Answer:
sudden change in temperature, which can make the blood vessels narrow.
very strenuous or excessive exercise, due to shortage of oxygen.
dehydration, due to low blood volume.
infections.
stress.
high altitudes, due to low oxygen concentrations in the air.
alcohol.
smoking.
Step-by-step explanation:
Any event that can lead to acidosis, such as infection or extreme dehydration, can cause sickling. More benign factors and environmental changes, such as fatigue, exposure to cold, and psychosocial stress, can elicit the sickling process.