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Exposure to tobacco smoke before and after a partial smoking ban in prison: indoor air quality measures
  1. Catherine Ritter1,
  2. Cong Khanh Huynh2,
  3. Jean-François Etter3,
  4. Bernice S Elger1
  1. 1University Centre of Legal Medicine of Geneva and Lausanne, Geneva, Switzerland
  2. 2Institute for Work and Health (IST), Lausanne, Switzerland
  3. 3Institute of Social and Preventive Medicine, Faculty of medicine, University of Geneva, Geneva, Switzerland
  1. Correspondence to Catherine Ritter, University Center of Legal Medicine of Geneva and Lausanne, Rue Michel-Servet 1, CH-1211 Geneva, Switzerland; catherine.ritter{at}


Although exposure to secondhand smoke (SHS) is reportedly high in prison, few studies have measured this in the prison environment, and none have done so in Europe. We measured two indicators of SHS exposure (particulate matter PM10 and nicotine) in fixed locations before (2009) and after (2010) introduction of a partial smoking ban in a Swiss prison. Access to smoking cessation support was available to detainees throughout the study.

Objectives To measure SHS before and after the introduction of a partial smoking ban.

Methods Assessment of particulate matter PM10 (suspended microparticles of 10 μm) and nicotine in ambient air, collected by real-time aerosol monitor and nicotine monitoring devices.

Results The authors observed a significant improvement of nicotine concentrations in the air after the introduction of the smoking ban (before: 7.0 μg/m3, after: 2.1 μg/m3, difference 4.9 μg/m3, 95% CI for difference: 0.52 to 9.8, p=0.03) but not in particulate matter PM10 (before: 0.11 mg/m3, after: 0.06 mg/m3, difference 0.06 mg/m3, 95% CI for difference of means: −0.07 to 0.19, p=0.30).

Conclusions The partial smoking ban was followed by a decrease in nicotine concentrations in ambient air. These improvements can be attributed to the introduction of the smoking ban since no other policy change occurred during this period. Although this shows that concentrations of SHS decreased significantly, protection was still incomplete and further action is necessary to improve indoor air quality.

  • Smoking
  • prison
  • secondhand smoke
  • nicotine
  • particulate matter
  • environmental tobacco smoke

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Exposure to secondhand smoke (SHS) presents serious health risks to non-smokers, increasing their risk of heart disease and lung cancer by 25%–30%.1 There is no threshold below which exposure is risk free, and measures such as separating smokers from non-smokers and ventilation are either insufficient or impractical in most situations.2–5

Exposure to SHS is particularly high in prison because of the high smoking prevalence among detainees, overcrowding, poor ventilation and inadequate enforcement of smoking restrictions.6–11 This situation leads to general annoyance as well as health risks for both staff and detainees.12 ,13 Recently, the WHO underlined the importance of considering both staff and prisoners' needs in tobacco-related matters in prisons and stated that policies designed to protect against SHS and to encourage smoking cessation should be implemented.14 Particular consideration should be given to places that are used both as workplaces and as residences, such as prisons.5

Even though SHS is one of the most frequent causes of indoor air quality complaints and is a cause of morbidity and mortality, few studies have examined the indoor air quality in prison. To our knowledge, none has measured both common indicators of SHS exposure (ie, particulate matter and nicotine) at the same time, and no such data from European prisons is available in the peer-reviewed literature.

The aim of this study is to assess indoor air quality before and after introduction in 2009 of a partial smoking ban in a Swiss prison hosting mostly sentenced prisoners (penitentiary). We evaluate whether the ban is a sufficient measure to prevent exposure to SHS in this setting.5


The intervention evaluated in this study is the implementation of a partial smoking ban. Interviews with staff and detainees indicated that this regulation was the best suited to this specific prison setting, as a total smoking ban was deemed neither acceptable nor realistic.10 ,15 ,16 The partial smoking ban was driven by a new stricter cantonal (regional) law that prohibited smoking in enclosed working areas, implemented in November 2009.17 Since 2002, smoking cessation support was accessible to detainees who requested it. Throughout the study, cigarettes could be purchased in prison or brought in by visitors.

