The 35% is a meaningless number without more details. It's not shocking at all if a 1km column of smoke blocks more than 35% of the light passing along it. So w

The 35% is a meaningless number without more details. It's not shocking at all if a 1km column of smoke blocks more than 35% of the light passing along it. So we need to know more about the test to decide if it's shocking or not - specifically the distance the light travels through the sample. Integration time is also important. Short bursts of dense smoke can be equally polluting as a continuous stream of light smoke.