The letter comes as MPs prepare to vote next week on Government proposals for a part-ban across England - a move which would worsen health inequalities say the authors, a Director of Public Health and colleagues working in South London.
A part-ban would mean that smoking would be banned in pubs and bars serving hot food, while those not serving food would be exempt, and customers could continue smoking.
In a snapshot survey of nearly 500 pubs selected randomly, the authors found there was a strong, direct correlation between wealthy areas and pubs selling food - which would be smoke-free under the proposals. In the richest areas as many as 88% of pubs and bars would come under the ban, protecting staff and customers against the effects of smoking and second-hand smoke, say the authors.
But in the poorest areas, far less pubs - less than half (46%) - sell food, so far fewer pubs would be subject to a ban on smoking. This would mean that some of the most deprived people in the country would be left most exposed to the risks of passive smoking.
This is direct evidence of the likely affects of the Government's proposals, say the authors. There can now be no doubt that the health gap between the most affluent and the worst off in society would be exacerbated by a partial ban, they conclude.