Mystery of the Afternoon Headache in the Chemical Stores

The Plot

One cold wintry morning whilst visiting the factory floor, John the Storeman called to me from his fork lift truck to say that he had a persistent headache.

Walking towards him, my eyes picked out the black and blue drums of chemicals stored around and pallets of powders being lifted into place by the fork lift trucks. Idly I noticed the childlike skull and crossbones painted on the door that some comedian had painted in glaring white paint. This I knew was how the rest of the factory viewed the chemical storage area. A nuclear ‘no go’ area. Some even held their breath when visiting. But I was sure it was safe…..

The store-room was impressive with black and blue metal drums stacked neatly, it was tidy and clean. John stacked the chemical drums safely and complied with regulations. Stores personnel knew storing chemicals incorrectly could lead to spillage, reactions with other chemicals, fires or deadly fumes. A huge responsibility for John. I knew all the workers in the factory, meeting them on induction for health checking before starting work and for annual health surveillance too. Mainly they were young mischievous men who could tolerate the heat and heavy manual handling that the job involved. Two things influenced the culture in the factory. Work was scarce locally and the workforce took risks. So avoiding contact with authority (me!) was the norm. John (or anyone) asking about their personal health was something of a surprise.

John told me that he had started getting a persistent headache in the afternoon that lasted for the rest of the shift. The teasing from his work mates had caused him to think he was being slowly poisoned by the very air of the stores.  The skull and crossbones had done their work.


I asked John to see me later in the week for tests and started a background investigation of the chemical and other changes that may have affected the environment. The Store Room Manager and Production Manager both reassured me that nothing had changed, there were no new chemicals being used or delivered and no other workers had reported headaches or health problems. There were no issues with leaks or ventilation of the area. I asked for the batch of hazard data sheets of the substances stored and the risk assessments (see Control of Substances Hazardous to Health Regulations COSHH), and sat with a cup of coffee to look for the side effect of a headache in the tiny small print information on each sheet. I couldn’t find anything suspicious. I also talked to others in the vicinity of the storeroom before I saw John again.


Two days later John duly arrived in my office in the afternoon. Yes he still had the headache in the afternoon. I checked his blood pressure and did a few other tests. I asked about his past medical history and if he had any recent health issues. No! I asked if he had any new hobbies and if there were any home issues that could account for the headache. All proved negative with no stress at home or work to talk about. And then I had a thought [Tweet “Why only have a headache in the afternoon?”]

The Culprit

‘Do you have lunch here at the factory John?’ I asked ‘Yes – in my car. I like to listen to music and eat my sandwiches in peace.’

He pointed out of the office window at the battered blue mini parked behind my right shoulder. I loved the 60’s I thought….

Then came inspiration.

‘Do you run the engine to keep warm?’I asked

‘Yes, it’s freezing at the moment.’

‘Is the exhaust OK?’

‘Funny you should say that – it needs a new exhaust but I can’t afford one at the moment.’

And there it was.

I believed John was getting carbon monoxide into his car from the leaky exhaust and this was probably causing the headaches. I advised him to get his exhaust fixed as soon as possible and to have his lunch elsewhere, whilst we continued with the factory investigation. The next step, if we couldn’t find the cause of the headaches – was to call in the hygienists to measure chemical levels of fumes and to check on our control measures, an expensive but necessary option.

Watch video from the British Hygiene Society on what this entails:

Two days later John reported that his headaches had stopped. He was eating in the staff restaurant and had his exhaust replaced as well.

The Science Behind the Headache

Carbon Monoxide (CO)

The lethal consequences of CO in engine exhaust is tragically illustrated by the hundreds of persons who die each year from carbon monoxide poisoning caused by a running vehicles inside a closed garage. Others die or become ill in homes with attached garages, while stranded in their car, or while driving or riding in a vehicle with a defective exhaust system.

Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide (CO). Carbon monoxide is a toxic gas, but, being colourless, odourless, tasteless, and initially non-irritating, is difficult for people to detect. It is often produced in domestic or industrial settings by older motor vehicles and other gasoline-powered tools, heaters, and cooking equipment.

Symptoms of mild acute poisoning include light-headedness, confusion, headache, dizziness; larger exposures can lead to death.

Watch this 90 second video on how this happens.

Other Reading:

NHS Choices on what to do if you think you have carbon monoxide poisoning and how to detect and prevent leaks Remember too that deaths can occur in the home – always use a carbon monoxide monitor.

This is an extract from Jane Combs new book on workplace case studies that will be available later this year.  To find out more about occupational health and safety work and other interesting workplace facts sign up for the Working Well Solutions monthly newsletter here – have you ever thought you were being affected by work?  What happened, share your experience here.

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