Cement smell from mortar or bricks in wall

There has been a strong 'wet cement' smell coming from a wall on the boundary with our neighbour which was built (by the neighbour) some years ago under a party wall agreement, as part of an extension. It's very noticeable in hot weather, when it heats up.

The mortar is a grey colour, suggesting too much cement in the mix. The extension has had damp issues, which may be contributing to this ongoing smell problem although it might also be off-gassing.

Is there a clear waterproof and breathable sealant that I could apply to it on my side (to the mortar or the bricks or both) that would be non-toxic and would lock the fumes in? Recommendations for something cheap, but effective?

The neighbour isn't friendly and is unlikely to be willing to do anything to fix this problem, as it's only me that it bothers.

Storm dry masonry protection may work?

Evaporating moisture will bring any odour contamination with it, so will still smell.
Further, the molecules of any "fumes", will be smaller than that of any moisture, so will be given off from the wall if a breathable coating is applied.

Storm dry and suchlike is not a sealant like paint or varnish. It works by capillarity to stop moisture movement, but pores are left open to allow air movement and evaporation.

If you can smell damp, you have a damp problem and need to deal with that, not mask it.

Smells caused by a neighbour, directly or by poor design, may be actionable as a Statutory Nuisance. As would damp be. That's a legal route for uncooperative neighbours.

Is this smell in your house or just in your garden?

Are you sure it's cement? I like the smell of fresh cement, but it usually goes away in a day.

Is it a bit mushroomy, like a woodland walk? In which case it's probably mould, which may or may not be related to the building work.