Edit. After Black September's assassination of Israeli athletes at the Munich Olympics in 1972, Prime Minister Golda Meir okays a black-box operation to hunt down and kill all involved.
Yellow pollen is produced by evergreen trees, primarily pine trees, including spruce, true cedar trees, fir trees, larch and hemlock. Although yellow pollen looks like it could cause an allergic reaction, in reality it does not trigger allergy symptoms at all. It can stain the skin and clothing, however.
For the pollen to get from the male flower to the female flower, it has to travel, usually via wind. This is what makes these heavy pollinators an allergy culprit. Dioecious tree species bear male and female flowers on separate plants. Dioecious trees include ash, boxelder, cedar, cottonwood, juniper, mulberry and yew.