Not being an expert in dust sampling and measurement I would take a dose of practicality here.
I am anticipating that arborists and forest workers are generally operating chainsaws on fresh live timber that has a relatively high moisture and sap content. Much like our regulator advice for wet cutting practices while working with products containing silica, these workers get a natures equivalent for dust suppression.
The simplest way is to undertake some measurement and prove or disprove that an issue exists.