The British Department for the Environment, Farming, and Rural Affairs (DEFRA) has announced that farmers do not need to give prior notice before using pesticides on their crops.
This means that if you live in the UK you cannot be sure whether your area is contaminated by pesticides.
Regardless of whether this decision is right or wrong, it is vital that if you live in a rural area, you consider the risk of pesticide contamination. Your shoes may pick up traces of the stuff. Make sure you remove them at the door and ask visitors to remove their shoes.