Questions about perceived severity	Cronbach’s Alpha
The need for blood in Greece has increased due to the increase in traffic accidents.	0,748
The needs for blood in Greece are greater during the summer months.	0,743
Greece imports blood from abroad to meet the needs of patients with Mediterranean anemia.	0,746
Greece is one of the countries that cannot meet the needs for blood only through voluntary blood donation.	0,746
Greece has one of the lowest rates of voluntary blood donors in the world, compared to developed countries.	0,742
The need for blood in Greece has increased due to the increase in surgeries and transplants.	0,749
Questions about perceived susceptibility
If I or someone of mine needed blood transfusions were hardly enough people to donate blood.	0,745
A possible lack of blood supplies would endanger my life or the life of mine.	0,752
Young people are not going to need blood.	0,747
Only people with certain conditions, such as Mediterranean anemia, need blood.	0,745
I will only give blood when one of my own people needs it.	0,752
Questions about perceived benefits
When I give blood, I feel that I offer to society as a whole.	0,753
When I give blood, I feel that I am doing well in my health.	0,752
I give blood so that there is a deposit in case I or someone of mine needs it.	0,744
I donate blood to be tested for communicable diseases (e.g., hepatitis, HIV)	0,741
I give blood to get leave from my job.	0,748
When I donate blood voluntarily, I have the right to have free medical examinations - check-ups.	0,736
Questions about perceived barriers
I am afraid that frequent blood donation may negatively affect my health in the future.	0,744
I'm afraid of needles and/or blood.	0,746
After giving blood, I will be more prone to diseases and viruses.	0,745
I'm afraid that during the blood donation, I may catch a contagious disease.	0,739
I am afraid that during the blood donation, I may feel dizzy/faint.	0,752
I do not have time to go and donate blood.	0,751
The opening hours of blood donation services are limited and do not make it easier for me.	0,751
I am afraid that from the medical examination before or after the blood donation, I may find out that I have some disease or health problem.	0,748
Questions about cues to action
The reminder through SMS or email would encourage me to donate blood.	0,744
It would encourage me to donate blood by watching related commercials on T.V.	0,748
There must be financial incentives for someone to donate blood.	0,750
There must be better information about the blood donation process to the general public.	0,755
I would be encouraged to donate blood by having mobile blood donation crews near my home/work area.	0,751
Questions about self-efficacy
I believe I can become a regular blood donor.	0,753
I believe that I will be able to donate blood within the next six months.	0,755
Questions about Kessler Psychological Distress Scale (Κ6+)
During the past 30 days, about how often did you feel nervous	0,686
During the past 30 days, about how often did you feel hopeless	0,679
During the past 30 days, about how often did you feel restless or fidgety	0,603
During the past 30 days, about how often did you feel so depressed that nothing could cheer you up	0,691
During the past 30 days, about how often did you feel that everything was an effort	0,692
During the past 30 days, about how often did you feel worthless	0,684
Taking them altogether, did these feelings occur more often in the past 30 days than is usual for you, about the same as usual, or less often than usual?	0,682
During the past 30 days, how many days out of 30 were you totally unable to work or carry out your normal activities because of these feelings?	0,681
Not counting the days, you reported in response to Q3, how many days in the past 30 were you able to do only half or less of what you would normally have been able to do because of these feelings?	0,677
During the past 30 days, how many times did you see a doctor or other health professional about these feelings?	0,661
During the past 30 days, how often have physical health problems been the main cause of these feelings?	0,694