## 4 Discussion
After the flight, the RBC solution (#5-2) was transferred into the ATR, and the temperature continued to rise up to 7.0 \({}^{\circ}\)C because of the residual heat and recovered below 6 \({}^{\circ}\)C in 10 min until 11:29 in ATR (data not shown). The temperature inside the transported box B was high at >8 \({}^{\circ}\)C before the flight, and up to >9 \({}^{\circ}\)C until landing, and it seems that the temperature in the external environment had risen. This might be due to the exhaust tube of the UH or some gap between the Type III and RBC solution, and the temperature rise in the unmeasured area was >6 \({}^{\circ}\)C for a long time. Although the type III results were slightly poor, the results after filtration suggest that the temperature spike may not have substantially affected the RBC solution. In Japan, RBC solutions must be stored at 2-6 \({}^{\circ}\)C. The recent change from a 30 min to a 1 h deviation suggests that the increase in temperature in a short period is not a significant problem [21]. Moreover, we detected sustained vibrations in UH, although sudden vibrations are probably greater in vehicles. The vibration did not seem to affect the blood in this study compared to when transported by car or aircraft. However, whether any vibration can cause hemolysis remains unelucidated. Recently, [PERSON] et al. reported on vibrations in drones for insulin, which is easily degraded, in particular, the difference between the vibration inside the container and the vibration outside the container, which was significantly attenuated by the container [22]. In our study, we only measured the vibration logger attached to the outside of the container which only measures low frequencies; therefore, the extent of the vibration inside the container, especially high-frequency vibrations, which might have a strong impact on the blood, remains unknown. However, even if blood is more affected by the vibration of UH than of other vehicles, the effect is likely to be less than the degradation caused by temperature changes. In a study by [PERSON] et al., the effects of 10-30 g vibrations for 1-2 h on blood are considered to be a problem [23]. In our study, the sudden vibration of approximately 4 g, and the continuous vibration of about 2 g, showed no significant effect although there appeared to be problem with the logger's vibration frequency sensor. Since the frequency that the logger can detect is 0-60 Hz and the engine speed at cruise is 600 rpm (100 Hz), we believe that the actual acceleration is higher than the measured one. This study focused on the safety of transported blood for transfusion. Blood products are similar to drugs as they are not dangerous substances, while specimens can be dangerous substances [18]. Blood specimens that have not been tested for the hepatitis virus or HIV are potentially more dangerous than drugs and should not be treated the same as blood transfusion products; however, blood products are considered drugs approved by the Japanese Pharmacopoeia and are not hazardous materials that can be transported on regular passenger planes [24]. Even if they are hazardous materials, there is no problem in transporting them by ATR, which is allowed to transport them in the same way that they are normally transported on airplanes because the blood is first protected by a plastic pack, then in a plastic bag, plastic tray, and finally in an outer box that has gaps due to the structure of ATR 700. In box A, the blood pack is contained in a plastic case with a space and an outer box containing interference material, and blood for transfusion is not a dangerous substance; therefore, there should be no problem. Box A is also used for blood transport by passenger aircraft in the Amami region. Box B, which was created to transport specimens by drone, has a triple-layered structure consisting of a blood pack covered by a plastic bag, an interference space, an air-filled interference material, and an outer shield. Notably, LDH and AST, especially LDH, were used to assess hemolysis.