Lappalainen "et al." (2009) found N-Tat in 15.4% (4/26) of a sample from Södermanland, 12.5% (3/24) of a sample from Västmanland, 12.1% (4/33) of a sample from Uppsala, 7.8% (4/51) of a sample from Gothenburg, 7.0% (3/43) of a sample from Norrbotten, 6.8% (5/73) of a sample from Skåne, 6.6% (15/228) of a sample from Stockholm, 6.3% (3/48) of a sample from Sydnorrland, 6.3% (2/32) of a sample from Västerbotten, 6.3% (2/32) of a sample from Örebro, 5.9% (3/51) of a sample from Värmland/Dalarna, 5.4% (2/37) of a sample from Östra Götaland, and 5.1% (2/39) of a sample from southeastern Sweden (Kalmar, Gotland, Kronoberg, and Blekinge). They did not find any instance of N-Tat in their samples from Jönköping (0/28), Malmö (0/29), Halland (0/34), or Västra Götaland (0/75).