- Exposure can occur when isocyanates are curing or when cured isocyanates are heated.
- An individual’s response to isocyanate exposure can be immediate or may be DELAYED FOR SEVERAL YEARS.
- Skin exposure can also cause respiratory sensitisation.
- The odour threshold for isocyanates, i.e. the level at which an individual can smell an isocyanate, is typically higher than the allowed exposure limits.
- The Air Corps did eventually provide a “supplied air” respirator to spray paint & welding personnel. Unfortunately they sourced the “supplied air” from an old machine compressor located in ERF where the air had previously tested as 3.5 times over the allowed limit for Dichloromethane i.e. allowed limit was 50ppm and sourced air was from a location measured at 175ppm…out of the frying pan and into the fire.
Air Corps Hexamethylene Diisocyanate Usage
Hexamethylene Diisocyanates were a chemical component of polyurethane paint hardener used by the Spray Paint Shop (Dope Shop) at Baldonnel. For most of the existence of this shop personnel were NOT supplied with ANY PPE. The walls between the Spray Paint Shop and Engineering Wing Hangar & Workshops were not sealed and so Hexamethylene Diisocyanate and other chemicals entered these workplaces whilst spraying was in progress exposing all personnel.
Furthermore if a component could not be removed from an aircraft for spray painting it was spray painted in-situ in Engineering Wing Hangar whilst unprotected line & tech personnel worked in adjoining offices & workshops or on other aircraft in the hangar.
Visiting personnel to Engineering Wing hangar such as BFTS personnel doing an IRAN, Heli personnel doing an overhaul & even Military Police on a walkabout were also exposed.
A “waterfall” system with an extractor fan was also present. Personnel spray painted aircraft components toward the waterfall which captured most of the over-spray droplets. Fumes from this waterfall were then extracted by a fan, up a duct and released at approximately 3m height where the prevailing winds then carried the extracted fumes in the doors & windows of :
- 5th Maintenance Engineers
- Air Corps Apprentice School
- Avionics Squadron
- BFW Stores
- Engine Repair Flight
- Old Tech Stores
- Training Wing HQ Prefab
- Parachute Shop
5-20% of people are prone to isocyanate sensitisation. and isocyanate cross sensitisation is a recognised phenomenon. Sensitisation is irreversible and unfortunately once sensitised it is next to impossible to avoid isocyanate allergy triggers in the modern environment as they are used to make all Polyurethane products.
It is also likely that health effects are suffered beyond the respiratory system & skin for example the gastric & nervous systems and it is also probable that sensitisation to isocyanates will lead to allergies to other unrelated chemicals leading to a cascade of triggering chemicals allergies & intolerance for over exposed individuals.