The public were protected by a milk distribution ban, which was instigated at a radioactive iodine-131 activity concentration in milk of 3.7 kBq/litre – this ban, imposed for a few weeks, covered a coastal strip of land from 10 km north of Windscale to around 20 km to the south, a total area of  about 500 km2 and affecting about 600 farms. The highest I-131 activity concentrations in milk in farms close to Windscale were around 30 kBq/litre (which compares with the highest levels in the same area after Chernobyl of around 0.4 kBq/litre). The milk withheld from sale was poured away.