Objectives This study quantified the secondhand smoke (SHS) concentration in a sample of public places in Vietnam to determine changes in SHS levels 5 years after a public smoking ban was implemented.
Methods Two monitoring campaigns, one in 2013 (before the tobacco control law was implemented) and another in 2018 (5 years after the implementation of the law) were conducted in around 30 restaurants, cafeterias and coffee shops in major cities of Vietnam. Concentrations of PM2.5, as an indicator of SHS, were measured by portable particulate matter monitors (TSI SidePak AM510 and Air Visual Pro).
Results The geometric mean PM2.5 concentration of all monitored venues was 87.7 µg/m3 (83.7–91.9) in the first campaign and 55.2 µg/m3 (53.7–56.7) in the second campaign. Pairwise comparison showed the PM2.5 concentrations in the smoking observed area was triple and double those in the non-smoking area and the outdoor environment. After adjusting for sampling locations and times, the SHS concentration 5 years after the implementation of the tobacco control law reduced roughly 45%.
Conclusion The study results indicate an improvement in air quality in public places in Vietnam via both the reduction in PM2.5 levels and the number of people observed smoking. However, greater enforcement of the free-smoke legislation is needed to eliminate SHS in public places in Vietnam.
- low/middle income country
- public policy
- secondhand smoke
Data availability statement
Data are available on reasonable request. Data and additional information available may be requested from the author through the email: firstname.lastname@example.org or email@example.com.
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Secondhand smoke (SHS) is a human carcinogen that remains a major global public health concern. In addition to causing cancer, SHS increases the risk of cardiovascular disease, asthma, respiratory diseases and sudden infant death syndrome.1–3 The most recent global burden of disease study on comparative risk assessment estimated that SHS exposure was responsible for 23.7 (UI:18.4–29.5) million disability-adjusted life years in 2016.4
SHS is a significant source of inhalable suspended particles or PM2.5.1 5 These particles are dangerous and lead to a variety of adverse health effects, including cardiovascular disease, respiratory morbidity and death.6–8 Therefore, PM2.5 has been used as a marker to monitor SHS exposure in previous studies.9–14
In Vietnam, 15.6 million adults (22.5%; 45.3% men and 1.1% women) were recorded as tobacco smokers in 2015. To reduce tobacco smoking, Vietnam enacted the Law on Prevention and Control of Tobacco Harms (the tobacco control law) in May 2013. Article 11 of the law implements a comprehensive smoking ban in healthcare facilities, educational institutions, kindergartens, office buildings and areas with a high risk of explosion, while article 12 specifies hospitality venues allowed to have designated smoking areas, including bars, karaoke lounges, discos, hotels, ships and trains. However, the lack of strict enforcement may leave the community exposed to SHS in these venues. The latest survey on adults and tobacco in Vietnam in 2015 (Global Adult Tobacco Survey 2015) indicates that 5.9 million adult non-smokers were exposed to SHS in the workplace and 18.5% of non-smokers (1.4 million adults) were exposed to tobacco smoke while using public transport. This study aims to quantify SHS levels in hospitality venues in Vietnam before and 5 years after the implementation of the tobacco control law.
Our study included data from two sampling campaigns to measure SHS levels. The first campaign was conducted in April 2013 before the implementation of the tobacco control law (May 2013). The second campaign was conducted from April to May 2018, 5 years after the law was implemented.
In both campaigns, the data collection team (two persons) received training in the data collection procedure. The principal researcher gave a list of main streets to the data collectors who visited each street to find venues that satisfied the selection criteria: (1) a restaurant, cafeteria or coffee shop (shop serving drinks only); (2) an owner willing to participate in the study and (3) a venue at least 250 m from another qualified venue.
Campaign 1 included venues from three cities in Vietnam: Hanoi, Hai Phong and Ho Chi Minh City, which are the major commercial and social centres of Vietnam. Campaign 2 included only venues from Hanoi and Ho Chi Minh City for logistic reasons. Efforts were made to conduct the sampling in the same venues for the two campaigns. However, many venues had moved or closed down after 5 years and were replaced with similar establishments in the same suburbs. Eventually, there were only eight venues that were sampled in both campaigns.
