Since an association was only found with green dust, it is more
likely to be related to agents, such as resin acids or
monoterpenes, which are present at elevated levels during
pine processing, particularly in areas in which fresh wood is
sawn [28]. These agents may either be allergenic themselves
following oxidation [29] or possibly act as adjuvants, increasing
the risk of becoming allergic to other agents. Microbial
agents present in the sapwood of fresh pine logs may also play
a role [30].