The U.S. government will stop sharing air quality data gathered from its embassies and consulates, worrying local scientists and experts who say the effort was vital to monitor global air quality and improve public health.

In response to an inquiry from The Associated Press, the State Department said Wednesday that its air quality monitoring program would no longer transmit air pollution data from embassies and consulates to the Environmental Protection Agency's AirNow app and other platforms, which allowed locals in various countries, along with scientists around the world, to see and analyze air quality.

The change was "due to funding constraints that have caused the Department to turn off the underlying network" the department said in a statement. However, it added, embassies and consulates were directed to keep their monitors running and the sharing of data could resume if funded is restored. The funding cut, first reported by The New York Times, is one of many under President Donald Trump.

The U.S. air quality monitors measured dangerous fine particulate matter, known as PM2.5, which can penetrate deep into the lungs and lead to respiratory diseases, heart conditions, and premature death. The World Health Organization estimates that air pollution kills around 7 million people each year.

Reaction was immediate from scientists who said the data were reliable, allowed for air quality monitoring around the world and helped prompt governments to clean up the air.

Bhargav Krishna, an air pollution expert at New Delhi-based Sustainable Futures Collaborative, called the loss of data "a big blow" to air quality research.

"They were part of a handful of sensors in many developing countries and served as a reference for understanding what air quality was like," Krishna said. "They were also seen to be a well-calibrated and unbiased source of data to cross-check local data if there were concerns about quality," he added.

"It's a real shame," said Alejandro Piracoca Mayorga, a Bogota-based freelance air quality consultant. U.S. embassies and consulates in Lima, Sao Paulo and Bogota had the air monitoring. "It was a source of access to air quality information independent of local monitoring networks. They provided another source of information for comparison."

Khalid Khan, an environmental expert and advocate based in Pakistan, agreed, saying the shutdown of air quality monitoring will "have significant consequences."

Khan noted that the monitors in the city of Peshawar in Pakistan, one of the most polluted cities in the world, "provided crucial real-time data" which helped policymakers, researchers and the public to make decisions on their health.

"Their removal means a critical gap in environmental monitoring, leaving residents without accurate information on hazardous air conditions," Khan said. He said vulnerable people in Pakistan and around the world are particularly at risk because they are the least likely to have access to other reliable data.

In Africa, the program provided air quality data for over a dozen countries including Senegal, Nigeria, Chad and Madagascar. Some of those countries depend almost entirely on the U.S. monitoring systems for their air quality data.

The WHO's air quality database will also be affected by the closing of U.S. program. Many poor countries don't track air quality because stations are too expensive and complex to maintain, meaning they are entirely reliant on U.S. embassy monitoring data.

In some places, however, the U.S. air quality monitors propelled nations to start their own air quality research and raised awareness, Krishna said.

In China, for example, data from the U.S. Embassy in Beijing famously contradicted official government reports, showing worse pollution levels than authorities acknowledged. It led to China improving air quality.