• Smoking cessation

The popularity of electronic (e)-cigarettes, or ‘vapes’, has increased dramatically across the world in the last decade, with market shares now measured in billions of dollars. This has driven constant reinvention, creating new, ever more powerful devices and a wide variety of e-liquids. These e-liquids typically contain humectants such as propylene glycol and vegetable glycerine, which act as the delivery agents for nicotine and a vast array of flavouring compounds. In many ways, this mirrors the progression of the tobacco cigarette market, initially sold based on promises of health benefits and an ever-expanding variety of brands driven by provocative marketing.

E-cigarettes are accepted to be a significantly lesser harm than cigarette smoking and now recommended by public health agencies for smoking cessation, with clinical trials evidence finding e-cigarettes twice as NRT in helping smokers to quit.1 This is of importance to reduce the burden of smoking-related diseases such as cancer, cardiovascular disease and chronic obstructive pulmonary disease (COPD). Patients with COPD (characterised primarily by airflow obstruction) often present with a high pulmonary neutrophil burden and significant tissue remodelling (emphysema) from the resultant increased proteinase load. Much of the research to date has focused either on efficacy in smoking cessation or in defining relative harm versus cigarette smoking, by assessing impact on lung health by measuring early markers of COPD.

The field currently lacks long-term cohort studies comparing the effects of vaping and smoking, which makes quantifying harm or benefit difficult, however, there is a growing body of evidence examining the effect of e-cigarettes on immune health.2 Ex vivo3 4 and in vivo murine models5–7 have shown a significant negative impact on pulmonary immune response. These …