Thank you for sending the photos of your trees. It is hard to tell from a photo exactly what is causing the needle browning. Needle loss can be a sign of pests or disease, or abiotic environmental factors such as air pollution, herbicides, salt, over fertilization, drought, and winter injury. It can also be part of the natural process of die back, as trees shed lower branches that don't get enough sunlight.

Do you see any cankers or fungus on the tree trunk? Or indication of pests (galls, webbing, frass)? Has anything changed recently in your yard or neighborhood, such as a new neighbor spraying herbicides, or construction nearby?

I would recommend looking closely at your tree for any signs of pest or fungus, and then find a consulting arborist in your area to assess the health of the trees. A consulting arborist will give a risk assessment report without any interest of cutting down the trees. It is a special certificate issued through the American Society of Consulting Arborists. You should be able to call local arborists and ask if they have a consulting arborist on staff. 

You can also look at the PNW pest management handbook for ideas of what diseased Douglas-fir trees look like, and compare and contrast to your own trees: https://pnwhandbooks.org/plantdisease/host-and-disease-descriptions?title=Fir%2C+Douglas+%28Pseudotsuga+menziesii%29