Reporting Thresholds Disrupt European Industrial Emissions Records: Evidence for Carry-Forward Display of Below-Threshold Declarations

Pollutant registers require exact values only above reporting thresholds, so an absent numeric record can represent zero emissions, a positive release below the threshold, facility closure, or missing data. Regulation (EU) 2024/1244 introduces a below-threshold declaration to resolve this ambiguity. This study uses a counterfactual simulation based on historical proxy data to evaluate how that declaration should appear in the public record. European Pollutant Release and Transfer Register (E-PRTR) data for 2007–2024 are linked to EU Large Combustion Plants records and compared with England’s Pollution Inventory. Numeric reporting rose by 53.25 percentage points at the statutory nitrogen oxide and sulphur oxide thresholds. Among 900 comparable exits from numeric reporting, 90.0% retained positive linked emissions. A declaration shown only when status changed raised adjacent-year continuity from 42.22% to 47.02%. Carry-forward display raised continuity to 84.61%, matching annual declaration with 77.2% fewer status reports. England’s lower-threshold register confirmed positive releases below the European threshold. Carry-forward display should be the default implementation of Article 6(2), accompanied by post-implementation verification.