BACKGROUND-AIM:
Second-hand smoke (SHS) is associated with adverse health effects. Many countries have extended smoke-free policies to public buildings and workplaces, including hospitals. However, mental health units have often been exempted from complete smoke-free bans. The Spanish Tobacco Law 42/2010, implemented in 2011, banned smoking in short-stay mental health units both indoors and outdoors, while maintaining exceptions in medium- and long-term units. The aims of this study are: 1) to assess the effectiveness of Law 42/2010 in reducing SHS exposure in mental health units and the estimated avoidable mortality burden associated, and 2) to describe patients’ and staff’s perceptions of the ban and their smoking prevalence.

METHODS:
A repeated cross-sectional study was conducted in 2010 and 2022 in all mental health wards in Catalonia (2010: n=64; 2022: n=68). Air concentrations of particulate matter <2.5 μm (PM_(2.5)), a marker of SHS exposure, were measured in a minimum of 4 locations within wards. A brief questionnaire was administered to patients (2010: n=600; 2022: n=744) and staff (2010: n=575; 2022: n=462) to assess their opinions about the tobacco law and their tobacco use. We also estimated avoidable mortality burden due to the law implementation using WHO-recommended PM_(2.5) risk functions.

RESULTS:
PM_(2.5) concentrations decreased markedly in 2022 compared to 2010: from 14.0 to 1.6 μg/m³ in acute units, from 36.0 to 2.2 μg/m³ in medium- and long-stay units, from 15.7 to 0.9 μg/m³ in detoxification and dual disorder units, and from 20.3 to 1.0 μg/m³ in mixed units (all p values <0.05). In 2010, 78.8% of staff members were exposed to PM_(2.5) levels above the WHO-recommended limit value of 10 ug/m³ compared with 3.8% in 2022 (p<0.05). Only half of the staff supported total smoking bans, with no significant changes between 2010 and 2020. In contrast, support among short-stay patients increased significantly (16.8% vs 34.0%, respectively; p<0.05). Smoking prevalence among patients significantly decreased (74.4% to 66.2%; p=0.003), whereas staff smoking prevalence remained unchanged (32.3% to 31.9%). Finally, the smoke-free legislation was estimated to prevent 20% of deaths among active workers between both years.

CONCLUSIONS:
The Spanish Tobacco Law substantially improved air quality in mental health wards in Catalonia during the studied period, contributing to meaningful health improvement for both patients and staff. Our findings suggest that the legislation has considerably reduced mortality attributable to SHS exposure. However, further efforts are needed to strengthen staff support for smoke-free policies and to expand their access to cessation services, given their persistently high smoking rates.