One of the most difficult tasks in all studies on passive smoking
has been to quantify the exposure to ETS. We have used
self-reported exposure in this study for quantifying the exposure.
The validity of self-reported exposure to ETS has been
tested in a large multi-country multi-centred collaborative trial
including Chandigarh, India, in which urinary cotinine levels
were found to correlate with the history of exposure to ETS.
The study demonstrated that non-smoking women could provide
appropriate estimates of their exposure which correlated
well with their biochemically measured exposure levels. A recently
published study has stated that self-reporting could be
underestimating the low levels of exposure.