As thousands of Philadelphia parents weigh whether to send their children back to school buildings, a WHYY/Chalkbeat analysis of school has found that of elementary classrooms with completed reports lack even the minimum industry-recommended ventilation standards to safely hold 15 or more people.And one-fifth of elementary schools have no classrooms that can accommodate that many people while meeting the air circulation standards.Under the , about 32,000 students in kindergarten through second grade would have the option of returning to school two days a week, with half the group attending...…As thousands of Philadelphia parents weigh whether to send their children back to school buildings, a WHYY/Chalkbeat analysis of school has found that of elementary classrooms with completed reports lack even the minimum industry-recommended ventilation standards to safely hold 15 or more people.And one-fifth of elementary schools have no classrooms that can accommodate that many people while meeting the air circulation standards.Under the , about 32,000 students in kindergarten through second grade would have the option of returning to school two days a week, with half the group attending...WW…