Background:
In November 2019 smokefree hospitality industry went into force in Austria without exceptions for roofed spaces surrounded by walls >50%. The legislation bans also shisha, HTPs and e-cigarettes. In Vienna compliance increased at first from 95% to 99% within one month, but seemed to decrease again after surveillance authority had stopped controls.

Objective:
Therefore we tested air quality repeatedly in a number of bars, cafes, discotheques, pubs, and restaurants in Vienna and compared PM10, PM2.5, PM1, and PNC & LDSA of ultrafines with concentrations found indoors before the ban and with current outdoor values. 2019-2021 in 39 venues at identical locations significant declines in both fine and ultrafine particle concentrations were found in the former smoking areas for all parameters as well as in the former non-smoking areas for PM2.5, PM1 and LDSA. 2022 a second study in 40 Viennese establishments mainly frequented by young people confirmed earlier results, but some outliers indicated, that control of compliance has to be continued.

Methods:
Sampling strategy and measurements of PM and UFP had been described before (Mattar & Neuberger. Ultrafine Particles in Viennese Gastronomy after Introduction of a National Smoking Ban. Adv Clin Toxicol 2023, 8: 264).

Results and Conclusions:
In Linz 9 of 53 measurements indicated that in these venues cigarettes and/or water pipes were still used in 2021-2022 and the indoor smoking ban had been ignored. In 2023 in Vienna we selected only enterprises which advertised shisha, found 11 for unannounced sampling and in 8 cases violation of the law by indoor smoking at the time of our visit. There we measured in room air a mean particle (>10nm) number concentration of 370,241/cm³ and a mean LDSA of 987 µm²/cm³, which indicate a health hazard. Concentrations were a magnitude higher than outdoors and increased with the number of smokers.