WASHINGTON — The Trump administration has formally revised a proposal that would significantly restrict the type of research that can be used to draft environmental and public health regulations, a measure that experts say amounts to one of the government’s most far-reaching restrictions on science.

The revisions made public Tuesday evening mean the Environmental Protection Agency would give preference to studies in which all underlying data is publicly available. That slightly relaxed restrictions in an earlier draft that would have flatly excluded any research that did not offer up its raw data, even if that data included medical information protected by privacy laws or confidentiality agreements.

Even with the latest changes, scientists warned that the regulation would let the federal government dismiss or downplay some of the most important environmental research of the past decades. That includes research that definitively linked air pollution to premature deaths but relied on the personal health information of thousands of study subjects who had been guaranteed confidentiality.

The proposal is one of dozens of environmental protection rollbacks that the Trump administration is scrambling to finalize before the presidential election in November. It caps more than three years of efforts to dilute scientific research, especially on climate change and air pollution, which has underpinned rules that the fossil fuel industry calls burdensome.