Almost all prisoners were sentenced, and work was both available and mandatory for all detainees (indoors or outdoors within the prison grounds). Living units were blocks of 20 individual cells, with a large common room for meals, television and play. Except for two closed units, detainees were allowed to move relatively freely indoors and outdoors during the day, depending on their work assignment. At night, detainees were locked in individual cells.

Before the introduction of the partial smoking ban, smoking was permitted throughout the facility, with numerous exceptions. In some working areas (eg, woodwork areas), the regulation was actually less prohibitive than in comparable areas outside the prison. Other areas, on the other hand, were already smoke-free prior to the implementation of the smoking ban: the medical unit, the administrative building, the educational and food processing areas, and the kitchen and the community living room during meal times (30 min at lunch time and dinner time) (see table 1). After the ban, smoking was still permitted only in cells and in some designated outdoor areas.

Table 1

Sampling locations with corresponding smoking regulations before the introduction of a partial smoking ban (all locations became smoke free after the ban) and indicators measured in a Swiss prison

We used two indicators to assess indoor air quality 2 months before (September 2009) and 11 months after the ban (October 2010):

  • Particulate matter PM10 assessed with SidePark monitors (DataRAM PDR) placed in three different locations, chosen because they were exposed to various environmental particles other than SHS. Those aerosol monitors measured the particles in real time during a 4-day period before the ban and a 7-day period after the ban.

  • Nicotine concentrations in the ambient air, assessed with a passive sampling device called Monitor of Nicotine constructed by, and validated at, the laboratory of the Institute of Occupational Health (Lausanne, Switzerland).18 These devices were placed in 10 different locations for 7 days.

Both nicotine and particulate matter PM10 were measured in three locations. In seven others, nicotine only was measured. The detectors were placed in exactly the same locations before and after the smoking ban (see table 1). Control values were measured locally outdoors.


All comparisons are based on concentrations over 24 h period calculated on the average 4- or 7-day results. Paired t tests were used to compare particulate matter PM10 and nicotine concentrations at all locations before and after the ban.


Particulate matter PM10

Concentrations of particulate matter PM10 before and after the smoking ban are presented in table 2 and figure 1.

Table 2

Particulate matter PM10 concentrations before and after the introduction of a partial smoking ban in a Swiss prison

Figure 1

PM10 concentrations (milligrams per cube metre) before and after a partial smoking ban in a Swiss prison. Box and whisker plots display means, 5th/95th percentiles and minimum/maximum values for PM10 concentrations in three sites.

Nicotine concentrations

Nicotine concentrations before and after the smoking ban are presented in table 3 and figure 2.

Table 3

Nicotine concentrations before and after the introduction of a partial smoking ban in a Swiss prison

Figure 2

Nicotine concentrations (micrograms per cube metre) before and after a partial smoking ban in a Swiss prison. Box and whisker plots display means, 5th/95th percentiles and minimum/maximum values for nicotine concentrations in 10 sites.


SHS after implementation of the partial smoking ban

Nicotine concentrations decreased significantly after the smoking ban was implemented, in contrast with a non-significant change in particulate matter PM10. This apparent inconsistency is possibly due to the fact that nicotine has been shown to be a more selective tracer for SHS, whereas particulate matter is unspecific.1 ,19 Another explanation might be the smaller sample available for PM10 detection with only three rather than 10 sites of measurement. Nonetheless, real-time measures provided some insight into smoking habits, by showing a peak in particulate matter concentration almost at the same time both before (at 12:32) and after the ban (at 12:39). The partial smoking ban did not change smoking habits at lunch time but the locations where people smoked, that is, either outdoors or in the cells, but no longer in the common living room.

After the ban, indoor nicotine values (mean concentration 2.1 μg/m3) remained 10 times as high as the locally comparative value measured outdoors (below the limit of detection 0.2 μg/m3) and PM10 (mean concentration 0.06 mg/m3) three times higher as the locally comparative value measured outdoors (0.02 mg/m3), indicating that the protection provided by the ban was not optimal.

