have.
“PM2.5 has heavily impacted my life by causing chronic respiratory issues and forcing me to stay indoors,” Thanasombatkul said.
Air pollution can cause cancer, heart disease, stroke, and cognitive impairment, contributing to an estimated seven million premature deaths worldwide each year. In Thailand, around 40 people die from lung cancer every day, while exceeded the WHO’s recommended PM2.5 limits for 265 another 48 are diagnosed. In 2024, Thailand out of 365 days.
But the country is relatively fortunate: It has its own national monitoring network. In many other countries, U.S. embassy monitors provided the only publicly available reference-grade air quality data. Thirty-six countries lost access to this data when the U.S. stopped publishing embassy readings. Globally, only 64% of countries monitor air pollution at al, and just 27% make that information publicly available and transparent.
The impact
Without data from the U.S. sensors, advocates like Thanasombatkul are less equipped to advocate for policies such as Thailand’s Clean Air Act that mandate cleaner air and public action.
Before he retired, Thanasombatkul was the director of Bangkok’s traffic and transport department, where he worked, as he puts it, to “protect the lungs and health of our citizens” by syncing smart traffic lights, upgrading local bike paths, and drafting pollution control regulations.
These efforts and others depend on reliable data to measure whether they are working, says Weenarin Lulitanonda, cofounder of the Thailand Clean Air Network.
“You can’t manage something which you can’t measure,” Lulitanonda said. “Without it, you’re working blind.
Lulitanonda was part of the conversations nine years ago that led to the installation of a PM2.5 monitor in Bangkok’s U.S. Embassy. While Bangkok has other air monitoring systems implemented by the government and private companies, the embassy sensor was of the highest quality available.
“For a city like Bangkok, losing a registered grade sensor is a big deal,” said Achim Haug, founder of AirGradient, which supplies affordable and accurate air quality monitors globally. “There are way too few of these high-quality reference stations in a lot of global south countries.. That’s affecting a lot of global health impact studies.” In 17 countries, including Myanmar, the Democratic Republic of Congo, and Togo, the sensors provided the only source of public air quality data.
In the DRC, where PM2.5 concentrations are the highest in Africa, advocates like Paulson Kasereka are struggling with the loss of reference-grade data.
“Its withdrawal has constituted a huge gap for our work because we are no longer able to calibrate the air quality data that we are continuously collecting,” said Kasereka, executive director of the nonprofit WASARU, which promotes community-driven solutions on the nexus of air quality, climate resilience, and sanitation. Without the data provided, his team has less evidence to raise awareness and push for policy changes that could improve air quality.
Ghana is facing a similar problem. The U.S. monitor affixed to the U.S. Embassy building in the capital of Accra was the only open-source data available, said Colins Gameli Hodoli, founder of Clean Air One Atmosphere. His organization is developing low-cost sensors and a mobile application that would allow the public to track air quality and take steps to avoid toxic pollution. But the model depended on access to higher-caliber data from the U.S. reference-grade monitors to calibrate and validate readings.
“Now that we don’t have any open-source data, particularly from that environment, it will be difficult to do that,” Hodoli said.
The loss also impacts U.S. citizens, said Janet McCabe, former deputy administrator of the U.S. Environmental Protection Agency.
The Global Air Quality program was born in 2008 out of a request from embassy workers in Beijing who feared the country’s pollution levels were impacting their health and couldn’t find air pollution data from the Chinese government.
“It prompted the government of China to start making air quality data more available to people … and the other embassies started saying ‘Hey, we want one too,” McCabe explained.
At the State Department, the data helped determine hardship pay for embassy staff and informed daily decisions about spending time outdoors. Publicly, the readings alerted residents to dangerous air quality in real time and underpinned scientific research and environmental policy.
“For the cost of it and for the fact that it was intended to and it does protect Americans and American families who are serving their country by serving in the embassies, it seemed like a foolish and uncaring and unnecessary decision to make,” McCabe said.
By drawing attention to poor air quality, the monitors helped spur policy action and public awareness, generating substantial health and economic benefits, according to a 2022 research article. The report estimated savings of about $127 million per city and concluded that “monitoring and information interventions that draw attention to poor air quality in developing countries can generate substantial benefits.”
The loss of the U.S. monitors is already shaping demand for replacement systems. In the current funding round for the Air Quality Fund at The University of Chicago’s Energy Policy Institute, or EPIC, more than 75% of applicants proposed projects in countries that lost a U.S.-operated reference-grade monitor, said Christa Hasenkopf, founding director of EPIC’s Clean Air Program. The fund supports government and community projects to install air quality monitors, with the goal of reaching billion people with air quality data by 2030.
“In our interviews with applicants, the loss of the State Department program came up frequently as a barrier for their work,” Hasenkopf said.
The cost
While the State Department cited budget constraints as justification for discontinuing the program, Diane Archer, a senior research fellow at the Stockholm Environment Institute, questions that notion. Reference-grade air quality monitors can cost between $15,000 and $40,000 to purchase, with annual operation and maintenance costs of approximately $15,000 per monitor. In many cities, however, the upfront investment had already been made before the data was taken offline.
“It seems a shame because all the physical equipment is already there and up and running,” Archer said.
Archer keeps a low-cost air quality sensor on the balcony of her Bangkok home, using it to decide whether it is safe for her family to spend time outdoors, particularly during the early months of the year when smoke from agricultural burning in northern Thailand drifts south toward the capital.
Research suggests the embassy monitoring program generated benefits for the public beyond health. The installation of embassy air quality monitors was associated with lower post hardship differential payments for U.S. diplomats, which are based in part on environmental conditions. Researchers estimated the differential fell by 7.6% after monitors were installed – equivalent to about $1,477 per diplomat annually, generating a median savings of roughly $34,000 per embassy each year. More broadly, the Clean Air Fund estimates that every $1 invested in cleaner air generates approximately $30 in economic returns through reduced health care costs and increased productivity.
“I don’t really see this as a partisan issue,” AirGradient’s Haug said. “Clean air is in everybody’s interest.”
Hasenkopf hopes other donors will step in to measure air quality. “There is a massive opportunity to rebuild this data infrastructure better with more in-country monitoring and data ownership that will make the global air quality system less brittle to policy swings from a single country,” Hasenkopf said. “If we learned anything from the big, positive health impacts of this tiny State Department monitoring program, the effort would be completely worth it.”