Sewer vent pipe cover/grill?

[atyoung]

My roof sewer vent pipe grill/cover has blown off. The pipe itself looks fiune. How vital is this grill? I assume it's to stop birds/leaves etc getting into the pipe. Replacing it is very difficult because of difficulty of access to that part of roof.

[plumbbob]

Anything that enters the soil pipe may cause an obstruction and henceforth difficulty may be experienced in finding and removing the blockage.

In reality this may be a minimal risk, but never the less, it is there, so ultimately, it is entirely your decision.