Spirometry standardisation

I am writing a protocol to try to standardise the health surveillance we do for Occupational asthma and occupational lung disease. Should spirometry be done standing up or sitting down please?

Occupational Asthma, Health Professional, 7/15/2011, 7/18/2011,

Spirometry should ideally be performed sitting down as some people can become light headed when performing a full FVC. It shouldn't make any difference to lung function values if they are performed sitting down compared to standing up as long as the person is sitting upright without crossing their legs.

7/18/2011