Posted by Oscar Sjöberg on · 4 min read
Winter road sand, ground into dust by traffic, is the leading cause of dangerous PM10 spikes in Stockholm each spring. Real-time monitoring networks can help cities act before conditions turn unhealthy.
Spring is back in Stockholm — and so is a familiar air quality problem. As temperatures climb above zero and roads dry out after winter, the sand spread to prevent icy conditions gets pulverised by traffic into fine dust particles. These particles build up in the air of busy streets, reaching levels that pose real health risks, especially for people with asthma, heart conditions, or other respiratory issues.
A recent Aftonbladet report shone a spotlight on this every-year pattern, confirming what air quality researchers have documented for years: road sand, not factory smoke or diesel fumes, is the main driver of Stockholm's worst pollution episodes in late winter and early spring.
The Numbers Tell the Story
According to SLB-analys data from 2024, WHO health guidelines for PM10 were exceeded at every street-level monitoring station in Stockholm — even though the less strict legal EU limit was technically met. The national "Clean Air" environmental target was also missed. And under the EU's new air quality directive (2024/2881), stricter PM10 limits must be achieved by 1 January 2030.
What Is Actually Happening?
Every autumn, Swedish municipalities sand roads and pavements to prevent accidents on ice. That makes perfect sense in winter. The problem comes in spring, when roads dry out and traffic grinds all that accumulated sand into fine airborne dust.
Studded winter tyres make things significantly worse — they not only pulverise the sand but also wear down the asphalt surface itself. The resulting particles, known as PM10 (under 10 micrometres) and PM2.5 (under 2.5 µm), become airborne and build up on streets with tall buildings on both sides, where there is little wind to carry them away. Hornsgatan and the E4/E20 Essingeleden are historically the worst-affected streets in the city.
