Ultrafine Particles in Viennese Gastronomy after Introduction of a National Smoking Ban

Background: Ultrafine particles have a substantial influence on the pathogenesis of diseases from ambient air pollution including personal and indoor tobacco smoke. In public rooms such as gastronomy venues without complete smoking ban, the main source of ultrafine particles is cigarette smoke. Objectives: In accordance with the research question if the legislative smoking ban reduced ultrafine particle pollution in Viennese bars, cafés and pubs, the effectiveness of this ban for the protection of nonsmokers was evaluated. As a further objective, the comparison with the ultrafine particle concentrations in smoking and non-smoking areas before and after the general smoking ban was relevant, whereby the data from the survey period April to October 2019 were used. Hereby, the effectiveness of the measure could be derived from the direct comparison of the earlier and the current recordings. Methods: 2 years after the national Non-Smoking Protection Law in November 2019 had gone into force, the indoor exposures with ultrafine particles were surveyed in 22 Viennese bars/discotheques, 5 cafés and 12 pubs/restaurants and bars. By unannounced and undercover measurements over 20 minutes each, these well frequented gastronomy locations were investigated between October 2021 and February 2022. The concentration of ultrafine particles (PNC, pt/cm³), the corresponding diameter (10 - 300 nm) and lung deposited surface area (LDSA) were recorded via Miniature Diffusion Size Classifier (miniDiSC®) in all three types of locations. Results: The ultrafine particle loadings in 2021/22 in the three location types were not significantly different any more. Two years after the ban the median PNC (pt/cm³) was 19,751 in bars, 18,854 in cafés and 19,357 in pubs. The average diameter (AD, nm) was 54.17 in bars, 44.27 in cafés and 52.08 in pubs. For average LDSA (µm²/cm³), the values were 51.65 in bars, 35.76 in cafés, and 60.71 in pubs. 2019 data had shown significantly higher median values for PNC (pt/cm³) for smoking locations at 72,802 versus non-smoking areas at 27,776 and non-smoking locations at 18,854. Similarly, smoking locations showed significantly higher values for AD (nm) at 78 versus non-smoking areas at 62 and non-smoking locations at 52. For average LDSA (µm²/cm³), smoking locations also had the highest values at 402.0 versus non-smoking areas at 108.0 and non-smoking locations at 51.9. From comparison of data, it was possible to derive the UFP concentrations above which a hospitality indoor area - regardless of its declared status - may be classified as polluted by nanoparticles (tobacco smoke): For PNC, 34,435 pt/ cm³, for average diameter 67.45 nm and for LDSA 163.68 µm²/cm³ are proposed as cut-off values. Conclusion: The national smoking ban significantly improved air quality in Viennese hospitality venues. Two years after the ban ultrafines were comparably low and not significantly different between bars, cafés and pubs, whether they were used before for smoking or not. The decrease of ultrafine particle pollution was attributed to regular non-smoking in localities. Some outliers of the present investigation after the smoking ban indicated, that control of compliance with the law has to be continued.