‘All they knew was that it was toxic, corrosive, and we had many casualties’

On 10 December 2024, a tanker overturned on the Humber Bridge in the north of England spilling its contents onto the carriageway and adjoining slip road. At that same moment, at a country park at the bridge’s northernmost end, unsuspecting members of the public gathered for a fun run.

The scene had all the makings of a disaster. Thankfully, it was a staged scenario with actors, carefully designed to train local emergency services in how to handle major incidents – in this case, a potentially deadly chemical leak.

These types of exercises are a routine part of emergency service response training, but when it comes to incidents involving chemicals and hazardous materials, chemists play an invaluable role in advising response teams on the safest ways to handle them.

Keeping people safe

‘The primary aim of the [Humber Bridge] exercise was to test our ability to decontaminate mass casualties,’ explains Mark Walsh, a station manager specialising in emergency preparedness for Humberside Fire and Rescue Service. The location, equipped with a large car park, was chosen to allow the services to set up the appropriate decontamination facilities – a sizeable structure containing showers and private areas to enable casualties to be undressed with dignity.

The scenario was aided by around 40 volunteers from nearby colleges and some willing senior citizens who took the role of the fun-runner casualties in the incident.

‘We focus very much on what the blue light response would be to mass casualties,’ explains Walsh. ‘But, equally as important is how we communicated and worked together to make sure we were all [focussed on] the same objective: to keep people safe [and] to prevent escalation of an incident.’

The Humber Bridge scenario aimed to simulate the response to a spill of phosphoric acid and hydrofluoric acid – both corrosive acids that can cause severe injuries, including burns and damage to the eyes, respiratory and gastrointestinal tracts. The choice of chemicals was designed to represent a worst-case scenario that would require a response from ambulance crews as well as the fire service.

Those leading the exercise withheld information about the hypothetical substances for as long as possible so information could be drip-fed to those involved, as it would be in a real-life situation.

‘All they knew was that it was potentially toxic, corrosive, and we had this number of casualties that were affected by it,’ adds Walsh.

Expert advice

To set up a realistic scenario, those organising the exercise needed advice on which chemicals to design the event around, the risks they pose and, ultimately, how best to deal with them. For this, they had scientific support from chemists at Bureau Veritas – an organisation that provides risk management, testing, inspection, and certification services at various locations around the UK.

‘We provide scientific support advice to different emergency services across the country,’ says Stephen Yao, an organic chemist and scientific advisor at Bureau Veritas.

If a fire service comes across a fire involving a hazardous chemical or stumbles across a drugs lab in a domestic property, Bureau Veritas would advise them on how to proceed, Yao explains.

‘We would advise them on what the chemical is, what the typical hazards are … sometimes it’s illicit laboratory setups [so we would advise on] how to dismantle them, and even safe disposal,’ he adds.

As well as providing a 24-hour support line for emergency services, Yao and his colleagues also assist with training exercises like the one at Humber Bridge.

‘Oftentimes we give them a sample list, and then estimate how the scenario will go based on that … [then] we will liaise with the managers of each service and have a discussion about what they want to achieve – we’ll just sit around and brainstorm any ideas that are potentially interesting.’

For December’s exercise, Bureau Veritas supplied Walsh’s team with a generic UN number for a corrosive, but undefined, chemical – as would typically be displayed during transport. It was then the responsibility of the responders to contact the transport company or manufacturer to find out the exact identity of the substance.

Yao explains that in a chemical spill scenario there are many different parties who will potentially be involved.

‘The first would be the fire service which has full authority over that incident, then there will perhaps be the company that owns the chemical, or the tanker or equipment that is storing the chemical that’s now leaking, [and] another player in there would perhaps be the Environment Agency,’ he says. ‘Everybody there will have their own best interest in mind … [and] sometimes the best way forward isn’t black and white.’

Generally, Yao and his team are called on to help with chemical leaks once or twice a month. These range from the inert but potentially hazardous leaks, such as liquid nitrogen tank failures, to incidents involving much more harmful gases such as chlorine, ammonia and refrigerants.

