Study design and exposure procedures
The study was performed employing a double-blinded, randomised cross-over design, with each participant undergoing two controlled exposures, once to filtered air and once to wood smoke, with at least 3 weeks apart. Exposures lasted 2 h and were carried out in a stainless-steel exposure chamber (15.3 mWood smoke was generated in a common residential Swedish wood stove, commonly installed during the 1990s, fired with birch wood logs (16–18% moisture content) under incomplete combustion conditions, targeting a PM