Teachers are raising concerns over whether schools can remain open if Covid-19 numbers continue to rise.
It comes as a new report shows outbreaks in Irish schools have usually been small in scale.
The summer holidays are drawing to a close - and this week children will start returning to school
On Saturday the country saw daily covid-19 case numbers hit a 7-month high.
Taoiseach Micheal Martin has warned a peak may not happen until the end of September.
ASTI President Eamon Dennehy says this is concerning.
The HSE says data shows around 4% of children tested positive in the last school year.
The Department of Education has said schools will be give Co2 monitors to ensure quality airflow.
But the ASTI says many schools are still waiting for theirs - and that only half of classrooms will actually have them.