The hydrogen iodide figure was given in grams rather than micrograms, putting it out by a factor of one million. The hydrogen fluoride concentration was given as 0.02 micrograms per cubic metre, but should have been 0.016 milligrams per cubic metre.
There was a discrepancy within the report on metals and metalloids. Its main body gave a figure of 0.02µg/m3 for nickel, but its summary and the letter gave a figure ten times higher.
DEFRA said the errors were due to type-setting and proof-reading failures.