In 2020, brick-and-mortar retailers (including vape and smoke shops) accounted for >80% of the e-cigarette market share globally [1]. Initially, vape shops were critical drivers of e-cigarette uptake, enabling users to sample products before purchasing [1], which was particularly relevant given the popularity of modular devices (that allow customization in nicotine levels, flavors, etc.) [1,2] and the increasing trend of users/retailers mixing their own e-liquid and/or circumventing flavor restrictions by combining flavored zero-nicotine liquid with nicotine concentrates [1].

Before the pandemic, and perhaps in response to FDA regulation and e-cigarette sales restrictions, vape shops were twice as likely as smoke shops to close from 2018 to 2019 [73]. In response, vape shops introduced other tobacco products and a variety of un- or under-regulated cannabis and delta-8 products [73,74,75].

For users who historically accessed e-cigarettes at vape shops, stores that transitioned to selling other tobacco represent a greater exposure to the marketing and availability of such products. Prior research indicates that the exposure to tobacco products, marketing, and retail undermines smoking cessation efforts [76,77]. Given that many people use e-cigarettes to try to quit smoking cigarettes or maintain abstinence from cigarettes, this is a major concern [31,78]. In fact, one study documented that among current e-cigarette users in the US surveyed in 2014 (N = 879) and 2016 (N = 743), a greater proportion of vape shop (40.2%) and internet customers (35.1%) versus retail (17.7%) and smoke shop customers (19.3%, p < 0.001) were former smokers [79]. Moreover, among those smoking a year ago, smoking cessation rates were higher for vape shop (22.2%) and internet customers (22.5%) than for retail customers (10.7%) and smoke shops (9.4%), and the proportion making a quit attempt was the lowest among smoke shop customers (50.6%) when compared to other groups, particularly vape shops (66.4%) [79].

Those going to smoke shops also are exposed to a greater variety of other products, in particular cannabis-based products. Policies and regulations enacted in the past decade have made many such products more accessible. For example, cannabidiol (CBD) products have increased in popularity and product diversity in recent years [80], since the Agriculture Improvement Act of 2018 [81] allowed for CBD derived from hemp (cannabis and cannabis derivatives with ≤0.3% delta-9-THC) to be legally purchased in most states. Further, 15 states and DC have legalized non-medical cannabis use for adults ≥21 [82]—this is notable here given increases in vaping cannabis [83] and vaping-related lung injury particularly connected to THC [84]. These products have been more prominent in smoke shops versus vape shops. For example, 6% of vape shops and 47% of smoke shops sold CBD and/or THC products in New Hampshire in 2017 [29]. Audits of vape shops in six US metropolitan areas indicated that 43% of vape shops sold CBD e-liquids and 23% sold other CBD products in 2018 [45]. Moreover, many vape shop owners show interest in the CBD/THC product sales [75] and increasingly brand their stores with cannabis-related terms (e.g., “haze”, “toke”) [73].

Compounding these concerns is that smoke shops provide access to unregulated cannabis-based products, such as delta-8-THC (see Figure 1) [85]. Delta-8-THC has a nearly identical chemical structure to delta-9-THC (the primary psychoactive agent in cannabis) and produces a similar “high” [86]. Most cannabis strains produce minimal amounts of delta-8-THC, but larger quantities can be synthesized by chemically converting CBD (including hemp-based CBD) to delta-8-THC, delta-9-THC, and other variants (see Figure 1) [86]. Evidence is limited regarding whether toxic or otherwise harmful substances are produced as byproducts in the conversion process, raising concerns about health implications [86]. This has led some jurisdictions, such as Colorado, to prohibit these conversion methods despite the legal recreational use of delta-9-THC [86,87]. In August 2020, the US Drug Enforcement Agency (DEA) declared that any processes that create delta-9-THC as a byproduct are in violation of federal law [88], although the extent to which DEA will act on this is unclear. This lack of clarity regarding the legal status of delta-8-THC has opened to door to opportunistic manufacturers [86], For example, while US states that permit recreational cannabis use require products to be sold by licensed dispensaries, many manufacturers sell bulk quantities of delta-8-THC and pre-mixed products that resemble cannabis products directly through their websites, and some also ship their products wholesale to retailers, particularly smoke shops [86]. Among the major concerns regarding these under-regulated product are their contents; one study documented that of 27 delta-8-THC products from 10 brands, none had accurate delta-8-THC labeling, which has significant implications for consumer safety [89].

Another under-regulated product frequently found in smoke shops is kratom (see Figure 1). Kratom is derived from the leaves of a tree native to Southeast Asia. In the US, kratom is typically sold in pill, powder, and liquid forms that can be easily dissolved or consumed with food [90] and is primarily marketed as an herbal medicine/supplement to treat a variety of ailments (pain, mental health, opioid withdrawal symptoms) as well as a “legal” or “natural” high and alternative to traditional opioids (e.g., “herbal speedball”) [90,91,92,93,94]. Kratom is sold through various brick-and-mortar retailers, particularly in smoke shops [90,91,92,93,94]. Although it has been available in the US for at least a decade, it has received greater public attention since the Centers for Disease Control and Prevention (CDC) reported a significant increase in kratom-related calls to poison control centers between 2011 and 2015 [95]. Among the 660 reported calls, 49 (7.4%) were classified as major, life-threatening events with some residual disability [95]. Moreover, given the mostly unregulated market for kratom products in Western countries, consumers may be exposed to adulterated or contaminated products, especially if purchased through websites or the darknet [96]. A number of countries have scheduled kratom because of its stimulant- and opioid-like effects and the established interaction of the alkaloid mitragynine with opioid receptors [96].

Delta-8-THC and kratom are just two categories of products that have emerged and been particularly prominent in smoke shops. Among others that have made a presence are “whippits”, Noz, and N2O—which contain nitrous oxide to be recreationally inhaled to achieve a high. These products are so readily available because some state laws (e.g., California) allow their sale to those older than 18, and/or allow sales intended for culinary and automotive use (see Figure 1). However, smoke shops have been selling these products for years [97]. These products represent just a few products represented at smoke shops—not seen at vape shops in general—and this list will likely grow.

Another major concern is youth access to products at smoke shops. An analysis of 2013–2014 PATH data indicated that, among youth, the most commonly reported source for e-cigarettes and hookah was smoke shops (49.8 and 51.3%, respectively) [98]. The most common ways of accessing other tobacco products were largely from social sources or convenience stores/gas stations [98]. Moreover, another study indicated that young adult e-cigarette users (ages 18–24) represented 3.2% of those who most frequently purchased products at vape shops, but a much larger proportion (12.9%) of those who most frequently purchased products at smoke shops [79]. One likely factor determining where youth access products via retailers is retailer compliance with age verification policies, as prior research indicates that, across 2016–2018, only ~25% of youth users who tried to buy tobacco products were refused sale because of age [99]. Although FDA regulation requires retailers to check ID for all persons ≤27 years old, one study found that 49.8% of tobacco and vape shops failed to check ID for underaged decoys, a higher rate of noncompliance than for other types of retailers [62]. While one study of FDA inspection data in four states from 2017 to 2019 indicated no differences between vape vs. smoke shops in age verification compliance [100], 2019 data from California indicated noncompliance rates of 13.4% in vape shops vs. 30.6% in smoke shops [57]. Moreover, surveillance of smoke shop promotional materials have identified fliers indicating “Back to School” specials that clearly target youth (see Figure 2).