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Int. J. Environ. Res. Public Health 2022, 19, 16971. https://doi.org/10.3390/ijerph192416971 www.mdpi.com/journal/ijerph
Article
Evaluation of Risk Perception of Smoking after the
Implementation of California’s Tobacco 21 Law
Joanna K. Sax
1,
* and Neal Doran
2
1
California Western School of Law, 225 Cedar St., San Diego, CA 92101, USA
2
Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
* Correspondence: jsax@cwsl.edu, Tel.: +1-619-515-1555
Abstract: Decreasing smoking initiation remains a public health priority. In 2016, California, in the
United States, enacted the Tobacco 21 law, which raised the minimum age for the purchase of to-
bacco products from age 18 to age 21. This paper evaluates whether the enactment and implemen-
tation of the Tobacco 21 law changed how young adults perceive the risk(s) of smoking. Data were
drawn from a cohort of emerging adults (n = 575) in California who were non-daily smokers at
enrollment and followed quarterly for 3 years. Data were collected during 2015–2019. Piecewise
multilevel regression models were used to test for changes in smoking status and perceived risks of
cigarettes after Tobacco 21 enforcement began. Findings indicated that the prevalence of current
smoking and perceived risks of smoking both declined following Tobacco 21 implementation (ps <
0.001). Post-hoc analyses suggested that post-implementation changes in perceived risk occurred
primarily among ongoing smokers. Findings suggest that Tobacco 21 and associated public health
measures have been effective, but additional research is needed to disentangle the effects of specific
components. Understanding the impact and efficacy of tobacco laws provides great social value to
research and implement policies that create intervention(s) on reducing tobacco use initiation.
Keywords: Tobacco 21 law; smoking; risk perception; intervention; public policy; young adults
1. Introduction
In 2016, California, in the United States, enacted Senate Bill No. 7 (known as “Tobacco
21”), which raised the minimum age for sales of tobacco products from age 18 to 21 [1].
The purpose of this Tobacco 21 law was to make it more difficult for individuals under
the age of 21 to obtain cigarettes and other tobacco and nicotine-containing products [2,3].
Previous research indicates that individuals are more likely to become addicted to smok-
ing the earlier they begin [2]. Historically, the initiation of smoking primarily occurred
during adolescence, but recent data suggest that initiation is shifting to young adulthood
[4]. Thus, the Tobacco 21 law raised the minimum age for retailers to sell nicotine and
tobacco products to individuals. In conjunction with the minimum age increase, Califor-
nia launched a public awareness campaign to educate the public, support the minimum
age change in the Tobacco 21 law, and inform retailers about the change [5].
Previous studies indicate that Tobacco 21 laws can be an effective means of reducing
smoking prevalence, particularly among youth and emerging adults [6,7]. Evidence indi-
cates that such restrictions decrease the ability of individuals under 21 to purchase tobacco
products, potentially delaying or even preventing the initiation of tobacco use [8]. It has
been demonstrated that California retailers were highly aware of the law and generally
compliant with its requirements [5].
While the Tobacco 21 law appears to decrease access to tobacco products at the point
of sale for individuals under 21, it is less clear whether it impacted how young adults
perceive the risk(s) of smoking. This is an important question, given that the perceived
Citation: Sax, J.K.; Doran, N.
Evaluation of Risk Perception of
Smoking after the Implementation of
California’s Tobacco 21 Law. Int. J.
Environ. Res. Public Health 2022, 19,
16971. https://doi.org/10.3390/
ijerph192416971
Academic Editor: Paul B.
Tchounwou
Received: 28 October 2022
Accepted: 15 December 2022
Published: 17 December 2022
Publisher’s Note: MDPI stays neu-
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claims in published maps and institu-
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Copyright: © 2022 by the authors. Li-
censee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and con-
ditions of the Creative Commons At-
tribution (CC BY) license (https://cre-
ativecommons.org/licenses/by/4.0/).
Int. J. Environ. Res. Public Health 2022, 19, 16971 2 of 8
risk of smoking is inversely associated with the likelihood of initiation [9,10]. That is, if
Tobacco 21 laws increase the perceived risk in addition to reducing tobacco access for 18–
20-year-olds, they may be more likely to prevent rather than merely delay initiation. To
our knowledge, the present study is the first to examine changes in perceived risks from
smoking among young adults following the implementation of the Tobacco 21 law.
