Trimble Tech High School in Fort Worth dismissed early Wednesday after several teachers and students reported difficulty breathing.
Clint Bond, with the Fort Worth Independent School District, said the fire department checked the building but found nothing wrong with the air quality.
The district's own environmental team also checked the school and found nothing wrong as well, Bond said.
No hospitalizations or further injuries were reported by the district.
The district will allow the building to air out overnight and said Thursday's classes will take place as normal.
