“As such, we continue to regard Nielsen’s data with some skepticism due to the frequency of Nielsen’s data revisions and the magnitude by which Nielsen often underestimates volumes in many key categories.”

The volume decline is partially caused by a recent 11-cent per pack price increase and by electronic cigarettes being increasingly adopted as a viable nicotine alternative.

Part of the decline also can be attributed to wholesalers and retailers stocking up on inventory ahead of the price increase in February.

Those groups typically pass along list price increases to consumers.

“There is on-going debate about how accurate these numbers are, given the rapid (and possibly increasing) rate of decline in cigarette sales,” said David Sweanor, an adjunct law professor at the University of Ottawa and the author of several e-cigarette and health studies.

“There is a reluctance to accept that Nielsen data showing sales falling by around 10% could be correct, even when the rapid rise in the sale of vaping and other non-combustible alternatives lends credence to the idea that cigarette sales are, in the historic sense of the term, being decimated.”