PM10 after winter-sanding and winter-salting of roads: the Commission sets out how to demonstrate and subtract this contribution from exceedances — coarse PM fraction method (50 % of the PM10 minus PM2.5 difference) or chemical analysis of PM10 samples
Commission Implementing Decision (EU) 2026/2468, published on 6 November 2026, lays down under the Ambient Air Quality Directive (EU) 2024/2881 the technical details of the methodology for determining the contribution of particles re-suspended into the air after winter-sanding or winter-salting of roads. Only after such a demonstration can an exceedance of the daily or annual PM10 limit value be attributed to road sanding or salting. The decision enters into force on 26 November 2026.
- Directive (EU) 2024/2881 allows the contribution of winter-sanding or winter-salting of roads to PM10 exceedances to be subtracted when assessing compliance with limit values, and zones with such exceedances to be excluded from the obligation to establish an air quality plan — provided that reasonable measures have been taken to lower PM10 concentrations.
- The assessment day is a day on which the daily PM10 limit value is exceeded at a sampling point. A Member State must show sanding or salting before that day in the winter season (for salt also the timing of the most recent application and temperature, precipitation and road-surface conditions up to the assessment day), a dry road surface on the assessment day, the proximity of the sampling point to the treated area and any long-range contribution, and that no other source contributed significantly to the higher PM10 concentrations.
- Where data for other methods are not available, the sanding contribution may be determined with the coarse PM fraction method: coarse PM is the difference between PM10 and PM2.5 concentrations, and 50 % of this fraction is attributed to winter-sanding. Conditions: a coarse fraction higher than at sampling points not influenced by sanding and a PM2.5/PM10 ratio of 0.5 or less; PM10 and PM2.5 sampled and measured at the same point with the same or an equivalent method (without PM2.5 measurements — an estimate from the PM2.5/PM10 ratio at a comparable point); studded tyres not used or at most 1 % of tyres in use.
- The salting contribution may be determined by chemical analysis: information on the chemical composition of the salt used, PM10 samples collected on each affected day (at the influenced sampling point or at one with similar characteristics) and analysed with the reference method or an equivalent method, and an appropriate calculation of the salting-material concentration for each day.
- The contribution is determined at each sampling point for each assessment day and expressed in µg/m³; data from measurements or modelling must meet the data quality objectives of Annex V to the directive. An exceedance is attributed to sanding or salting only if the adjusted daily PM10 concentration does not exceed the limit value; the adjusted annual mean is calculated from the adjusted daily concentrations, without removing those days from the exceedance statistics.
- Member States submit technical reports to the Commission: zones and sampling points, the number of daily exceedances and daily and annual concentrations before and after subtraction, a description of the method, quality control and assurance, an uncertainty analysis (margin of error, confidence intervals) and evidence of measures to reduce dust — such as optimised sanding and salting, snow removal, dust binding and street cleaning. Member States’ best practices are collected in a technical support document of November 2026.