The primary goal of this study was to test two hypotheses in a sample of young adults
who had been non-daily smokers at enrollment. First, we expected that the likelihood of
current cigarette smoking would decline following Tobacco 21 implementation. Second,
we predicted that perceived risks of smoking would increase following the implementa-
tion of Tobacco 21. Secondary analyses examined associations with smoking status.
2. Materials and Methods
2.1. Participants
Participants (n = 575) were young adults enrolled in a longitudinal study of non-daily
cigarette smoking. Eligibility requirements included being aged 18–24 at baseline, smok-
ing cigarettes at least monthly for the past 6 months or more, never having been a daily
smoker, and being a California resident at the time of enrollment. A total of 52% of percent
of participants identified as male, 44% as non-Hispanic White, 18% as Asian American,
and 22% as Hispanic/Latinx. The average age at baseline was 20.4 years (SD = 1.7).
2.2. Procedure
Candidates were recruited via paid Facebook posts. If interested, they completed a
brief online eligibility screener. Eligible respondents completed a baseline assessment and
then quarterly assessments for the next 3 years, yielding a total of 13 waves of assessment.
All assessments occurred online. At annual assessment points (baseline and 1, 2, and 3
years later; hereafter annual waves), all measures were completed on a single day, and
participants were compensated with $25 gift cards. At each of the 9 waves between these
annual assessments (hereafter quarterly waves), participants completed brief daily assess-
ments for 9 consecutive days and were compensated up to $40 per wave. Data were col-
lected during 2015–2019. The study was approved by the Institutional Review Board at
the University of California, San Diego.
2.3. Measures
Demographics evaluated at baseline included self-identified sex, racial/ethnic identity,
and age. Due to small cell sizes for some groups, race/ethnicity was collapsed into 4
groups: non-Hispanic White (n = 254), Asian American (n = 102), Latinx (n = 122), and
multiple or other backgrounds (n = 96).
Cigarette use was assessed at each wave. At annual waves, a Timeline Followback
procedure [11] was used to evaluate the number of cigarettes smoked in each of the past
14 days. At quarterly waves, participants reported the number of cigarettes smoked in the
past 24 h on each of 9 consecutive days. From these raw data, we calculated a cigarette days
variable, which reflected the number of days on which cigarettes were smoked at each
wave, and a binary smoking status variable, indicating whether participants had smoked
at each wave (coded as 0 = no cigarette days, 1 = 1 or more cigarette days). Because the
maximum number of smoking days differed for annual and quarterly assessments, we
also calculated days assessed, reflecting the number of days at each wave that smoking was
assessed, for use as a covariate.
Risk perceptions were measured using the Negative Consequences subscale from the
short form of the Smoking Consequences Questionnaire [12,13], which has been validated
for use in young adult samples. The subscale includes 4 items on which participants rate
perceived health risks from cigarette smoking on a 10-point scale. The subscale had good
internal consistency in the present sample (α = 0.85). Risk perceptions were evaluated at
each annual wave and on day 9 of each quarterly wave.
Int. J. Environ. Res. Public Health 2022, 19, 16971 3 of 8
2.4. Analytic Plan
Two primary models were fit. First, a longitudinal logistic regression model using
the generalized estimating equations (GEE) approach [14] was used to evaluate post-im-
plementation change in smoking status. Second, a mixed effects longitudinal regression
model was used to evaluate post-implementation change in the perceived risk of smoking.
In light of previous reports of smoking differences between demographic groups, ra-
cial/ethnic background and gender were included as covariates in hypothesis tests [15].
Similarly, we included total cigarettes smoked in the past 2 weeks at baseline as a covari-
ate. Our primary interest was in the extent to which smoking status and the perceived risk
from cigarette smoking changed over time and in relation to the implementation of To-
bacco 21 in California.
