The permissible standard for Calcium Oxide is 5 milligrams of CaO per cubic meter of air averaged over an eight-hour work shift. Some countries have recommended 2 milligrams per cubic meter. CaO has been linked to many health hazards like irritation of the eyes, nose, throat and skin. Severe burns may result from contact with this chemical. It may also cause bronchitis and pneumonia. Long term exposure is said to cause skin ulceration and perforation of the nasal septum.