Protection also remained incomplete in the occupational unit after the ban. Although there was a wood sanding post in this area, the results after the ban indicate that nicotine was still most probably the main air pollution component. Nicotine was detectable even though this wood sanding post was put closer to a window (between the two measurements) in order to offer a natural ventilation system and diminish the impact of this pollution source, which suggests that detainees continued to smoke in spite of the ban.

As expected, the most important changes in nicotine concentrations were observed in areas that became smoke-free after the ban: the common living room in the open living unit, the occupational work unit, the mechanic work area, the snooker room and the cafeteria. These differences were statistically significant, but nicotine was nonetheless still detected. This could be explained either by the fact that the ban was only partially respected in some sites or possibly by architectural reasons: even if detainees smoked only in their cells, as requested and permitted by the ban, isolation was incomplete when cell doors were closed (due to gaps underneath cell doors). Detainees might also have kept their cell doors open or failed to extinguish their cigarettes when leaving their cells for another part of the building.

The SHS indicators used in this study have their advantages and limits. PM10 concentrations illustrate the real-time evolution during the course of a day or over several days in one specific site and show at what time more attention is needed in order to improve protection against SHS, but the monitor is a visible instrument and implies a risk of manipulation or destruction. Another drawback of PM10 measures is their principle of detection that is based on the light scattering, which gives less selective response to SHS than nicotine. In contrast, nicotine passive samplers are discrete and easily hidden, which favours valid results.

Where was exposure to SHS most prominent before the partial smoking ban?

Before the smoking ban, SHS was most prominent in the common living room of the open living unit, the occupational work unit, the mechanic work area, the snooker room and the cafeteria. These were also the places where the most significant changes were expected, which our findings confirmed.

Our measures indicated that the regulation requiring a smoking ban was respected in the farmers' break room and the security staff room. In the common living room (either closed or open unit), smoking was not allowed during meal times. The peak values for particulate matter were observed just after lunch time, which indicated that the rules were respected in the areas where the measurements were conducted.


In this particular prison setting, the smoking ban extended smoke-free areas to all common rooms and smoking was permitted only outdoors or in the cells. As this was the only change in smoking policy implemented during the study, changes observed can reasonably be attributed to the smoking ban.

Our results showed a great improvement in nicotine concentrations but no statistically significant change in particulate matter concentrations after the introduction of a partial smoking ban. As such, the ban did not ensure sufficient protection against SHS. These findings are consistent with previous reports, where measures of exposure to SHS before and after a smoking ban in prisons showed significant reductions in smoke concentrations, without altogether eliminating exposure to smoke.3 ,8 This remains problematic because non-smoking detainees remain frequently exposed to SHS, without having control over their exposure. Staff protection, when they must enter cells where smoking is still allowed, is also incomplete and should be considered in the policy.20

A partial ban in a setting where prisoners can move freely from their cells to other buildings is a regulation that respects a parallel between the prisoners' rights and the rights of citizens outside the prison (ie, smoking is permitted in private homes but not in public enclosed rooms). Nonetheless, the suboptimal decline in particulate matter and nicotine measures after the introduction of a partial smoking ban in a Swiss prison indicates that (1) this ban was not fully respected or enforced and (2) the communication between cells and shared rooms leads to inevitable air contamination.

What this paper adds

  • It is known from previous studies measuring secondhand smoke in US prisons that the introduction of smoking bans improved significantly indoor air quality. No comparative European data is available in the peer-reviewed literature.

  • This study measured secondhand smoke, both particulate matter and nicotine, at the same time in European prisons.

  • Nicotine concentrations in ambient air decreased significantly after introduction of a smoking ban in a Swiss prison but still remained detectable.

  • Results suggest that with the partial ban, non-smokers (both staff and detainees) are still exposed to secondhand smoke.

  • A partial ban is an insufficient protection measure in this setting.

  • This is due to architectural reasons and insufficient enforcement of the ban.


We thank the prison administrators for participating and facilitating the study.



  • Funding Swiss Federal Office of Public Health (Tobacco Prevention Fund).

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the research project was presented to the ethical commissions of Bern where the study took place and formally accepted. Parts of the study involved patients but not the results that are presented in this submission.

  • Provenance and peer review Not commissioned; externally peer reviewed.