It is usually known, that during long-haul flights some measurements must be taken to avoid veins clots. Eg.: stand up and walk once a while or take a antithrombotic shot before flight.
Yet I never heard of similar advice before long-haul bus rides, and they can take even longer (eg. bus from Buenos Aires to Lima takes 3 days).
Are flights more dangerous than bus rides, or are they equally risky?