The TSI SidePak AM510 Personal Aerosol Monitor (TSI, St. Paul, Minnesota, USA) was used for campaign 1, while the AirVisual Pro Monitor (IQ Air, Switzerland) was used in campaign 2 to monitor the concentration of PM2.5. The SidePak was fitted with a 2.5 µm impactor to measure the concentration of particulate matter less than or equal to 2.5 µm. The AirVisual Pro is a low-cost optical particle counter, measuring PM2.5, PM10, carbon dioxide, temperature and relative humidity. Consistent with previous studies,12 15–17 a calibration factor of 0.32 was applied for the PM2.5 concentration level for the Sidepak monitor. No correction factor was applied to AirVisual data as a previous calibration study indicated this is not needed for monitoring SHS, even at much higher concentration levels.18 19
In campaign 1, PM2.5 concentrations were monitored with a 1 min log interval during 40 min around the busiest time at each venue (breakfast, lunch or dinner time). Because there was only one monitor available, the first 5 min and the last 5 min of sampling time were to measure the outdoor concentration of PM2.5, while the remaining 30 min were to measure PM2.5 levels inside the venue.
In campaign 2, PM2.5 monitors were set at a 1 min log interval. To better capture the variation in PM2.5 concentrations at the venue due to smoking behaviour, each venue was monitored for 90 min around the busiest time (breakfast, lunch or dinner time). Because three monitors were available, sampling was conducted simultaneously at different sections of each venue in this campaign, including the smoking area (if available), the non-smoking area and the outside area (outdoor environment). Each monitor was placed in a central location on a table to sample air from the patrons’ breathing zone.
Other information such as the volume of each venue, the total number of people, the number of cigarettes being smoked inside the venue, information about ventilation (fans, windows open or closed, air conditioners), presence of an open kitchen and use of candles was collected using observation questionnaires in both sampling campaigns for each 15 min interval. If there was a significant physical barrier between different spaces in a venue, such as a standard doorway separating two rooms, the volume and counts were measured only in the place where the aerosol monitor was located.
Descriptive statistics including the geometric (95% CI) and arithmetic means, SD, minimum, maximum and median were generated for the PM2.5 concentration across the whole dataset and then subdivided by the type of venue and the smoking-observed area. Differences in PM2.5 concentrations were analysed by analysis of variance on the common logarithmic scale, thereby comparing geometric means and their ratios. Non-parametric tests were performed to compare the differences in the median between groups in the campaign. The active smoker density (ASD), defined as the average number of burning cigarettes per 100 m3, was also calculated for each location sampled. A significance level of 0.05 was used for all testing.
To quantify the SHS level in the two campaigns in 2013 and 2018 (the first and second session of the results), the whole dataset of each campaign was used to describe the situation of SHS level in 2013 (campaign 1) and 2018 (campaign 2). The information of the sample was listed in online supplementary table S1.
To evaluate the change in SHS concentration before and after the implementation of the tobacco control law, for consistency purposes, only venues from Hanoi and Ho Chi Minh city were used for both campaigns (excluded the venues from Hai Phong in campaign 1). At each venue, only 30 min during the busiest time was used to analyse the change in SHS (chose only 30 min out of 90 monitored minutes at each venue of campaign 2). The information used for the analysis of evaluation was listed in table 1.
In the absence of guidelines for indoor air quality particulate matter in Vietnam, comparisons with the Vietnam ambient air quality and WHO outdoor guidelines which also apply to indoor environments8 have been used to provide perspectives on the indoor air quality measured in environments in which smoking takes place.
Consent and ethical clearance
Written informed consent was obtained from all participating restaurants/coffee shops/cafeteria.
Characteristics of the venues included in the two campaigns
In 2013, a total of 32 venues were monitored in Hanoi (14), Ho Chi Minh City (10) and Hai Phong (8). In 2018, only 27 venues were included in Hanoi (16) and Ho Chi Minh City (11). Regarding the venue type, restaurants accounted for the highest percentage in both campaigns. Of the monitored venues, the number of venues with a designated separate smoking area (partial venues) was double that of venues at which smoking is prohibited (smoke-free venues) and venues with no smoking restrictions (smoking venues) (online supplementary table S1).
We observed a higher average number of customers, smokers and cigarettes smoked in campaign 2 than in campaign 1. However, when normalised to the average ASD, the mean (SD) of ASD in campaign 1 was 10.6 (5.2), which was higher than that in campaign 2 (8 (6.7)), indicating that the proportion of smokers was higher in 2013 than in 2018. The proportion of venues with ventilation and air conditioning was high in both campaigns. During the monitoring period, no other burning events (open kitchen, candles or incense), and no other types of smoking or use of similar products (water pipes, electronic cigarettes) were observed.
