Schools in North Sydney are imploring the state government to guarantee that ventilation stacks from road tunnels for the proposed Western Harbour Tunnel and Beaches Link not be built within a kilometre of their grounds.

Fearing for the health of students, five schools including Wenona and North Sydney Boys' High said placing non-filtered ventilation stacks in an area proposed in North Sydney "seems irresponsible at best, and potentially negligent at worse".

In a letter to state politicians on behalf of the schools, Wenona principal Briony Scott said it was dispiriting that the road tunnel project had "given no consideration" to increased car emissions in an area of North Sydney with a high number of schools.

"There are already significant pollution concerns from existing traffic routes," she wrote.