The occurrence of headache was independently associated with the use of a filtering mask , OR 2 . 14 ( IC95 % 1 . 07 - 4 . 32 ) , being a nurse OR 2 . 09 ( IC95 % 1 . 18 - 3 . 72 ) or another health worker OR 6 . 94 ( IC95 % 3 . 01 - 16 . 04 ) or having a history of asthma OR