The SHS situation in Vietnam in 2013
In campaign 1, the median and geometric mean PM2.5 concentration of all monitored venues was 70 µg/m3 (13–996.2) and 87.7 µg/m3 (93.7–91.9). The coffee shops had the highest level of PM2.5 concentration compared with restaurants or cafeterias (p<0.05). On average, in 2013, the PM2.5 concentration level in smoking-observed areas was four times higher than that in non-smoking areas. It should be noted that the PM2.5 levels outdoors were higher than those in non-smoking areas, demonstrating the unhealthy air quality conditions in Vietnam (table 2).
In 2013, the concentration of PM2.5 in smoking venues of 185.1 µg/m3 (166.8–205.4) was higher than that in other venues. For those venues with separate smoking and non-smoking areas (partial venues), the geometric mean concentration in the smoking area was 3.2 times higher (95% CI 3.0 to 3.5) than that in the non-smoking area (figure 1).
The SHS situation in Vietnam in 2018
During campaign 2 in 2018, the median and geometric mean PM2.5 concentrations across all hospitality venues were 58 µg/m3 (1.3–934.8) and 55.2 µg/m3 (53.7–56.7), respectively. Similar to campaign 1, coffee shops had the highest concentration of PM2.5 compared with restaurants or cafeterias (p<0.05). The median and geometric mean PM2.5 concentrations in the area where smoking was observed were 69.5 µg/m3 (35–132.7) and 71.7 µg/m3 (68.8–74.63)—significantly higher than the concentrations outdoors and in non-smoking areas (p<0.0001, Kruskal-Wallis test) (table 2). It is interesting to note that the PM2.5 concentrations in the smoking area of partial venues were higher than those in smoking venues (figure 1).
All the venues in campaign 2 were monitored at multiple locations simultaneously both inside and outside each venue. We observed that the cigarette plume drifted from the smoking area to the non-smoking area in the partial venues. A significant correlation Of pm2.5 Concentration between the smoking and non-smoking areas in the partial venues was detected (spearman rank of 0.55, P<0.001). Figure 2 shows a typical example of a partial venue (venue 18) which illustrates the impact of an indoor smoking area on the non-smoking area.
The average pairwise ratio of PM2.5 concentration by the area of smoking during the 90 min monitoring period is shown in figure 3A. The concentration of PM2.5 in smoking areas was three times higher than in non-smoking areas (ranging from 1.7 to 5.5, mean (SD) of 3 [0.84]). Compared with the outdoors, the smoking areas had double the PM2.5 concentration of the outdoor environment, while the non-smoking areas had a comparable PM2.5 concentration to that of the outdoors.
In 2018, we recorded the highest concentrations of PM2.5 in smoking venues and the lowest concentrations at smoke-free venues. The partial venues (with a designated separate smoking room/area) had a similar PM2.5 concentration to the smoking venues (p=0.6). Similarly, the pairwise ratio (figure 3B) showed a lower concentration of PM2.5 in smoke-free venues compared with outdoors, while smoking venues or partial venues shared a similarly high ratio to the outdoors (average ratio (SD) partial venues: 1.5 (0.16); smoking venues: 1.6 (0.45)).
Changes in SHS levels
To evaluate the change in SHS concentrations before and after the implementation of the tobacco control law, and to maintain consistency, only venues from Hanoi and Ho Chi Minh City from both campaigns were used. At each venue included in both campaigns, a 30 min period during the busiest time was used to assess the change in SHS level. The PM2.5 concentrations measured in campaign 1 in 2013, just before the implementation of the tobacco control law, was used as the background sample (preban). PM2.5 concentrations from campaign 2 in 2018, 5 years after the implementation of the tobacco control law, were used as the postban sample (table 1).
There were no differences between the two sets of samples regarding suburb, type of venue, distribution of venues by smoking policy, ventilation system, number of customers or percentage of venues with a kitchen area open to the monitoring area. The number of smokers and the number of cigarettes smoked were higher in the preban campaign than in the post-ban campaign (p<0.05).
