Since his first days in office, President Trump has made eliminating federal regulations a priority. His administration, with help from Republicans in Congress, has targeted environmental rules it sees as overly burdensome to the fossil fuel industry, including major Obama-era policies aimed at fighting climate change.

A New York Times analysis, based on research from Harvard Law School, Columbia Law School and other sources, counts nearly 80 environmental rules on the way out under Mr. Trump. Our list represents two types of policy changes: rules that were officially reversed and rollbacks still in progress. Nearly a dozen more rules – summarized at the bottom of this page – were rolled back and then later reinstated, often following legal challenges.

47 31 78 rollbacks completed rollbacks in process total rollbacks Air pollution and emissions 9 overturned 12 in process 21 total Drilling and extraction 10 overturned 6 in process 16 total Infrastructure and planning 11 overturned 1 in process 12 total Animals 7 overturned 2 in process 9 total Toxic substances and safety 3 overturned 3 in process 6 total Water pollution 4 overturned 2 in process 6 total Other 3 overturned 5 in process 8 total

The process of rolling back regulations has not always been smooth. In some cases, the administration has failed to provide a strong legal argument in favor of proposed changes or agencies have skipped key steps in the rulemaking process, like notifying the public and asking for comment. In several cases, courts have ordered agencies to enforce their own rules.

All told, the Trump administration’s environmental rollbacks could lead to at least 80,000 extra deaths per decade and cause respiratory problems for more than one million people, according to a separate analysis conducted by researchers from Harvard. That number, however, is likely to be “a major underestimate of the global public health impact,” said Francesca Dominici, a professor of biostatistics at the Harvard School of Public Health.

Here are the details for the policies targeted by the administration so far. Are there rollbacks we missed? Email climateteam@nytimes.com or tweet @nytclimate.

11 rules were reinstated following lawsuits and other challenges