Formaldehyde in buildings
Irritation caused by formaldehyde in new or refurbished buildings is quite a common problem. The main sources of the formaldehyde are MDF, plywood, chipboard and fibreboard. The best prevention method is to ensure that correctly specified materials are used. Once emitted, formaldehyde vapour can be absorbed by soft furnishings, plasterboard etc., which act as a sink or reservoir, and re-emit it over long periods.
The main symptoms of exposure are irritation of the eyes, nose and throat, together with concentration-dependent discomfort and lachrymation. It also causes additional concern because it has been classified as a Group 1 human carcinogen by IARC.
The lowest concentration that has been associated with nose and throat irritation after short-term exposure is 80 parts per billion (ppb), although some individuals can sense the presence of formaldehyde at lower concentrations. The UK has a Workplace Exposure Limit (WEL) for formaldehyde of 2,000 ppb, both as a 15 minute and an 8 hour limit. Not only is this out of line with most other countries, which have Occupational Exposure Limits of around 300 ppb, but it is inappropriate as a guideline for members of the public and office workers. The most appropriate guideline in such cases is in the World Health Organisation (WHO) Air quality guidelines for Europe . To prevent significant sensory irritation in the general population, the concentration of formaldehyde should not exceed 80 ppb (0.1mg per cubic metre) averaged over any 30 minute period. This is also considered to represent an exposure level at which there is a negligible risk of upper respiratory tract cancer in humans.
Here are a couple of recent case studies:
Case Study 1 – Simple Partitions in a Room
Partitions made of MDF and plywood were being erected within a room. The installers, and others who entered the room reported eye irritation and an acrid smell. At first they suspected the concrete into which they had been drilling, because they first noticed the irritation about 30 minutes after drilling into a particularly hard area, but this turned out to be a red herring. On a site visit three days later, testing with a colorimetric tube over a ten minute period found a formaldehyde concentration of 1,000 ppb.
The partitions were removed, and the supplier replaced the materials free of charge. The problem was solved.
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Case Study 2 – A More Extensive Refurbishment
A building was converted into individual offices with new walls and floors made of plywood, and the walls faced with plasterboard. About six months after occupation, some staff and members of the public started reporting symptoms of streaming eyes and a metallic taste. An air survey found concentrations of formaldehyde of 400 – 1,100 ppb, and the offices were closed. A few months later, Industrial Health Control became involved. Advice was given to remove soft furnishings, and to increase the temperature and ventilation in order to try and speed up the offgassing. Logging formaldehyde meters were used to monitor the airborne concentrations. The formaldehyde levels fluctuated widely, often for no apparent reason, and could be very different in different parts of the building.
Here is one example of the monitoring results over a few days.
Formaldehyde, temperature, humidity monitoring
One immediate point is that monitoring over just a few hours would give a very incomplete picture. The facilities staff were instructed to open the windows for ventilation each day, as they had to be kept closed at night for security reasons. You can see on the graph how the concentration falls to nearly zero when this is done, only to rise again after they are closed, and rises even more at the weekend when the windows clearly were not opened.
Over two months the formalehyde concentration fell from 400-1,000 ppb to 200-750 ppb, and after another two months to 80-200 ppb. However, this fall then levelled off. In the end, it was decided to replace the new walls and floors completely. It has been known to take up to five years to eliminate formaldehyde from a badly contaminated building.
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In order to prevent this sort of formaldehyde problem from arising in the first place, all relevant building materials shouldconform with the Class 1 formaldehyde specification in British Standard BS EN 300:2006[i], when measured in accordance with BS EN 120:1992[ii].
[i] BS EN 300:2006. Oriented Strand Boards — Definitions, classification and specifications, British Standards Institution.
[ii] BS EN 120:1992. Wood based panels. Determination of formaldehyde content. Extraction method called the perforator method, British Standards Institution.
The NIOSH RELs are 16 ppb (8-hour TWA) and 100 ppb 15 min/ceiling. Which one(s) did you find were exceeded.
As I mentioned above, it’s a common problem which can be avoided by correctly secifying the materials used in the building. I gave the appropriate British Standards because that’s where I’m based. I beleive that the American standards for low formaldehyde emission products are ANSI A208.2-1994 for MDF, ANSI/HPVA HP-1-1994 for plywood, and ANSI A208.1-1993 for particle board. Are these the current standards? Do you know if the MDF used in the film construction shops that you surveyed conforme with these standards?
I recently completed my summer Co-op with a non-profit organisation that takes care of health and safety in the film industry. I sampled for formaldehyde exposure in film construction shops that use significant amounts of MDF and measured concentrations over NIOSH REL.Workers complained of URT irritation,wood dust and formaldehyde may be showing a synergistic effect.