There are studies that compare the remaining toxicants to exposure limits for workplaces. I can find you several, there are some in the links I provided, including the air in a vape shop with heavy use.You can calculate the figures for formaldehyde etc, and you would need to take more than 8,000 puffs a day to reach the limit for exposure. In the 1 million puffs survey the highest recorded was just over 1200, and an average of 500 or so a day.