Some orchardist or vineyard has been burning for several weeks now, and with a south westerly wind the results are clear (no irony intended).
I understand the ‘right to farm’ plays into allowing burning, but in the Lower Mainland the owner or contractor is required, by law, to use forced air. The burn is almost smokeless because the material is not smouldering.
Forced air burning is easily achieved with a large commercial fan powered by a gasoline engine.
Let’s get out of the dark ages; this sort of air quality is dangerous for someone with chronic obstructive pulmonary disease and people who are heavy smokers.

Pat Hampson, Oliver