is it safe to paint stairs with emulsion paint?

It is possible to emulsion stairs but you would have to varnish them with an anti slip varnish. The varnish will also protect the emulsion from wearing off the stairs as emulsion is not hard wearing at all and is really only meant for walls and ceilings. I think Sadolin do an anti slip varnish it will have tiny gritty particles that will hopefully stop you slipping!!

I would skip painting stairs with emulsion and varnish and go straight for a floor paint. Farrow & Ball and Little Green do some lovely ones!

Varnish Over emulsion will dry yellow brown colour Your stairs I’d say are made of wood same as the rest of the wood in your home Whatever product you apply in time will wear off floor paints made for concrete not wood you need to wood Prime undercoat two coats of satin wood you could sprinkle some fine sand or salt over the final coat on to the treads to act as nonslip

I would advise against painting stairs with emulsion as its not very hard wearing and far better suited to walls/ceilings. I would also advise against painting floors or stairs with any gloss or varnish as they are slippery. Assuming your stairs are wooden, I would recommend using a wood priming undercoat and a maybe a Farrow & Ball floor paint. I've painted a few floors/stairs in Farrow & Ball and both the colours and finishes are amazing!