This video has just been published and is going around which shows HCHO levels are dangerously high coming straight from the Antminer A3. https://www.youtube.com/watch?v=k4SlUW1LWoU
For those who aren't familiar with what HCHO does cancer.gov states the short-term effects are "individuals may experience adverse effects such as watery eyes; burning sensations in the eyes, nose, and throat; coughing; wheezing; nausea; and skin irritation" along with The International Agency for Research on Cancer (IARC) classifies formaldehyde as a human carcinogen.