Peer-reviewed research behind every choice in Harb: what we left out, why the ritual matters, and what vaping does to your body.
Environmental Health Perspectives
Johns Hopkins tested devices from 56 daily vapers. Lead, nickel, chromium and manganese rose once the liquid touched the heating coil, and almost half of aerosol samples exceeded the EPA health-based limit for lead. Harb has no coil.
Read studyNew England Journal of Medicine
When e-liquid was heated at high voltage, it formed formaldehyde-releasing compounds. The carcinogen is created by the heat itself. Nothing in Harb gets warm.
Read studyNicotine & Tobacco Research
Raising battery voltage from 3.2 to 4.8 V increased formaldehyde, acetaldehyde and acetone in vapour anywhere from 4 to over 200 times. Heat turns ordinary solvents into toxicants.
Read studyEnvironmental Science & Technology
Berkeley Lab identified 31 harmful compounds in vapour, including two probable carcinogens, formed when propylene glycol and glycerin break down on a hot coil. Harb uses neither.
Read studyTobacco Control
Vapour from 12 e-cigarette brands contained formaldehyde, acetaldehyde, acrolein, nitrosamines and metals. Lower than cigarette smoke, but not zero.
Read studyEnvironmental Health Perspectives
Harvard found diacetyl, the flavouring linked to popcorn lung, in 39 of 51 sweet and fruity e-liquids. At least one of three related chemicals turned up in 47 of 51.
Read studyNew England Journal of Medicine
Vitamin E acetate was found in the lung fluid of 48 of 51 patients with vaping lung injury across 16 states, and in none of 99 healthy people. Most cases involved THC vapes.
Read studyAmerican Journal of Respiratory and Critical Care Medicine
Sputum from regular vapers showed raised markers of neutrophil activation and altered mucus secretion. Some changes matched smokers, others were unique to vaping.
Read studyNew England Journal of Medicine
840 smokers over six weeks: those given very-low-nicotine cigarettes smoked fewer per day and showed lower nicotine dependence. Take the nicotine out and the pull weakens.
Read studyNew England Journal of Medicine
Landmark review of how nicotine acts on the brain's reward pathways to create dependence and withdrawal. Every Harb core contains 0 mg.
Read reviewEuropean Respiratory Journal
Randomised trial of 120 smokers. Overall quit rates were similar, but among smokers with strong hand-to-mouth habits, 66.7% of those given a nicotine-free inhalator quit, versus 19.2% without one.
Read studyJournal of Abnormal Psychology
232 smokers at peak craving. Sniffing a pleasant scent cut urges by 19.3 points on a 100-point scale, versus 11.2 with no scent.
Read studyDrug and Alcohol Dependence
48 smokers after overnight abstinence. Drawing on black pepper vapour reduced craving compared with menthol or an empty inhaler, and eased anxiety symptoms.
Read studyChest
Double-blind trial of 100 smokers on nicotine patches. Adding an inhaler that recreates the throat sensation lifted 10-week abstinence to 19.5%, versus 6.8% on placebo.
Read studyDrug and Alcohol Dependence
74 smokers used a throat-sensation inhaler whenever an urge hit. It eased craving and low mood, and improved abstinence among heavier smokers.
Read studyDrug and Alcohol Dependence
How satisfying smokers found a nicotine-free aerosol was highly correlated with how strong its throat sensation was. The catch in the throat is part of the reward.
Read studyPharmacology Biochemistry and Behavior
With the airway numbed by a local anaesthetic, smoke stopped relieving craving in the moment. The throat sensation itself delivers the immediate relief.
Read studyPharmacology Biochemistry and Behavior
Nicotine-free cigarettes reduced craving and were rated satisfying. Nicotine given by IV, without the ritual, gave no satisfaction at all.
Read studyAddiction
Nicotine-free cigarettes, all ritual and no drug, suppressed several withdrawal symptoms including urges to smoke.
Read studyJournal of Substance Use
58 students randomised to black pepper oil, angelica oil or a sunflower-oil placebo. Craving scores fell after inhaling either plant oil.
Read studyJournal of Alternative and Complementary Medicine
Small campus comparison study: smokers who inhaled black pepper or angelica oil when a craving hit reported lower craving afterwards.
Read studyNature
Identified TRPM8, the receptor menthol switches on. It is why mint feels icy in the throat, and how a plant can deliver a catch without nicotine.
Read studyNeuron
Showed that cinnamon's cinnamaldehyde and other pungent plant compounds activate TRPA1, the receptor behind a warm, prickly bite.
Read studyCarcinogenesis
Australian review of 116 papers across human, animal and cell studies. Conclusion: nicotine e-cigarettes are likely to cause lung and oral cancer in people who use them.
Read reviewAmerican Journal of Respiratory and Critical Care Medicine
Young adults aged 18 to 24 who vaped had 51% higher odds of developing wheezing and 32% higher odds of any respiratory symptom, independent of cigarette smoking.
Read studyAmerican Journal of Preventive Medicine
National longitudinal data: vaping was linked to higher odds of later COPD, chronic bronchitis, emphysema or asthma, even after accounting for smoking.
Read studyPNAS
After 54 weeks of nicotine vapour, 9 of 40 mice (22.5%) developed lung adenocarcinomas. None of the 20 mice given nicotine-free vapour did.
Read studyBMJ
Review of human, animal and cell research: vaping causes measurable harm to airway cells and lung defences, and removing combustion alone does not make a product safe.
Read reviewNational Academies of Sciences, Engineering, and Medicine
The US National Academies found conclusive evidence that e-cigarettes emit potentially toxic substances, and substantial evidence that using them leads to nicotine dependence.
Read reportJAMA Cardiology
Habitual vapers showed heart-rate patterns of heightened sympathetic (stress) activity and more oxidative stress than non-users, both markers tied to cardiovascular risk.
Read studyNew England Journal of Medicine
CDC analysis of the 2019 to 2020 vaping lung-injury outbreak: more than 2,500 people hospitalised and dozens of deaths, many of them young adults.
Read studyNew England Journal of Medicine
Detailed report of previously healthy young people hospitalised with severe lung injury after vaping. Many needed intensive care.
Read studyThese studies cover the mechanisms and ingredients Harb is built around, and the ones it leaves out. They are not trials of Harb itself.
