The objective of this study was to assess the validity of two questions about the perception of intensity of exposure to secondhand smoke (SHS) at home using as a reference environmental markers (airborne nicotine and benzene) and biomarkers of exposure (cotinine in saliva and urine). This was a cross-sectional study in a convenience sample of 49 non-smoking volunteers. We found a high correlation between self-reported SHS exposure and airborne nicotine (rsp=0.806, p<0.05), salivary cotinine (rsp=0.752, p<0.05), and urinary cotinine (rsp=0.626, p<0.05). We did not find differences between the score question and the conventional ones (p >0.05). In conclusion, the significant correlation of the two questions proposed with environmental markers and personal markers indicates their potential validity to assess exposure to SHS at home.

This work was supported by the Instituto de Salud Carlos III, Subdirección General de Evaluación, Government of Spain (PI081436, PI081339 and RTICC RD12/0036/0053), the Ministry of Universities and Research, Government of Catalonia (grant 2009SGR192 and 2014SGR689), the Directorate of Public Health, Ministry of Health (GFH 20051) from the Government of Catalonia, ISCIII-Subdirección General de Evaluación and by FEDER funds/European Regional Development Fund (ERDF)−a way to build Europe−. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 681040.