Both models utilized a piecewise or segmented multilevel longitudinal regression
approach, which has been recommended [16] for the evaluation of policy changes. This
piecewise approach included segments for the periods before and after Tobacco 21 imple-
mentation, allowing us to compare outcomes between the two periods, as well as change
over time following implementation. Models included a binary, time-varying Tobacco 21
variable that indicated whether each measurement of perceived risk occurred before or
after implementation in June 2016. We also created a post-implementation slope variable to
evaluate change over time after implementation; for each participant, post-implementation
slope was coded as 0 for all visits prior to June 2016, 1 for the first visit after implementa-
tion, 2 for the second, and so on. Finally, we created a binary, time-varying age21 variable
that reflected whether participants were 21 years old at the time of their participation in
each wave. All analyses were conducted using Stata 15.0 (StataCorp LLP, College Station,
TX, USA) with alpha = 0.05. Analyses utilized an intent-to-treat approach, retaining par-
ticipants who were lost to follow-up without imputing missing values [17].
3. Results
3.1. Preliminary Analyses
Participants completed a total of 6032 assessments of cigarette use and risk percep-
tions; 74% of these occurred after Tobacco 21 implementation. At the participant level,
90% had at least one assessment prior to implementation, 79% had at least two, 57% had
at least three, 37% had at least four, and 8% had five. In other words, for almost all partic-
ipants, the key variables were evaluated at least once prior to implementation, and the
majority of participants reported cigarette use and perceived risk at three or more waves
prior to implementation. Attrition increased gradually over the 3-year study period, from
2% at the first baseline wave to 11% at year 1, 23% at year 2, and 37% at year 3 regarding
missing smoking status and/or risk perception data. Baseline demographic and cigarette
use characteristics are shown in Table 1.
Table 1. Demographic and clinical characteristics.
Variable M (SD), Range or Proportion
Age at baseline 20.4 (1.7), 18–24
Aged 21+ at baseline 33.9%, n = 195
Aged 21+ at year 1 63.5%, n = 365
Aged 21+ at year 2 87.2%, n = 501
% identifying as female 51.7%, n = 297
% identifying as non-Hispanic White 48.7%, n = 280
Total cigarettes, past 14 days at baseline 12.4 (17.7), 0–209
Perceived risk of smoking at baseline 19.6 (5.8), 4–28
Int. J. Environ. Res. Public Health 2022, 19, 16971 4 of 8
3.2. Hypothesis Tests: Post-Implementation Changes
The piecewise GEE model of smoking status is shown in Table 2. The time term was
not significant, indicating that smoking status was stable prior to implementation. How-
ever, the tobacco 21 (z = −2.16, p = 0.031) and post-implementation slope (z = −3.20, p = 0.001)
were both significant, and both indicated an inverse association with smoking status. That
is, current smoking was less likely after the implementation of Tobacco 21 and became
increasingly unlikely during the post-implementation period. Smoking status was not as-
sociated with sex, race/ethnicity, or whether participants were 21 or older.
Table 2. Piecewise longitudinal GEE model of smoking status overall and after Tobacco 21 imple-
mentation.
Predictor Coefficient Std Err z-Score p-Value
Days assessed 0.05 0.01 11.91 <0.001
Gender a −0.03 0.03 −1.17 0.240
Racial/ethnic identity b 0.02 0.02 0.99 0.323
Total cigarettes at baseline 0.01 0.01 3.67 <0.001
Time −0.01 0.01 −0.93 0.352
Age 21 c 0.04 0.03 1.23 0.217
Tobacco 21 d −0.08 0.04 −2.16 0.031
Post-implementation slope −0.03 0.01 −3.20 0.001
Note: a 0 = male, 1 = female; b 0 = non-Hispanic White, 1 = Hispanic or Latino, 2 = Asian American, 3
= other or multiple backgrounds; c 0 = participant was aged 18–20 at the time of assessment, 1 =
participant was aged 21 or older at the time of assessment; d 0 = assessment occurred prior to To-
bacco 21 implementation; 1 = assessment occurred after Tobacco 21 implementation.
The piecewise mixed regression model of risk perceptions is shown in Table 3. Time
was inversely associated with perceived risk from smoking (z = −3.90, p < 0.001), indicating
that perceived risk was declining during the period prior to Tobacco 21 implementation.
