CC everyone in your office in, and your union rep if you have one! Send an email like the below, outlining your objections, and your requirements for actually doing the job.
"Hi Manager,
I wanted to follow up on what was discussed at the meeting this morning regarding the cleaning of the office.
I'd like to strongly object to the cleaning duties being assigned by rota. These are not in my job description or contract, and no consultation on the take up of extra duties has taken place.
I would also ask whether appropriate training will be provided, if these duties are required, as upon verbal enquiry, we've been told 'you're adults, just get on with it'.
If these duties are to be completed on a rota system, this should be by everyone in the office, without prejudice to rank, role or gender. Currently, X is not on the rota, and has verbally confirmed that 'he doesn't have time for that', as I'm sure you're aware, we are of equivalent grades, and therefore if his job role won't be adapted to include the cleaning, mine shouldn't be either.
I'd also like to register an objection to being expected to train others in an area which I have not been trained, as XXX made a comment of 'the women can show the men how to do it', which I am uncomfortable doing, having not been trained myself in this area.
I'd also ask whether there will be a renumeration in terms of money, or dropping of other duties to accommodate the time required to to fulfil these new duties? And if so, what money/ time is to be allowed for this?
I'd also like to see a full formal risk assessment for staff cleaning the office/kitchen/ toilets, which should include full COSHH reports for each cleaning product to be used. As I'm sure you'll be aware, a full risk assessment is required for any tasks not covered by existing risk assessments. As this is a new duties for staff within the office, I have not seen a risk assessment for this, and am not comfortable performing this duty unless I see a full risk assessment first.
Please note that I have copied the entire office into this email, as I do believe many others will have the same objections and queries. I have also copied in union rep, who will be assisting me in representing our staff's interests going forwards.
Please respond asap. I will be unable to take up any of these additional duties until I have had the above answered."
I've worked in places (not offices, more retail/hospitality), where staff do cleaning, and all the things like risk assessments, COSHH sheets, cleaning rotas etc are fully available, and managers are able to provide training in anything required if needed (even casual training - you'd be surprised how many people can't mop properly). There's also cleaning oversight in terms of having things checked off by a manager, and proper storage of cleaning chemicals. If your manager is serious about putting this in, they need to provide all the above, and address the inequality in the rota!