They'd be less exposed to nicotine in your second hand vape than if they ate any of the following, which also contain nicotine
Vegetable Nicotine in ng/g g per 1µg nicotine
Cauliflower 16.8 59.5
Eggplant (Aubergine) 100.0 10
Potatoes 7.1 140
Green tomatoes 42.8 23.4
Ripe tomatoes 4.3 233.0
Pureed tomatoes 52.0 19.2
1µg of nicotine is the equivalent of sitting in a vaguely smoke filled room for three hours. However, vaping does not emit smoke. A cigarette contains about 7mg of nicotine, of which 1mg is absorbed. In other words, 100g of eggplant contains 0.01mg of nicotine, and 10kg of eggplant is equivalent to one cigarette. However, absorbtion rates from ingestion are low and nicotine is quickly metabolised, so the effect isn't nearly the same.
Edit: Sorry, but I couldn't get the columns to line up right. I pasted it from the internet. The first column of numbers is the amount of nicotine in ng/g, and the second column of numbers is the amount g per 1 µg nicotine.