Exactly how hazardous is it to break a fluorescent bulb and release the mercury inside it?

To my knowledge there is no non-toxic alternative to Mercury for fluorescent bulbs.I believe they should be sold in an air- tight, reasonably strong plastic container, which the dead bulb is put back into, and then put into a recycle bin. This would prevent it being broken,and they would then be separated at the recycling center and sent back to manufacturer, or recycled locally. They should not go into landfill. Mercury is very toxic and persistent.

Answer:

First off, the average CFT contains 4 mg Hg. Usually this is isolated from the environment and poses no problem and if recycled is no problem for its total life cycle. However if broken or trashed and broken can release the Hg vapour. By comparison the old 48" tube contains 10-25 mg Hg in vapour and liquid form.

The mercury is there because the vapour conducts electricity and in the process gives off ultraviolet (UV) light. The UV in turn excites the lining of the bulb to give off visible light

Lets talk about the "oops!" factor. What happens if you break one of the bulbs. The Hg is released into the immediate vicinity of your lungs and then ...

Some jurisdictions stop just short of having you call out the Hazmat team. However many of us remember playing with mercury as kids - lots of skin and respiratory exposure and we're apparently okay. Hg, by the way, attacks the central nervous system, and causes eye, skin, and respiratory tract irritation. Don't forget our favourite Hg exposure victim - the Mad Hatter from Alice in Wonderland.

Our friends at the US Occupational Safety and Health Administration (OSHA) have established permissible exposure limit (PEL) for mercury vapor at 0.1 milligram per cubic meter (mg/m3) of air as a ceiling limit. The National Institute for Occupational Safety and Health (NiOSH) has a recommended exposure limit (REL) for mercury vapor of 0.05 mg/m3 as a time-weighted average (TWA) for up to a 10-hour workday and a 40-hour workweek. exposure. The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned mercury vapor a threshold limit value (TLV) of 0.025 mg/m3 (25 ug/m3) as a TWA for a normal 8-hour workday and a 40-hour workweek.

On the bright side, the Hg does leave your body. It has a half life of about 1 month. So each month you have only half of what you stated with at the start of the month. The related problems are yours for much longer.

For serious occupational exposure consider the dentist. At the dentist's breathing zone, mercury vapour concentrations of ten times the current ACGIH occupational exposure limit of 25 μg/m3 have been recorded after 20 minutes of continuous aspirator operation. A build up of Hg amalgam contamination within the internal corrugated tubing of the aspirator was found to be the main source of mercury vapour emissions followed by particulate amalgam trapped within the vacuum motor. As the vacuum motor heated up with run time, mercury vapour emissions increased. It was found that the bacterial air exhaust filter (designed to clean the contaminated waste air entering the surgery) offered no protection to mercury vapour. In this case the filter trapped particulate amalgam which contributed to further mercury vapour contamination as high volume air was vented through it.

Now back to the dropped bulb. Assume the bulb releases all of its 4 mg into the air of your average room. Based on how quick the smell of burnt toast, cigarette smoke or intestinal gas permeates a room this rapid dilution seems reasonable. A room is about 2.5 m by 4 m by 3m (for ease of calculation) or about 30 m3 - immediate maximum concentration is therefore about 0.103 mg/m3, a bit above the maximum level of 0.1 mg/m3. Since the whole house or apartment gets the diluted air over time the 8 or 10 hour standard is probably reached - it would be a good idea to air the place out for the same duration as for burnt toast or Uncle Jack's gas.

Then sweep up the broken bits into a baggie and dispose with the trash.