It is a common occurrence for smokers to be given extra breaks during their working time in order to indulge in smoking a cigarette, however, it is not surprising that non-smokers are unhappy about it.
To foster a harmonious working environment, you should treat all employees equally to avoid giving them something to complain about. Creating two tiers of workforce can be divisive and lead to grievances being submitted from employees who feel particularly upset about the issue.
They may complain that they are picking up the slack of the staff who are allowed this extra break, having to answer their phone calls and deal with queries that come through. Your leniency towards staff who have a nicotine addiction has now landed you with a problem.
However, what you are effectively doing is reducing the working hours for those employees who smoke whilst others remain on the full working hours. Basically, you are allowing a paid break to some of your staff who for no particular reason deserve it, while leaving others out.
To call a halt to further complaints, you may need to consider stopping the smokers from having the break. There is no statutory entitlement to it, after all, but you may have created a situation where smokers feel they are now entitled to the break because it has been part of their day for so long. To soften the blow, you may have to consider offering another kind of incentive to staff.
Alternatively, you may ask that those who take time during the day for a smoking break make the time up later in the day. Or to fully even out the entitlement, allow all staff a five-minute break whether they smoke or not. It is commonly thought that stepping away from your workstation for a short time can provide the space needed to come up with a solution to problem that’s been bugging you all day.