How to communicate to my co-workers that they don't have to say “bless you” when I sneeze?
The best I know, so far, comes from Ask A Manager: “I know I sneeze a lot, just give me a ‘blanket bless you’ for the day.” With a big smile, as usual :)
In some countries in Europe, and as far as I know, sneezing is sometimes seen as "not so polite" (I was raised that way). Therefore, acknowledgement is also "not so polite". That's why many people, after sneezing, say excuse me, and no one answers, depending on the culture and education.
But it's also something that you can't control.
Some say something, some don't. Check the local rules there, it can be different from country to country. Same at the workplace.
The practice of blessing someone after a sneeze is probably as old as the first century. The origin of the practice is most likely rooted in superstition: the belief that a sneeze is the body trying to rid itself of evil spirits, the thought that the heart stops beating when a person sneezes, or the fear that a sneeze somehow opens the body to evil spirits. In these cases, saying, “God bless you,” was a kind of protection or good luck charm that shielded the sneezer from being invaded by spirits or affected by evil. (From Got Questions)
This way, you are polite, you don't say anything rude to co-workers, and may stop them from doing it again. They know you heard them, and that they don't have to say it all the time. No real way out though, if people were raised saying "whatever is nice after sneezing".
How can I communicate (actively or passively)?
The first time it happens, you'll have to say something. Not answering would lead to 2 things: rudeness and do-it-again attitude from both sides. You have to let them know. But I strongly recommend that you avoid the passive-aggressive approach, especially at the workplace. This would most probably lead to damaging the atmosphere within the cubicle.
Related: 1. myths and clarifications about sneezing 2. feel obligated to say bless you: can we stop? 3. saying bless you when a coworker sneezes 4. sneeze etiquette