Can't see the image properly on my phone but it doesn't look like dust blobs to me. These tend to be in one or two place not covering the entire screen. Has this just appeared or been slowly getting worse?
If you minimise the image down to the smallest possible size and press the Pattern button on the bottom left of the remote you should be able to make out the blobs as specs on the screen.
Unfortunately Epson pjs are partial to dust blobs in the same way Oliver Reed was partial to a drink
Emailed Epson and apparently I'm still in warranty, therefore they're sending an engineer around to try to fix and then if not, swap out the unit. Hopefully a good result.
As you have defocused the the image on the projector, I feel there are dust blubs. However there is also something else going on here. The uniformity is wrong and this is not a dust blob feature.
So, you have two issues here, one is that you have quite a few dust specs, the other is the uniformity is not right. This looks like the optical block issue or a filter issue with the light output from the projector degrading one of the other.
It should have a constant white-ish colour across the screen and not a pinky to white at one edge and a blue to white at the other edge. This could mean one of the two things that I mentioned above.
Dust blobs create an issues with uniformity, however this projector also has blue and redish/pink tint to the opposite edges to the image, which are tell tell signs that something else is going on here. It's doesn't mean the projector is dead either as with age this happens to many LCD projectors. Shining a bright light through something which can discolour can only have one outcome.
See how bad it is once its been cleaned. I still feel the uniformity will still show, but not in the same was as the first image as that is certainly dust.
According to Epson, it will be replaced if the engineer cannot repair the fault onsite (got an engineer coming tomorrow). They haven't said anything about cleaning it.
The convergence on this protector is bad too. There's a green line down each side of the screen.
Never had a humidifier in the room. It's on a high shelf with a small gap behind the projector allowing decent airflow. Regularly clean the filters, etc.
Epson guy been and gone and the projector has been swapped out for a reconditioned model.
Much more white I think and the dust appears to be gone. The bizarre thing is that when defocussing, I still can see all the same artifacts as I could before