There are some people for whom the slightest odour of fresh paint can be overwhelming.   Paints and their residue odours they can cause nausea, headache and minor irritation of the eyes and throats in some people.  

Newly decorated rooms should be well ventilated both whilst the work is been carried out and for a prolonged period afterwards.

Consider using low odour waterborne paints instead of traditional solvent based products on your woodwork, metalwork, and also on varnished timber surfaces.   Low odour paints are not completely odour free, so remember to always ventilate the work area.

Odours from emulsion paints used on walls and ceilings can also accumulate in a confined space and therefore cause irritation to some people.

Wallpapers, especially vinyl's can release chemical odours for many hours after their application; I therefore recommend leaving bedrooms unoccupied for at least 24 hours after wallpapering so as to allow for all odours and excess humidity to disperse.

A simple but effective process for disguising lingering paint odours is to employ a large onion and two breakfast bowls.    I have used this technique many times and find it most effective.

Firstly cut the onion through its middle dividing its top and bottom.

Then place each onion segment in the bowls, exposed centre up and then add cold water to just below he cut edge.

Place the bowls in the newly decorated room and close the door as best you can.  Leave them in place overnight and then discard.

You might notice a slight oniony odour, but it will overcome the paint odour in a cheap natural organic way and may help those who might be suffering from the effects of paint odours.