A database of federal law enforcement officer misconduct records. A survey measuring physical, sexual and emotional violence against children and youth. Real-time pollution readings collected by air quality monitors from US embassies around the world.

These are among the hundreds of federal datasets that the Trump administration has taken down or altered as part of its aggressive campaign to wipe all mentions of data findings that do not align with the administration’s priorities.

Over the past year and a half, at least 28 federal datasets have been deleted and another 338 data collections have been modified, according to an online tracker released last week from dataindex.us, a group of data policy experts, researchers and developers that formed last year to monitor changes to government data.

“We’re at a very vulnerable point as a nation,” said Denice Ross, former US chief data scientist under the Biden administration and a cofounder of dataindex.us. “We’re facing a future where we are not going to have the information that we need to make decisions that will save lives and benefit American communities.”

The tracker includes detailed information about deleted or altered datasets from more than 60 federal agencies that span the environment, labor, law enforcement and other topics. But datasets on health appear to be the most affected by the Trump administration’s crackdown, comprising about 40% of the total number of terminated or altered data collections tracked by dataindex.us.

One of the main changes to these health datasets is that they no longer collect information on queer and trans people – as part of Donald Trump’s executive order “Defending Women from Gender Ideology Extremism and Restoring Biological Truth to the Federal Government”.

Multiple Centers for Disease Control and Prevention (CDC) surveys, for example, have removed questions about respondents’ gender identity. These include the National HIV Surveillance System, the primary source of case data for HIV infections, the National Violent Death Reporting System, the CDC Diabetes Prevention Recognition Program, the National Intimate Partner and Sexual Violence Survey and specific surveys evaluating Prep uptake among gay men and in communities of color.

In addition, there are at least four health datasets that are no longer being updated at all, including the Substance Abuse and Mental Health Administration’s (Samhsa) Drug Abuse Warning Network, a surveillance system that doctors and public health researchers used to track drug-related emergency room visits in near real-time to spot emerging overdose trends.

“These data are critical for identifying emerging epidemics and what parts of the population are most vulnerable to different types of health conditions,” said Thomas Babor, a professor emeritus at the University of Connecticut who specializes in public health and addiction.

“We need to know what direction the trend is going, whether it’s the beginning of an end; we need to learn from prior episodes of epidemics and how they were responded to and what impact the responses had,” Babor said. “Taking down, even temporarily, some of the most important surveys that we have, especially for comparative purposes, is like we’re erasing our institutional memory for public health.”

Other deleted datasets include the US Department of Agriculture’s twice-annual survey of farm employers that counted the number of farmworkers employed and their wages that informed the minimum pay rates for H-2A visa workers and a National Center for Education Statistics (NCES) survey of the pay and working conditions of teachers and principals at public and private schools across the country.

Christopher Dick, a cofounder of dataindex.us and former chief of the population evaluation, analysis and projections branch at the Census Bureau said they launched the online tracker because it’s difficult to know exactly how many federal datasets have actually been deleted.

Government agencies aren’t required to notify the public when data collections are terminated, and some datasets have simply stopped updating because of a lack of staffing while others have been quietly pulled from federal websites with little notice. Some federal datasets also change or update on a regular basis, so it can be hard to figure out what is actually permanently deleted compared to a regular update.

“The question we’re trying to answer is: are certain datasets being taken away that have an impact on the American people?” Dick said.

The group identified important deleted or altered datasets through a combination of research about how the dataset was used, crowdsourcing from media reports, government employees, and people who used the datasets, monitoring social media, and tracking notices posted about proposed regulations from the Office of Information and Regulatory Affairs.

The dataindex.us tracker is not a complete list, and is likely still an undercount of all the deleted or altered datasets there are, said Ross. But the hope is the tracker is just a starting point.

“We want people who depend on different datasets, some of which might be sort of obscure, to let us know what corners to look in because we don’t have full visibility,” Ross said.