The authors of a study published in January have issued a correction that indicates the scientists overstated the local health benefits and lives saved due to the closure of coal-fired power plants and the addition of new natural gas units in the U.S.

The original study published in the journal Nature Sustainability found that coal-to-gas switching from 2005 to 2016 saved about 26,610 lives in the immediate vicinities of the shuttered coal plants.

In addition to carbon dioxide, coal-fired plants produce short-lived climate pollutants such as particulate matter, ozone, and the oxides of sulfur and nitrogen. While carbon dioxide is long-lived, it tends to be "well-mixed" in the atmosphere and so its impacts are not necessarily directly found in the immediate vicinity, the original study said.

But short-lived pollutants usually remain closer to the source of their emission and interact with the atmosphere and therefore can impact local human health and crop yields. Those short-lived pollutants can also affect the radiative properties of the local atmosphere and contribute to the regional climate changes, the scientists explained.

In a correction issued in June, the authors indicated that they made an aggregation error in the analysis code, which resulted in a miscalculation of the number of coal-fired units in a given area. This aggregation error caused the scientists to overestimate the impact for an individual unit, which also affected aggregated totals.

After fixing the error, the results for the mortality rates are "only significant at the more local scale," said the correction. Specifically, a unit shutdown has an impact of only within 25 kilometers of a county rather than 200 kilometers, the correction explained. So, rather than an estimated 26,600 lives being saved, the updated total is about 22,600 lives saved.