The regulations on trucks (and diesel service vehicles in general) needs to be much more stringent, especially those that pass through urban centers. That is an

The regulations on trucks (and diesel service vehicles in general) needs to be much more stringent, especially those that pass through urban centers. That is an industry that has pushed back at every turn and people just get misdirected to blaming Sally Suburban. The same thing happens regarding roads in general where we often imagine that industry and goods still appear at their destinations and the world rolls on if all of the roads were turned into parks. That's the general case, though. This school might be dealing with other particulate sources, as another comment mentioned a large number of industrial sources nearby (e.g. cement plants are a big source). In which case maybe the school just isn't in the best place. And it's worth noting that we now measure and pay attention to this but it was much worse in the past. Smelling the wonderful smell of a wood burning fire is usually an indication that you're in a dangerous particulate zone.