Hence, this research has shown that the compound BaP used as a
marker for the mixture of PAH in the standard recommended by
EPAQS represents a very similar proportion of the carcinogenic
potential of the PAH mixture present in indoor air to that in outdoor
air. Consequently, application of the EPAQS standard as a guideline for
the quality of indoor air is likely to afford a similar level of protection
to its application to the outdoor atmosphere. However, taking account
of the fact that most people spend at least 90% of their time indoors, it
is arguably equally important to limit PAH concentrations to below
the level of the EPAQS standard in indoor air as it is in outdoor air.