Proportionate response

Ed Sullivan is head of chemical and response training at Ricardo, an organisation providing technical expertise to various clients across the world and which operates the UK’s National Chemical Emergency Centre (NCEC). He notes that a chemical used in lot of NCEC training scenarios is anhydrous ammonia, which is widely used as a refrigerant gas.

‘It’s a very, very interesting product,’ says Sullivan. ‘We spend a lot of time educating people on what the risks are, then how do you deal with it when worst case scenario happens? What about the people? What about casualties? Is it a saveable life? Is it not a saveable life? Are we talking body recovery instead – there’s a risk–benefit analysis that incident commanders are trained to carry out.’

When it comes to casualties, Sullivan says the mantra is ‘remove, remove, remove’.

‘We remove the casualty from the risk area … We then remove their outer clothing, and then we rinse them, removing the rest of the product through a thorough rinsing process,’ he says. ‘For the majority of incidents, a version of that will work as effectively as anything possibly can.’

Proportionality is another key aspect of the training Sullivan delivers. This helps to guide the actions responders take by considering the quantity of hazardous material being dealt with – has a teaspoon of chemical spilled, or a 35,000 litre tanker?

‘Over the last decade there’s been an effort made to bring in this proportionate response to things so that we don’t need a massively resource intensive response for something that is actually quite manageable,’ he explains.

For Sullivan, one of the most important actions category one response teams can take to improve their response to a scenario involving a hazardous material is to build relationships with the people who have ownership over the risk – for example, the companies involved in manufacturing or transporting hazardous chemicals.

‘Build the relationship between industry and the emergency services. If you’ve never met them, get on the phone, and that is [to both] the fire service and industry,’ he says. ‘They need to get to know each other and work together more collaboratively.’

These connections can speed up the identification of a spilled chemical. But in situations where the chemical’s identity remains unclear, testing can sometimes be done on site. Sullivan explains that there are mobile laboratories strategically located around the UK that can be used to detect and identify different substances. He also notes that increasing numbers of fire services have the capacity to carry out wet chemistry field testing.

‘You can use pH paper, oxidizing paper, some basic field testing, energetic testing, and a whole host of other things to try and identify what it is you’re actually dealing with,’ he explains. ‘Would you get a chemical name from that? No, but it will tell you which UN classification it sits within, which is a good start.’

Like Bureau Veritas, the National Chemical Emergency Centre has a team of highly trained chemists who offer category one responders – mostly the fire service but sometimes the police – support 24 hours a day, 365 days a year.

‘These chemists will help the hazmat tactical advisor, who will put that call in to try and identify what it is,’ says Sullivan.

‘My opening gambit [during training sessions] is that we’re not here to teach you to be a chemist, we are here to enable you to understand [the] physical properties [of hazardous materials], and build your own black book of, “I don’t know the answer to this, who do I phone?”.’

Most traditional hazmat incidents are in the dangerous quadrant of being both low frequency and extremely high risk. In contrast, house fires and car crashes, are far more common and therefore often the main focus for fire service training. However, Sullivan explains that more training is needed, particularly as decarbonisation efforts mean that new chemical hazards are becoming more prevalent.

‘There are new risks posed to us from alternative fuels, for example,’ he says. ‘And, with lithium-ion batteries we’re dealing with fires you can’t put out. Industry needs to take more responsibility to enable the emergency services to understand what they may be having to respond to.’

The aim of these training scenarios is ultimately to keep the public safe and Walsh hopes that awareness of exercises taking place, like that at Humber Bridge, can offer reassurance. However, he highlights that it’s important to understand that it is not just the emergency services playing a role. ‘We train on these scenarios regularly, but we don’t do them in isolation,’ he says. ‘It’s all the support [of people] that are non-uniformed that people don’t notice – like Bureau Veritas and local resilience forums – it’s those people that allow us to do the more visible side of things.’