Hypoxia from long standing (chronic) lung disease and smoking are common causes of polycythemia. Therefore, smoking can be significant risk factor for polycythemia.
Chronic carbon monoxide (CO) exposure can also be risk factor for polycythemia. Hemoglobin has a higher affinity for CO than for oxygen; therefore, as it replaces oxygen in favor of CO, polycythemia may ensue to compensate for the low oxygen carried by hemoglobin.
Chronic carbon monoxide exposure is a risk factor for people working in underground tunnels or parking garages, cab drivers in highly polluted and congested cities, or workers in factories with exposure to engine exhaust.
People living at high altitudes may also be at risk of developing polycythemia due to low environmental oxygen levels.
People with genetic mutations and familial types of polycythemia and certain hemoglobin abnormalities also carry risk factors for this condition as mentioned in earlier sections.