Low Emission Zones in Europe

We are leaving soon for a trip through Belgium, Netherlands, Germany, Denmark and Sweden and we wonder what experience members have of these low emission zones.  We understand that if we fail to display the correct sticker we can be fined 40Eu on the spot.  Has this happened to anybody and what is the best way of coping with it?  We have applied for a sticker on a Berlin website but it may not arrive in time for our departure and would only cover Germany in any event.  The websites are not clear enough in their information and advice.  I wish we had a Europe-wide system.