EricP coughed up some electrons that declared:

On Mon, 3 Nov 2008 11:30:49 -0800 (PST), benpost
wrote:

its now too cold to open the top smaller windows to the latch position
to help airflow/avoid condensation, but luckily ive got trickle vents
which are open now. i just wondered how best to clean them and ensure
they are not blocked?

A small bottle-brush may help

I've sucked mine clear with a hoover before and that did the trick.

Cheers

Tim