The geometric mean PM2.5 concentration across all venues was 93.1 µg/m3 (88.9–97.4) in the preban sample, which was significantly higher (p<0.05) than the postban value of 55.6 µg/m3 (53.1–58.2). A reduction of 45% (95% CI 42% to 48%) in geometric mean PM2.5 concentration was the result of the implementation of the tobacco control law. Regression analysis of 51 venues with adjustment for other factors, such as volume, number of customers and type of venue showed that the geometric mean concentration of PM2.5 across all monitored venues reduced by roughly 40.4 µg/m3 (p=0.01) after 5 years of implementation of the tobacco control law.
In the absence of guidelines for indoor air quality particulate matter in Vietnam, comparisons with the Vietnam ambient air quality and WHO outdoor guidelines which also apply to indoor environments8 have been used to provide perspectives on the indoor air quality measured in environments in which smoking takes place. Among the 51 venues preban and postban, a high percentage of venues exceeded the guidelines in both campaigns. Preban PM2.5 levels exceeded the Vietnam ambient air quality for 24 hours standard of 50 µg/m3 in 70.8% of the venues, and this proportion decreased slightly to 66.7% in the postban levels. However, this reduction was not significant (p=0.75). In contrast, we found that a higher proportion of venues exceeded the 24 hours standard of 25 µg/m3 of WHO guidelines in postban compared with preban; however, this difference also was not significant (p=0.56).
This study examined SHS exposure in restaurants and coffee shops which are popular public places in Vietnam. The average number of customers and smokers in both campaigns was comparable with other studies which investigated SHS levels in pubs and restaurants during busy periods.9 20 21 In both monitoring campaigns, we observed only regular cigarette smoking, and no use of alternative products (eg, vaping devices) was observed.
A geometric mean PM2.5 concentration in smoking areas of 167.5 µg/m3 (157.6–178.1) in campaign 1 was comparable to that reported 5 years earlier in 2008 (ie, 176 µg/m3 (127–244)).12 Five years after the tobacco control law was implemented, in campaign 2, we found a considerable decrease to 71.7 µg/m3 (68.8–74.63) in locations where smoking was observed. The concentration measured in campaign 2 was also lower than the concentration of PM2.5 measured in indoor environments in countries with no comprehensive clean indoor air policies, such as China, Belgium, France, Ghana, Lebanon, Malaysia,12 Greece,20 Thailand10 and Egypt,9 but much higher than those in countries with comprehensive clean indoor air policies and high compliance,12 22–24 including Ireland,23 New Zealand24 and Scotland.21 25
It is noted that the concentration of PM2.5 in non-smoking areas (the combination of smoke-free venues and designated non-smoking area in the partial venues) was higher in both campaigns compared with previous studies that reported concentrations less than 25 µg/m3.12 20 21 26 This could be due to the impact of the high PM2.5 levels from the outdoor environment. Figure 3A shows a pairwise PM2.5 ratio of 1 between non-smoking areas and the outdoor environment. This finding could also have resulted from the impact of SHS leakage from smoking areas to non-smoking areas (figure 2). A similar finding was reported by Kungskulniti et al, in which a high Spearman rank correlation of 0.79 was reported between the PM2.5 concentration in a smoking area and an adjacent non-smoking area in a Thai international airport.10 Similarly, Fu et al 27 concluded that SHS exposure penetrates to indoor smoke-free areas due to smoking occurring close to the entrance.
It is also noted that although a 20% reduction in the level of outdoor PM2.5 was observed between 2013 and 2018, it probably has little impact on the indoor environment of the studied sites because the PM2.5 concentrations in smoke-free venues were not significantly different (p>0.05) between the two campaigns (figure 1).
We found a higher concentration of PM2.5 in coffee shops in both campaigns compared with restaurants and cafeterias. This is consistent with the findings of Nguyen et al 28 who revealed that the prevalence of respondents exposed to SHS was much higher in bars/cafés/tea shops (90.07%) and restaurants (81.81%) than in any other public places in Vietnam.
In general, we found that the implementation of the tobacco control law in Vietnam resulted in a significant decrease in SHS concentration, the number of smokers and the number of cigarettes smoked in the public places covered by the law. The findings are consistent with the 2015 national survey data that showed a decreasing trend in the prevalence of tobacco smoking in Vietnam over the last 15 years.29 30 However, the reduction of 45% (95%CI 42% to 48%) found in this study was lower than seen in some other countries following the implementation of a smoke-free law, where reductions of 80%–94% have been reported.21 25 31 32 There are several possible explanations for these different results.
