Hazard Watch: Polycyclic Aromatic Hydrocarbons (PAHs) in the workplace

Chlorine is widely used as a disinfectant and in chemical, plastics, pulp and paper manufacturing, it is a highly reactive, toxic gas that can cause a variety of health issues. Because liquid chlorine readily vaporises and forms dense, ground hugging clouds, accidental releases present an acute risk; EH40 cites a short term reference limit of 0.5 ppm. Employers must use fit for purpose PPE, emergency procedures, engineering controls and regular monitoring to keep employees safe, services we can provide alongside technical guidance and UKAS accredited laboratory analysis.

Ammonia (NH3) is widely used as a fertiliser, refrigerant and in chemical manufacturing is a colourless, pungent gas that can irritate the nose and throat at relatively low concentrations and cause severe lung damage at high levels. With an HSE workplace exposure limit of 50 ppm workplaces must implement ventilation, PPE and regular monitoring using appropriate sampling media. Our laboratories offer UKAS‑accredited ammonia analysis and sampling support to help employers verify controls and protect their workforce.

Mercaptans, also called thiols, are pungent-smelling organic compounds used as odorants and in products from pesticides to animal feed. While their strong scent helps detect leaks, mercaptans can be highly flammable and harmful to health: low-level exposure causes eye, skin and respiratory irritation, headaches and dizziness, and high exposures may lead to severe respiratory effects. UK HSE exposure limits exist for common mercaptans (for example, methyl mercaptan 1.0 mg/m³), and employers must assess and control these risks under COSHH to keep workers safe and avoid enforcement action.