Summary

In 2022, the Joint Nordic screening group decided to perform a Nordic study on short-, medium- and long-chain chlorinated paraffins (SCCPs, MCCPs, LCCPs) in urban air. A previous study performed on behalf of screening group in 2019 observed higher concentrations of chlorinated paraffins (CPs) in air samples from an urban site than from remote sites (Schlabach et al. 2022). It was then suggested that tire wear particles could be the source for the elevated urban concentrations.

The focus of the study in 2022 was to collect data to improve the understanding of sources for CPs in air by: (1) comparing concentrations measured in wintertime when studded tires are used and in summertime when normal tires are used, (2) comparing data from three capitals in the Nordic countries, and (3) compare urban air concentrations to air concentrations in a car tire testing facility. All the member countries were invited to participate but based on the possibilities to collect active air samples in urban locations, it was decided to collect air samples from Helsinki (Finland), Reykjavik and Reykjanesbær (Iceland) and Oslo (Norway). Samples were collected in February–March 2022 and May–August 2022. The sampling time for each sample was 48 hrs and 3–6 samples were collected per site and season.

Table 1: Detection frequency (as %) of SCCPs, MCCPs and LCCPs in air samples from urban sites (URB) in wintertime and summertime.

Detection frequencies from the air samples are shown in Table 1. Lower detection frequency was observed in summer than in winter. The measured concentrations were highest for MCCPs in Helsinki and LCCPs at the urban site in Reykjavik while the lowest concentrations were measured for SCCPs and LCCPs at the urban site in Oslo.