First, Vietnam’s smoke-free legislation in tobacco control law is only a partial ban, rather than a comprehensive ban as recommended by the WHO Framework Convention on Tobacco Control.33 34 Our findings showed a similar distribution of PM2.5 concentrations in smoking venues and partial venues (with separate indoor smoking areas). Our findings strengthen those of previous studies in other countries and demonstrate that partial bans are not as effective as comprehensive bans in reducing SHS exposure.35–38 For example, comprehensive smoke-free legislation in Greece reduced SHS by 67%, which was 37% higher than that achieved by a partial ban.14 Similarly, a comprehensive ban in Norway reduced total PM2.5 concentrations in bars and restaurants from 262 µg/m3 to 77 µg/m3 (71% reduction),31 while an 86% average reduction was reported in Scotland (246–20 µg/m3)21 In Israel, after the implementation of partial smoke-free legislation, the SHS reduced by only 34%.32
Another potential contributing factor may be weak enforcement of the law. Even the smoke-free legislation in Vietnam is a partial-ban, however, restaurants, cafeterias or coffee shops are not listed as the indoor public places that allow separated smoking areas. But in fact, we observed smoking in many restaurants, cafeterias and coffee shops that should have been smoke-free under the law. These results are consistent with survey data from a nationally representative sample of 8996 adults which found that SHS exposure remains common in many public places, and 13.2% of respondents saw smokers violate smoke-free regulations. The study also emphasised the minimal effective in SHS exposure at entertainment places which showed a slight decline proportion of SHS exposure at bar/cafés/tea shops and restaurants compared with the previous study. The SHS exposure was reported highest in bars/cafés/tea shops (90.1%), following with the restaurants (81.8%).28 39
Several limitations of this study need to be mentioned. First, we did not monitor the nicotine concentration on surfaces and relied on PM2.5 as a proxy for SHS. However, since smoking is a significant source of indoor air pollution, reducing smoking will result in a substantial decline in PM2.5 levels.40–42 During the measurement period of campaign 2, we also controlled for other sources of fine particulate matter by simultaneously monitoring different locations within the venue and the outdoor environment. Finally, this study only examined three common types of indoor public places in Vietnam (restaurants, coffee shops and cafeterias). Future studies should measure additional types of locations, such as transportation stations, bars and pubs to provide a more comprehensive picture of SHS exposure in indoor public places in Vietnam.
This is the first study to quantitatively investigate the change in SHS after the introduction of Vietnam’s tobacco control law. The results indicate an improvement in air quality in restaurants, cafeterias and coffee shops in Vietnam evidenced by the reduction in PM2.5 concentrations and the number of smokers observed. However, further improvements could be achieved with a comprehensive ban and stricter enforcement of the law.
What this paper adds
What is already known on this subject
Secondhand smoke (SHS) exposure is a substantial risk factor for human health. PM2.5 is commonly used as a marker to monitor SHS exposure in air monitoring studies.
What important gaps in knowledge exist on this topic
Only one previous study has measured SHS levels in public places in Vietnam.
There has been limited research into changes in SHS levels in public places in developing countries, especially in Vietnam, and no published evaluation of SHS levels in public places after the tobacco control law was implemented in May 2013.
What this paper adds
This is the first study to quantitatively evaluate the change in SHS levels after the implementation of the tobacco control law in Vietnam.
A reduction of 45% was found for SHS concentration 5 years after the implementation of the tobacco control law.
Partial bans are also not effective in Vietnam. Therefore, strong enforcement of the law is required to substantially reduce the level of SHS.
Data availability statement
Data are available on reasonable request. Data and additional information available may be requested from the author through the email: firstname.lastname@example.org or email@example.com.
The study protocol was reviewed and approved by the Review Board of Hanoi University of Public Health (HUPH) with decision No 259/2018/YTCC-HD3.
The authors would like to thank Tobacco Free Kids (TFK) for supporting the funding of the first campaign of this study. Long Tran is the recipient of the QUT Postgraduate Scholarship. This study was partly supported by Phong Thai’s QUT Vice Chancellor Research Fellowship grant.
Contributors LKT, LTTH and PKT designed the study; LKT and HHTCL collected the data, LKT, LTTH analysed/interpreted data; LKT, PKT, HHTCL and LM drafted the manuscript; PKT, CEG and LM provided critical review of intellectual content. All authors reviewed the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.