However, both the tobacco 21 (z = 2.80, p = 0.005) and post-implementation slope (z = 3.95,
p < 0.001) terms were positively associated with perceived risk. This indicates that partic-
ipants reported greater perceived risk from cigarette smoking after Tobacco 21 implemen-
tation compared with before and that the strength of this association was increasing over
time. Risk perceptions did not differ by race or whether participants were age 21 but were
higher among participants who identified as female, who reported heavier cigarette use
at baseline, and who smoked cigarettes more frequently.
Table 3. Piecewise longitudinal multilevel model of risk perceptions overall and after Tobacco 21
implementation.
Predictor Coefficient Std Err z-Score p-Value
Days assessed −0.11 0.03 −3.95 <0.001
Gender a 0.88 0.15 5.67 <0.001
Racial/ethnic identity b 0.02 0.09 0.27 0.789
Total cigarettes at baseline 0.04 0.01 8.02 <0.001
Time −0.23 0.06 −3.90 <0.001
Age 21 c 0.25 0.19 1.31 0.189
Cigarette days 0.16 0.03 6.10 <0.001
Tobacco 21 d 0.69 0.25 2.80 0.005
Post-implementation slope 0.24 0.06 3.95 <0.001
Note: a 0 = male, 1 = female; b 0 = non-Hispanic White, 1 = Hispanic or Latino, 2 = Asian American, 3
= other or multiple backgrounds; c 0 = participant was aged 18–20 at the time of assessment, 1 =
participant was aged 21 or older at the time of assessment; d 0 = assessment occurred prior to To-
bacco 21 implementation; 1 = assessment occurred after Tobacco 21 implementation.
Int. J. Environ. Res. Public Health 2022, 19, 16971 5 of 8
To better understand this finding, post hoc analyses examined change in perceived
risk over time during the post-implementation period as a function of smoking status (i.e.,
whether participants reported any smoking days at each individual post-implementation
wave; see Figure 1). These analyses excluded pre-implementation waves and utilized lon-
gitudinal mixed effects regression, with time-varying risk perceptions as the outcome var-
iable. For non-smokers, the perceived risk did not change over time after implementation
(z = −0.50, p = 0.615). In contrast, for those who reported continued smoking, perceived
risks from smoking increased over the course of the post-implementation waves (z = 3.48,
p = 0.001).
Figure 1. Risk perceptions over time by smoking status after Tobacco 21 implementation.
4. Discussion
This study investigated smoking status and perceived risk of cigarette smoking
among young adults before and after the statewide implementation of Tobacco 21 in Cal-
ifornia, United States. As hypothesized, we found that likelihood of smoking decreased,
and risk perception increased after the implementation of the Tobacco 21 law. We also
found that the increased perception of risk was associated with smoking status, increasing
among those who were current smokers but not those who were not.
At the time of enactment, California was among the minority of states in the United
States that adopted a Tobacco 21 law. Other states and countries have a strong interest in
preventing young adults from initiating tobacco use due to the individual health and pub-
lic health issues related to smoking. Given the experience with state-initiated Tobacco 21
laws, the United States federal government enacted its own Tobacco 21 law [18]. Under-
standing not only the efficacy of a Tobacco 21 law but the possible underlying reason(s)
for its efficacy provides great social value in engaging in effective legal interventions to
address public health issues, both as it relates to tobacco use and possibly more broadly
to address other public health issues.
Studies analyzing risk perception suggest that the more heavily regulated an indus-
try is, the higher individuals perceive the risk of that industry [19]. Thus, one possible
reason that the Tobacco 21 law was associated with an increased perception of risk is be-
cause it represented increased regulation of tobacco products. In addition, the public
awareness campaign may also have contributed to perceptions of risk.
17
17.5
18
18.5
19
19.5
20
20.5
21
21.5
22
012345678910111213
Mean Perceived Risk
Post-Implementation Wave
Non-Smokers Smokers
Int. J. Environ. Res. Public Health 2022, 19, 16971 6 of 8
Additional studies are needed to increase our understanding of factors that directly
impact perceived risk to enable the optimization of public health messaging. For example,
risk information may be perceived differently depending on the perceived authority of
the source (e.g., television news versus social media) [20]. Initial work examining message
content also suggests that because the harms of combustible tobacco are well-understood,
messages that focus on emotional content framed around loss may be more effective than
messages that focus on providing information [21].
