Figure 6.

Influence of the smoke extract of the nicotine-free cigarette tar, free of the gas-phase components, on HRV in four non-smoking volunteers. PG0 refers to 25 puffs of the electronic cigarette with propylene glycol (control), and PGE pertains to 25 puffs of the electronic cigarette with the smoke extract, while NFC denotes 10 puffs of a Nirdosh nicotine-free cigarette. Designations of statistically significant differences (p < 0.05): a—relative to the baseline in the experiment with smoking (t = 0 h), b—in the experiment with smoking relative to the electronic cigarette with propylene glycol (PG0), c—in the experiment with smoking relative to the electronic cigarette with the cigarette-smoke tar extract (PGE), d—in the experiment with the electronic cigarette with the cigarette-smoke tar extract relative to the baseline (t = 0 h), e—in the experiment with the electronic cigarette with the tar extract (PGE) relative to the electronic cigarette with propylene glycol (PG0).