Table 1

Studies included in the review

	Authors, year of publication	Funder, country	Study design	Heat-not-burn and reference products	Main aim
Studies on HnB mainstream emissions
1	Auer et al,21 2017	Independent, Switzerland	Laboratory comparison study using smoking machines	IQOS Cigarette	To compare levels of HPHC in mainstream IQOS emissions with those in mainstream cigarette smoke.
2	Farsalinos et al,222018	Independent, Greece	Laboratory comparison study using smoking machines	IQOS Cigarette E-cigarettes: (i) Ciga-like (ii) eGo-style, second generation (pen-style tank) (iii) Variable wattage (tank model)	To compare levels of nicotine in mainstream IQOS emissions from regular and menthol tobacco sticks with nicotine in different type of e-cigarettes aerosol and in mainstream cigarette smoke.
3	Bekki et al,23 2017	Independent, Japan	Laboratory comparison study using smoking machines	IQOS Cigarette	To compare levels of nicotine and HPHC in mainstream IQOS emissions from regular and menthol tobacco sticks with those in mainstream cigarette smoke.
4	Schaller et al,24 2016	PMI, Switzerland	Laboratory comparison study using smoking machines	THS 2.2/IQOS Cigarette	To compare levels of HPHC in mainstream IQOS emissions with those in mainstream cigarette smoke.
5	Schaller et al,25 2016	PMI, Switzerland	Laboratory comparison study using smoking machines	THS 2.2/IQOS Cigarette	To compare levels of HPHC in mainstream IQOS emissions from regular and menthol tobacco sticks with those in mainstream cigarette smoke.
6	Jaccard et al,26 2017	PMI, Switzerland	Laboratory comparison study using smoking machines	THS 2.2/IQOS Cigarette	To compare levels of HPHC in mainstream IQOS emissions with those in mainstream cigarette smoke.
7	Pratte et al,27 2017	PMI, Switzerland	Laboratory comparison study using smoking machines	THS 2.2/IQOS Cigarette	To compare numbers of solid particles in mainstream IQOS emissions with those in mainstream cigarette smoke.
8	Eaton et al,28 2018	BAT, UK	Laboratory comparison study using smoking machines	THP 1.0/glo Cigarette	To compare levels of HPHC in mainstream glo emissions with those in mainstream cigarette smoke.
9	Forster et al,29 2018	BAT, UK	Laboratory comparison study using smoking machines	THP 1.0/glo IQOS Cigarette	To compare levels of HPHC in mainstream glo emissions with those in mainstream IQOS emissions and cigarette smoke.
10	Poynton et al,30 2017	BAT, UK	Laboratory comparison study using smoking machines	iFuse Pen-style e-cigarette	To compare levels of HPHC in mainstream iFuse emissions with those in mainstream Vype ePen emissions and cigarette smoke.
Studies on HnB secondhand emissions
11	Protano et al,31 2016	Independent, Italy	Laboratory comparison study using smoking volunteers	THS 2.2/IQOS Cigarette Hand-rolled cigarette E-cigarette (pen-style tank)	To compare levels of secondhand emissions.
12	Protano et al,32 2017	Independent, Italy	Laboratory comparison study using smoking volunteers	THS 2.2/IQOS Cigarette Hand-rolled cigarette Cigar Pipe E-cigarette (pen-style)	To compare levels of secondhand emissions.
13	Ruprecht et al,33 2017	Independent, not reported	Laboratory comparison study using smoking volunteers	THS 2.2/IQOS Cigarette E-cigarette (cartridge)	To compare levels of secondhand emissions.
14	Mitova et al,34 2016	PMI, Switzerland	Laboratory comparison study using smoking volunteers	THS 2.2/IQOS Cigarette	To compare levels of secondhand emissions.
15	O’Connell et al,35 2015	IT, UK	Laboratory comparison study using smoking volunteers.	THS 2.2/IQOS Nicorette inhalator E-cigarette (cigalike)	To compare levels of sidestream emissions.
16	Forster et al,36 2018	BAT, UK	Laboratory comparison study using smoking machines	THP 1.0/glo Cigarette	To compare levels of secondhand emissions.
Studies on human use of HnB
17	Kamada et al,39 2016	Independent, Japan	Case report	IQOS	To report a case of acute eosinophilic pneumonia following use.
18	Lopez et al,40 2016	Independent, USA	Randomised crossover experimental trial	Pax LLTV Cigarette eGo e-cigarette (pen-style tank)	To compare nicotine delivery, expired air CO concentration and abstinence symptom suppression.
19	Brossard et al,43 2017	PMI, Japan	Randomised crossover experimental trial	THS 2.2/IQOS Cigarette Nicotine gum	To compare nicotine delivery and effects on urge to smoke.
20	Haziza et al,44 2016	PMI, Japan	RCT	THS 2.2/IQOS Cigarette	To compare exposure to HPHC during 5 days of use.
21	Haziza et al,45 2016	PMI, Poland	RCT	THS 2.2/IQOS Cigarette	To compare exposure to HPHC during 5 days of use.
22	Lüdicke et al,46 2017	PMI, Poland	RCT	THS 2.1 Cigarette	To compare exposure to HPHC during 5 days of use.
23	Lüdicke et al,47 2016	PMI, Poland	RCT	CHTP Cigarettes	To compare exposure to HPHC during 5 days of use.
24	Lüdicke et al,48 2018	PMI, Japan	RCT	THS 2.2/IQOS Cigarette	To compare exposure to HPHC during 5 days of use in confinement and further 85 days of use in an ambulatory setting.
25	Lüdicke et al,49 2017	PMI, Japan	RCT	THS 2.2/IQOS Cigarette	To compare effect on biologically and clinically relevant risk markers during 90 days of use.
26	Picavet et al,50 2016	PMI, UK	Randomised crossover experimental trial	THS 2.1 Cigarette	To compare nicotine delivery and effects on urge to smoke.
27	Gee et al,51 2017	BAT, Japan	Randomised crossover experimental trial	THP 1.0/glo IQOS Cigarette	To compare the puffing topography, mouth level exposure and average daily consumption.
28	Yuki et al,52 2017	JT, Japan	Randomised crossover experimental trial	PNTV/Ploom Tech Cigarette	To compare the pharmacokinetics of nicotine delivery.
Studies on HnB epidemiology
29	Tabuchi et al,41 2016	Independent, Japan	Epidemiological study	IQOS Ploom Tech Glo	To report awareness and use of HnB products in a nationally representative sample.
30	Tabuchi et al,5 2017	Independent, Japan	Epidemiological study	IQOS Ploom Tech Glo	To assess population interest, rate of use, predictors of use and perceived effects of secondhand HnB aerosol.
31	Brose et al,42 2017	Independent, UK	Epidemiological study	IQOS Ploom Tech	To assess awareness and use of HnB products in a nationally representative sample.

BAT, British American Tobacco; CHTP, carbon-heated tobacco product; HPHC, harmful and potentially harmful compounds; IT, Imperial Tobacco; JTI, Japan Tobacco International; LLTV, loose-leave tobacco vaporiser; PMI, Philip Morris International; PNTV, Prototype novel tobacco vapour product; RCT, randomised controlled trial; THP, tobacco heating product; THS, tobacco heating system.