Gasunie is one of the biggest gas infrastructure companies in Europe. Within the company, we give safety the highest priority; it forms the basis of our license to operate. We abide by the strictest safety, health and environmental standards, both for our own employees, external contractors and the surroundings. Gasunie’s safety policy is thus characterised by a proactive approach which is designed to prevent accidents, incidents and hazardous situations. Besmette filterkaars

General rules Familiarise yourself with the situation at the installation or construction site where you are going to work as soon as possible Make sure you know who and what is where Take the precautionary measures that are appropriate to the work you are going to carry out Set aside enough time for safety: consider what could go wrong and whether you have done everything you can to prevent hazardous situations Remain alert at all times when you are working. If in any doubt, always ask or suspend activities where necessary.

Odorants (aroma compounds) Natural gas is naturally odourless. To ensure that it can be detected by smell, an odorant is added to it in order to warn consumers of gas leaks. The odorant which Gasunie adds is called tetrahydrothiophene (THT). The concentration of THT in the gas is 18 mg/m³. THT is a colourless liquid which smells of rotting eggs. The low detection threshold of this substance is especially vital. Properties of THT Colourless liquid Moderately volatile Highly flammable No statutory threshold Smells of rotting eggs Chemical formula C4H8S

Risks associated with THT Personnel Highly irritating to skin and respiratory system Nausea and headache on inhaling Flammable Noxious Environment Leaks can cause THT to spread through the air or ground water Even very small amounts will be damaging to the environment and will cause serious noxious odours THT can remain in the groundwater for many years, causing problems Exposure of personnel to THT Odorised gas: - Gasunie operating norm set by health and safety agency: 37 mg/m³ (10 ppm). This applies to an exposure level of 8h/day - For short-term exposure, a maximum norm of up to 20 ppm for 15 minutes applies

Pure THT: - When filling the tank, replacing containers, during maintenance, dealing with faults and incidents (leaks) - Outside: depending on the wind direction, minimal exposure - Inside buildings: minimal exposure due to opportunity to escape - Long-term exposure to THT does not occur at Gasunie - During dismantling work

Contact met THT ExposureAcute effects EyesRedness and soreness, tears, swelling, blurred vision InhalationHeadache, dizziness, nausea, vomiting, loss of coordination, blurred vision, sleepiness, confusion or disorientation, palpitations Exposure to increased concentrations (extreme exposure) can affect the central nervous system Skin Irritation. Damage to internal organs due to absorption by the skin is unlikely Swallowing Stomach cramp, stomach ache, nausea, dizziness Can enter the lungs directly, causing damage or death

First aid on contact ExposureFirst aid EyesRinse with water for at least 15 minutes Consult ophthalmologist InhalationFresh air Rest Consult doctor Skin Remove contaminated clothing Rinse skin with plenty of water or have a shower Consult doctor Swallowing Rinse mouth out Give casualty carbon to eat (carbomix) Call in emergency medical aid without delay

What personal protection equipment to use? The personal protection equipment for THT are primarily designed to prevent contact with the skin. Exposure to high atmospheric concentrations is prevented by the very low odorant threshold of 3.6 microgrammes per m. During maintenance work Face visor/full-face mask, acid protection goggles Liquid-resistant gloves Acid protection apron Liquid-resistant disposable overalls (PE) Gloves Safety boots (PU) Helmet Eye protectors

In the event of high concentrations (e.g. when clearing up spilled product or during dismantling work) Full-face visor with ABEKHgP3 filter Alternative: oxygen mask Preparation of the work Make sure you are aware of the risks involved in the work Discuss the risks with the supervisor/client Make the necessary preparations Use the correct personal protection measures What to do in the event of a leak Wear the correct PPE Extra ventilation Contain and suck up spilled or leaked product Clean up residue of product with absorbent solution Neutralise odour with AIR-O-GONE if possible Notify CCP in the event of leaks that could cause problems in the environment