A third and final coding guide was applied to the full list of apps. Of note, the coding guide was clarified so that apps referencing heat-not-burn were coded as vaping-related. While tobacco heat-not-burn devices are considered distinct from vaping devices, heat-not-burn of cannabis flower is often considered vaping, and neither involves combustion. Additionally, the group could not determine the purpose of 6 apps from the Google Play Store descriptions. These apps were downloaded and evaluated using additional information from the downloaded app itself. The final 8 purpose categories were do-it-yourself coils, DIY e-liquids, shopping, entertainment, social, device, quitting smoking, and quitting vaping. Summary percentages and means for app metadata and purposes were calculated. Next, apps within each of the 8 purpose categories were ranked by total number of installs, and the top 2 to 5 apps per category were downloaded for review. Instead of ranking the most popular apps, we ranked apps by popularity within categories, so that apps with less overall popularity but potentially important purposes would be included. The number of apps selected per category varied due to ties in the reported number of installs. Because apps could have multiple categories, this procedure resulted in a list of 18 apps with 10 to 1 million downloads each. Three of these apps disappeared from the store before they could be downloaded for review; one could be replaced with a premium version of the same app. A total of 16 apps were downloaded onto 2 Samsung Galaxy Tab A tablets and a Google Pixel 2 smartphone. A random selection was reviewed by all 3 investigators. Discrepancies were discussed, and the coding guide was updated.
The final coding guide included evaluations of whether the content of the downloaded app matched the purpose category and whether it had the following types of information : information about harms of vaping ,mobile grow system information about safer vaping or DIY device use , and information about harms of smoking . For apps coded as being intended for quitting smoking or quitting vaping, the presence of a tracking feature in the downloaded app was noted . For apps coded as pairing with devices, the presence of features for tracking temperature, dosage, or device locking was noted.Finally, the Mobile App Rating Scale was applied to all 16 downloaded apps. The MARS is 23-item multidimensional measure for rating the quality of mobile health apps, with 5 sub-scales in the areas of engagement , functionality , aesthetics , information , and subjective rating. Subjective rating was not applied as these items involve hypothetical personal use. Each item was rated on a scale of 1 to 5, and ratings that differed by more than 2 points between investigators were discussed. Investigators could adjust their ratings after discussion before averaging scores and did so 7 times across the 5 discussed apps. Some information items were rated as not applicable and were excluded from average score calculations. For example, the item about meeting goals would be rated as N/A if the app purpose was not related to quitting smoking or vaping, and the visual information item would be rated as N/A if the app only contained text. Other smaller discrepancies were averaged without further discussion. Average ratings were calculated for each of the 4 sub-scales and then averaged across the 3 investigator ratings. A final score was averaged for all downloaded apps and within each category.The majority of downloaded apps matched the descriptions in the app store .
The exceptions were that 1 app coded as having quitting smoking features did not have any such features, and 1 app that was coded as not having shopping features did, in fact, have links to shopping through the app. Few apps had information about harms of vaping , safer vaping , or harms of smoking . When they did have such information, it was often difficult to find. Of note, 2 of the entertainment apps had a feature where an avatar would cough when vaping too much, which may normalize moderation in vaping; 5 apps had tracking features, which mainly recorded days passed since a user-provided quit-smoking date; and 2 of the apps with tracking features also displayed money saved and health benefits. Both device apps appeared to have temperature controls, but did not have dosage or locking settings visible, though these may have become apparent once paired with a device. Overall, the 16 downloaded apps had a mean MARS score of 3.63, with a highest mean sub-score for functionality and lowest mean sub-score for engagement . Within the sub-types of purposes, the highest mean MARS scores were for social, shopping, and device apps, and the lowest mean scores were for the quitting smoking and DIY coils apps. This study examined the content of the first 100 mobile apps on the Google Play Store using vaping and vape as search terms 1 month after Apple’s ban on vaping-related apps, which was enacted in response to concerns about youth nicotine vaping and EVALI . Of 79 apps determined to be related to vaping, over half were related to nicotine, while only a few were for cannabis, and the rest were unclear in intended substance. The most popular app content, with respect to both number of installations and percentage of these 79 vaping apps, was creating DIY liquids and DIY coils , with 20% in both categories . This may reflect a strong interest in DIY hobbies in vaping culture. DIY may allow users to control the customization process, play with novelty, save money, and achieve higher nicotine concentrations. Overall, the main purposes of the majority of these vaping-related apps on the Google Play Store were to help people continue to vape nicotine. Apps that had features to support quitting smoking or vaping were relatively rare .
