In seeking regulatory approval overseas for iQOS, an electronic smoking device, Philip Morris International Inc. is claiming the product is less likely to cause disease than traditional cigarettes. But the iQOS, which is gaining popularity in Japan, holds another, less obvious advantage over regular smokes: the ability to harvest personal data about users' smoking habits.

The tobacco giant is already building a database of iQOS customers who register with the company. And it has developed a software application that could take things a step further.

The initiative, if allowed by regulators, could extract information about a user's smoking routine from the device and use it for marketing purposes, said a former project manager at the company who tested the software in Japan. That data would include the number of puffs and average consumption per day, said Shiro Masaoka, who worked at Philip Morris in Japan from 2012 to 2016.