The literature provides conflicting data for phthalates with regard to some of the analytical endpoints. Therefore, to facilitate the choice of endpoints for the principal study, as well as to validate some study procedures, a 'Method optimization sub-study' will be performed prior to the start of the principal study. A maximum of 25 healthy subjects will be recruited for this sub-study, who will sign a modified consent that reflects their limited participation. These subjects will not be exposed to DBP or CA, but will only be recruited for collection of blood, nasal lavage, and nasal brushing, or a subset of these samples. They will only attend one visit to the Vancouver General Hospital, dedicating 1 - 3 hours of their time when participating in the sub-study. Moreover, prior starting the principal study (above), up to four healthy subjects may be recruited for a 'Pilot study' to optimize the logistics of the exposures and the experimental procedures of the principal study. These subjects will be subjected to CA exposure only and have all procedures and samples collected as described for the actual study with the exception of the bronchoscopy.