Most apps that supported smoking cessation encouraged users to quit smoking by switching to vaping. These apps also contained other features to promote or facilitate vaping, such as e-liquid recipes. The 2 apps for quitting vaping that were downloaded had above average MARS scores but relatively few installations, while the 3 apps for quitting smoking that were downloaded had below average MARS scores and low sub-scores on aesthetics and information. This points to the need for apps to promote vaping cessation using evidence-based behavior-change information and strategies, along with engaging usable interfaces. There were also few apps that paired with devices , and these device apps were mainly for cannabis. Devices that pair with apps using Bluetooth technology are more expensive, which may explain their lower popularity in terms of installs. Features available in the downloaded device apps indicated that the user could control temperature, which may limit throat and lung damage, but not dosage, and there were no locking controls for users with children or those wishing to moderate their use. Given current concerns about youth vaping, the findings that over half the apps had no age controls and that a large proportion of apps without age controls was in the DIY categories are especially concerning. A smaller proportion of entertainment apps had no age controls , though many of the apps with age controls were set at Teen. Age controls may allow parents who utilize family controls to restrict their children’s access to these apps. Of the popular apps that were downloaded and reviewed in-depth, few apps presented information about the harms of vaping or smoking or included information about safer vaping. Information about harms of smoking consisted of articles comparing the harms of smoking to vaping. One app had a widget for tracking “days without smoking” that included “gained days of life” and “avoided radiographs” calculations. Information presented about harms of vaping included acknowledgments of the importance of moderating nicotine intake, the addictiveness of nicotine, or harms of vaping in front of children. The 2 downloaded apps that were intended to help people quit vaping both included links to news stories about young adults with EVALI and articles about concerns with youth vaping and the intentions of vaping companies. Safer vaping information included recommendations about coil and battery materials, causes of e-cigarette explosions, and cautions against mixing e-liquids incorrectly. It should be noted that in 2 entertainment apps with simulated vaping games, the vaping avatar would cough audibly when they “inhaled” a large amount of vapor,mobile vertical rack which could be seen as encouraging moderation in use. Several of these apps included a tracking feature that displayed the number of days since quitting smoking and the number of cigarettes avoided. Self-monitoring is an important component of a smoking cessation plan but is likely insufficient by itself. In addition to a need for apps on the Google Play store that assist people with quitting vaping, study results indicate a need for informational apps to better describe the pros and cons of vaping.
Assuming that these Google Play Store apps were similar in content to the Apple App Store apps that were removed, it appears that Apple’s ban would have had a minimal effect on people who vape with the intention of quitting smoking or who are seeking information about safer vaping. Nevertheless, the decision to remove the vaping-related apps appears to have been taken by Apple in response to rising EVALI cases, which were primarily attributed to cannabis oil additives, rather than nicotine liquids. There appeared to be little publicly available information detailing how apps were determined to be removed, echoing other calls for increased transparency and additional research regarding allowed app platform content and other issues like privacy. Future research should explore other cases touching on the who and how of regulation of apps related to controversial health-behavior for which there is not yet a consensus among health experts. Future research should also examine more explicitly the relationship between vaping app use and vaping behaviors. There were several limitations to this study. First, not all apps that came up in the initial search were reviewed, though most app users would likely not browse more than 100 apps without refining their search. Additionally, the app store gets updated continuously, and a search on a different date may present different results. Indeed, several apps were no longer available a few weeks after the initial search. While the number of installations was recorded for each as a signal of popularity, people may download an app and not use it at all or only use it a limited number of times. Only 1 of the reviewed apps was also available on the iPhone App Store, but it is unclear which of the apps we reviewed were removed from or denied approval in the Apple App Store. Although we only coded Google Play Store apps, a search for vaping in the mobile Apple App Store in December 2019 confirmed that the remaining apps were related to quitting smoking or quitting vaping or were unrelated to vaping behavior. Based on this review of vaping-related apps in the Google Play Store, it appears that the Apple vaping app ban would have had a minimal effect on adults seeking to switch away from smoking or seeking to vape more safely. Most vaping-related apps in the Google Play Store were for purposes related to continuing vaping and had limited age-based access restrictions. Few apps were for controlling device settings, assisting with quitting smoking or vaping, or disseminating information about safer vaping. In the US, as of March 2018, medical use of marijuana is legal in 28 states and the District of Columbia and recreational use is legal in 8 states and the District of Columbia. The liberalization of marijuana laws raises public health concerns, particularly about possible effects on adolescents’ marijuana use and problems. Despite potential risks, the 2016 Monitoring the Future survey shows that 36% of 12th graders and 24% of 10th graders reported past year marijuana use and 23% and 14%, respectively, reported past 30 day use. About 81% of 12th graders and 64% of 10th graders reported that marijuana is “fairly easy” or “very easy” to get. Only 31% of 12th graders and 44% of 10th graders perceived “great risk” in regular marijuana use. Commercialization of cannabis, including marijuana, concentrates, and edibles, may affect adolescents’ use directly by increasing availability or indirectly by promoting beliefs that its use is safe and normative. Although legal sales of recreational marijuana are restricted to adults, enforcement compliance checks indicate that between 11%-23% of recreational outlets may sell to minors.