A stand with the first (1st) seating board not more than 500 millimeters above grade of floor may be considered to have two (2) exits when the bottom of the stand is open at both ends. Every stand or section of a stand within a building shall have at least two means of egress when the stand accommodates more than fifty (50) persons. Every open air stand having seats without backrests shall have at least two (2) means of egress when the stand accommodates more than three hundred (300) persons.