We use an air-sampling device called a Burkard spore trap to capture airborne pollen on to tape attached to a drum that rotates past the air inlet opening. We then take the tape off and mount it onto a microscope slide, which we stain with a dye and count using a microscope. We count all types of pollen on the slide as well as just the grass pollen (which has a distinctive shape). Our daily pollen count is a report of grass/all kinds of pollen (as grains per cubic metre of air) caught in the trap in the previous 24 hours. Our pollen forecast is based on this count and on the weather forecast for the next 7 days.