This study suggests that the impact of restrictions may go beyond logistical barriers
by impacting attitudes toward products or activities that are regulated. This is important
because it suggests that interventions that impact the perceived risks of tobacco products
can contribute to alleviating the public health consequences of tobacco use. Clinical impli-
cations of decreasing the initiation and prevalence of smoking among young adults in-
clude a decrease in mortality and morbidity [2]. These clinical implications are not just for
the individual but also for maternal/fetal and infant outcomes if tobacco use is lowered
among young adults [2].
Legal interventions do not always obtain the desired result and/or may have trade-
offs [22]. The results of this study suggest that the Tobacco 21 law may have led to in-
creased risk perception among emerging adults who were using tobacco products. This is
potentially important for multiple reasons. First, previous studies have indicated that
greater perceived risk is associated with a lower likelihood of smoking uptake and a
greater likelihood of cessation [9,10]. Second, evidence indicates that the perceived risk of
smoking cigarettes has been declining in recent years [23], which raises concern that prev-
alence may increase. Our data suggest that Tobacco 21 laws may be an effective way to
address this issue. In addition, these findings provide insight into the potential for legal
policy interventions to align an individual’s perception of risk with the evidence-based
assessment of risk.
To our knowledge, this is the first study to demonstrate that the Tobacco 21 law ap-
pears to change risk perception. Previous studies, for example, analyzed retailer compli-
ance and point of sale to young adults, which focus on the efficacy of restricting access to
young adults [5,8]. This study goes beyond compliance to suggest that this legal policy
intervention changed attitudes toward tobacco use. Put differently, the Tobacco 21 law
appears effective not just because it made it more difficult for young adults to purchase
tobacco products but because it also changed underlying attitudes towards the risk of
smoking.
This study has several limitations. First, we did not directly evaluate factors that may
have impacted risk perceptions over time. It could be that the messaging in the public
media campaign impacted risk perception. Alternatively, other components of Tobacco
21 implementation (e.g., restricted access at the point of sale) may have been significant.
Second, all participants were young adults with a history of non-daily cigarette smoking
who were California residents at the time of enrollment. It is possible that findings are not
generalizable to other groups.
The impact of the Tobacco 21 law on the risk perception of young adults is important
both as an intervention for reducing tobacco use initiation and could have wider applica-
tion and insight in other areas in which aligning individual perception of risk with the
evidence-based assessment of risk provides great social value, such as vaccines, food, and
other public health issues.
5. Conclusions
Smoking among young adults continues despite several public health measures to
curtail smoking initiation. These data suggest that the enactment of the Tobacco 21 law
effectively and significantly changed the perception of risk among young adults, espe-
cially those who were current smokers. Despite this significant change, young adults con-
tinue to smoke; thus, future studies that aim to understand why risk perception changed
Int. J. Environ. Res. Public Health 2022, 19, 16971 7 of 8
may inform future interventions to increase the extent to which they effectively reduce
cigarette consumption.
Author Contributions: Conceptualization, J.K.S. and N.D.; methodology, N.D.; formal analysis,
N.D.; writing—original draft preparation, J.K.S. and N.D.; writing—review and editing, J.K.S. and
N.D.; funding acquisition, N.D. All authors have read and agreed to the published version of the
manuscript.
Funding: This study was funded by research grant R01 DA 037217 (ND) from the National Institutes
of Health.
Institutional Review Board Statement: The study was conducted in accordance with the Declara-
tion of Helsinki and approved by the Institutional Review Board of the University of California San
Diego (protocol code 140271; original approval on 7 July 2014; most recent approval on 4 March
2022).
Informed Consent Statement: Informed consent was obtained from all subjects involved in the
study.
Data Availability Statement: The dataset is available upon request from the second author at
nmdoran@health.ucsd.edu.
Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the
design of the study; in the collection, analyses, or interpretation of data; in the writing of the manu-
script; or in the decision to publish the results.
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