①Measured every 6 months and reported
② Measured every 6 months but not reported
③ Measured every 6 months but unclear whether reported or not
④ Not measured every 6 months but are reported
⑤ Not measured every 6 months not reported
⑥ Not measured every 6 months and unclear whether reported or not
⑦ Unclear whether measured every 6 months or not
⑧ Not applicable (there are no hazardous substances)