Injuries associated with poorly-functioning, propane-powered forklift trucks are reported extensively in occupational health literature.
In a well-functioning, propane-powered forklift truck, fuel combustion produces water vapour and carbon dioxide. But, when the fuel mix is incorrect, particulates and carbon monoxide (an odourless gas that is taken up preferentially by haemoglobin in the blood) can be produced instead. The risks associated with this can range from headaches, dizziness and nausea to acute carbon monoxide poisoning[1].
Incidents of carbon monoxide poisoning associated with LPG-powered forklifts in industrial settings were highlighted in a 1999 report by the United States Centers for Disease Control and Prevention[2]. The report set out a number of occasions where employees regularly suffered the first signs of carbon monoxide poisoning.
Up to half of those who suffer severe carbon monoxide poisoning are thought to experience long-term neurological or psychiatric symptoms. These symptoms can fall into three categories - changes in behaviour, movement (motor abnormalities), and memory or thinking (cognitive dysfunction).
When speaking to a forklift truck worker who experienced severe carbon monoxide exposure, he told me that he didn’t recognise the symptoms mentioned above, but he did report feeling “down”, experiencing higher levels of anxiety than previously and severe fatigue.
This is unsurprising given a case control study[3] of the neurological consequences of carbon monoxide poisoning found while there was no difference between groups when cognition was tested, patients who had experienced carbon monoxide poisoning did have a lower quality of life, were more depressed than those who had not been exposed to carbon monoxide and suffered more from post-traumatic stress disorder. They also showed significantly lower cognitive performance on processing speed, mental flexibility, inhibition, and working and verbal episodic memories. The prognosis of symptoms resulting from carbon monoxide poisoning are not well documented.
Due to the high frequency of injuries associated with using an LPG-fuelled forklift indoors, in the United States, it is considered good practice for employees to be trained to recognise the symptoms associated with carbon monoxide poisoning.
Unfortunately, the Health and Safety Executive in the UK seem less concerned with these dangers. They provide only the briefest of warnings in the rather unhelpfully titled COSHH (Control of Substances Hazardous to Health) SR14[4] and this devotes just one line to the subject: “Test LPG fuelled engines for carbon monoxide emissions regularly”.