"begin quote" This is a copy-paste of a comment I made on another post, but I felt it needed a little more attention since it has some useful information.
This is the original post and this is the study.
According to OSHA, the permissible exposure limit for formaldehyde is 0.75 parts per million on a time weighted average of 8 hours per day. That converts to 0.92mg/m3 or 4.416 mg per day.
Assuming you take 1000 'puffs' from your vaporizer a day, using their numbers, you get somewhere between 0.2mg and 0.04mg of formaldehyde. This is for lower voltage, for 4.8 volts the value is 1.8mg.
Warning: Math
I converted PPM to mg/M3 using this website's formula. I then multiplied the average breath (0.5L or 0.0005m3 ) by the average respiration rate (8 hours X 60 minutes X 20 breaths a minute) to get 4.8m3 in an 8 hour period. That multiplied by 0.92mg/m3 gets the total of 4.416mg. To be conservative I assumed this amount applies to a 24 hour period, rather than 8 hours.
Consequently, this source claims natural exposure to the chemical is usually around 0.5?g/m3 , or roughly 2.4?g per 8 hour day.
Edit: Using similar math I get a max consumption of 0.34mg of Acetaldehyde where the STEL/ceiling value allows for 216mg/day. (25 PPM STEL/ceiling value.) Studies have shown indoor values to be as high as 18?g/m3, or 86.4?g in 8 hours.
Edit 2: Acetone is 1000ppm PEL per 8 hour TWA, I'm not even going to bother.
TL;DR: Formaldehyde may be an issue, but is well within occupational/environmental limits imposed by government agencies. The other two chemicals are present at levels near natural environmental levels, if you work in an office and live in a house/apartment.
Update: Now that I know the volume of vapor inhaled, here is some more information. Going back to assuming 1000 puffs per day, the total volume of inhaled vapors a day would be 0.0047m3 (That's 70mL converted to 0.00007m3 then divided by 15 and multiplied by 1000), providing the user with 1.8mg of formaldehyde. Let's double that just for fun (I'm working with the worst case scenario according to this study, remember) and say it's 3.6mg per day. That's still slightly below (18% less than) the OSHA standard of 4.416mg per day. (Where the hell are these people working?)
Using the same data of 0.0047m3 inhaled, acetaldehyde provides a delicious 0.282mg. If we multiply that by 100 (that's 100,000 puffs) you get 28.2mg, or a little under 1/7th the daily STEL/ceiling value for that chemical.
Going with acetone, we get a daily allowance of 11,370mg or so. Going with the 1000 puff standard you get a grand total of 0.506mg. Multiply that by 10,000 (10,000,000 puffs, you monster!) any you're at 5,060mg, still less than half of the daily exposure limit.
TL;DR THE SECOND: Original TL;DR still holds up. I'm still somewhat concerned about formaldehyde at high (4.8V) voltage, but the other two chemicals are most likely not an issue."end quote"
This is the original post and this is the study.
According to OSHA, the permissible exposure limit for formaldehyde is 0.75 parts per million on a time weighted average of 8 hours per day. That converts to 0.92mg/m3 or 4.416 mg per day.
Assuming you take 1000 'puffs' from your vaporizer a day, using their numbers, you get somewhere between 0.2mg and 0.04mg of formaldehyde. This is for lower voltage, for 4.8 volts the value is 1.8mg.
Warning: Math
I converted PPM to mg/M3 using this website's formula. I then multiplied the average breath (0.5L or 0.0005m3 ) by the average respiration rate (8 hours X 60 minutes X 20 breaths a minute) to get 4.8m3 in an 8 hour period. That multiplied by 0.92mg/m3 gets the total of 4.416mg. To be conservative I assumed this amount applies to a 24 hour period, rather than 8 hours.
Consequently, this source claims natural exposure to the chemical is usually around 0.5?g/m3 , or roughly 2.4?g per 8 hour day.
Edit: Using similar math I get a max consumption of 0.34mg of Acetaldehyde where the STEL/ceiling value allows for 216mg/day. (25 PPM STEL/ceiling value.) Studies have shown indoor values to be as high as 18?g/m3, or 86.4?g in 8 hours.
Edit 2: Acetone is 1000ppm PEL per 8 hour TWA, I'm not even going to bother.
TL;DR: Formaldehyde may be an issue, but is well within occupational/environmental limits imposed by government agencies. The other two chemicals are present at levels near natural environmental levels, if you work in an office and live in a house/apartment.
Update: Now that I know the volume of vapor inhaled, here is some more information. Going back to assuming 1000 puffs per day, the total volume of inhaled vapors a day would be 0.0047m3 (That's 70mL converted to 0.00007m3 then divided by 15 and multiplied by 1000), providing the user with 1.8mg of formaldehyde. Let's double that just for fun (I'm working with the worst case scenario according to this study, remember) and say it's 3.6mg per day. That's still slightly below (18% less than) the OSHA standard of 4.416mg per day. (Where the hell are these people working?)
Using the same data of 0.0047m3 inhaled, acetaldehyde provides a delicious 0.282mg. If we multiply that by 100 (that's 100,000 puffs) you get 28.2mg, or a little under 1/7th the daily STEL/ceiling value for that chemical.
Going with acetone, we get a daily allowance of 11,370mg or so. Going with the 1000 puff standard you get a grand total of 0.506mg. Multiply that by 10,000 (10,000,000 puffs, you monster!) any you're at 5,060mg, still less than half of the daily exposure limit.
TL;DR THE SECOND: Original TL;DR still holds up. I'm still somewhat concerned about formaldehyde at high (4.8V) voltage, but the other two chemicals are most likely not an issue."end quote"
we are still way below the danger areas 
