From Smoking-Permitted to Smokefree Prisons: A 3-Year Evaluation of the Changes in Occupational Exposure to Second-Hand Smoke Across a National Prison System.

Objectives: Prisons in Scotland were one of the few workplaces exempt from the 2006 comprehensive smoking ban in indoor public places, excluding the prison workforce from the health benefits of smokefree workplaces. The November 2018 introduction of comprehensive restrictions on smoking in Scottish prisons aimed to protect prison staff and people in custody from the harmful impacts of second-hand smoke (SHS) exposure. This study presents SHS exposure data gathered after smokefree policy implementation and compares these with data gathered during and before policy development.

Methods: Dylos DC1700 monitors were used to measure concentrations of fine particulate matter (PM2.5) derived from SHS across Scotland's 15 prisons. Six days of fixed-site monitoring (09.00 22 May 2019 to 09.00 28 May 2019) were conducted in residential halls in each prison 6 months post-smokefree policy implementation. Prison staff task-based measurements were conducted to assess concentrations of SHS in various locations (e.g. gyms and workshops) and during specific activities (e.g. cell searches, maintenance, and meal service). Utilizing the fixed-site monitoring data, typical daily PM2.5 exposure profiles were constructed for the prison service and time-weighted average (TWA) exposure concentrations were estimated for the typical shift patterns of residential staff pre- and post-smokefree policy implementation. Staff perceptions of changes to SHS exposure were assessed using online surveys.

Results: Analysis of both fixed-site and mobile task-based PM2.5 measurements showed the smokefree policy implementation was successful in reducing SHS exposures across the Scottish prison estate. Measured PM2.5 in residential halls declined markedly; median fixed-site concentrations reduced by more than 91% compared with measures in 2016 before policy announcement. The changes in the TWA concentrations across shifts (over 90% decrease across all shifts) and task-based measurements (89% average decrease for high-exposure tasks) provide evidence that prison staff exposure to SHS has significantly reduced. Following smokefree policy implementation, the majority of staff reported no longer being exposed to SHS at work.

Conclusions: To our knowledge, this is the first comprehensive international study to objectively measure SHS levels before, during, and after implementation of a smokefree policy across a country's prison system. The findings confirm that such a policy change can be successfully implemented to eliminate occupational exposures to SHS. The results are highly relevant for other jurisdictions considering changes to prison smoking legislation.