What is Phosphine Gas PH3?

Phosphine gas is a highly toxic, respirable substance commonly generated during fumigation processes on farms, where aluminium phosphide tablets react with moisture in the air. Once inhaled, phosphine reacts with moisture in the lungs, producing acid and posing severe health risks. It is a colourless, flammable gas with no odour in its purest form. However, when contaminated, it may emit a garlic or rotting fish smell. Do not rely on smell to detect phosphine, as it can lead to dangerous concentrations in enclosed or poorly ventilated spaces. Being heavier than air, phosphine gas can accumulate quickly and is known to self-ignite, creating explosion risks.

Phosphine is naturally present in the atmosphere in trace amounts, produced through the decomposition of organic matter. It is widely used as a grain fumigant, rodenticide, and in microchip manufacturing. The permissible exposure limit (PEL) is 0.4 mg/m³. Exposure to phosphine, a potent redox toxin, induces oxidative stress, leading to cellular and mitochondrial damage. Symptoms of exposure include dizziness, headaches, and respiratory issues, and severe cases may result in death. Proper risk assessments and workplace safety measures are crucial for safe handling of phosphine.

Industrial and Agricultural Uses of Phosphine Gas

Phosphine gas is heavily used in various industries, including grain storage, pest control, and semiconductor manufacturing. It is also a byproduct of certain industrial chemical processes like welding and metal alloy production. Phosphine is extremely hazardous, and inhalation can lead to severe health complications, including respiratory distress, organ damage, and death.

 

Health Risks of Phosphine Gas Exposure

When inhaled, phosphine gas disrupts how the body absorbs and uses oxygen. Short-term exposure can cause:

• Headaches
• Respiratory problems (coughing, chest tightness, difficulty breathing)
• Dizziness, chills, confusion, and vision issues
• Fatigue, weakness
• Gastrointestinal symptoms like nausea, vomiting, and diarrhea

High exposure to phosphine gas can result in:

• Severe kidney, liver, and heart damage
• Pulmonary edema (fluid in the lungs)
• Convulsions
• Death

Chronic exposure to low levels of phosphine gas can cause long-term health problems, such as:

• Anemia
• Bronchitis
• Gastrointestinal disorders
• Speech and motor disturbances
• Weight loss
• Bone necrosis and spontaneous fractures
•  

Workplace Exposure Limits for Phosphine Gas

The recommended workplace exposure standard (WES) for phosphine gas is:

1. 0.3ppm (0.42 mg/m³) over an 8-hour time-weighted average (TWA)
2. 1ppm (1.4 mg/m³) for a short-term exposure limit (STEL) over 15 minutes

These standards are designed to minimize risks in environments where phosphine is present.

How to Manage Risks in the Workplace

Managing the risks associated with phosphine gas involves strict adherence to safety protocols. Workers and managers must collaborate to ensure safe use of phosphides and compliance with workplace safety regulations. Below are four key steps to manage phosphine hazards effectively:

1. Identify the Risk: Determine where and how phosphine gas is used or generated. Key risk factors include explosion hazards, health risks, and death.
2. Assess the Risk: Use questions such as:
   • Where are phosphides used or generated?
   • Are exposure levels being measured and tracked?
   • Who is exposed or nearby?
   • Are proper ventilation and safety measures in place?
3. Control the Risk: Implement safety measures such as:
   • Eliminating hazardous chemicals where possible
   • Using mechanical tools for handling phosphine tablets
   • Restricting access to hazardous areas
   • Using real-time dust monitors with alarms for gas detection
   • Ensuring proper ventilation and adherence to standing/re-entry times
   • Refraining from using smell to detect phosphine

Workers should wear personal protective equipment (PPE) such as full-face respirators when dealing with phosphine gas, especially in areas where the airborne concentration exceeds 0.3ppm. All filters and respirators should be suitable for short-term exposure and discarded immediately if phosphine odour is detected.

4. Review Risk Controls: Regularly review and update safety measures. Conduct routine checks to ensure all safety protocols are being followed and reevaluate when any changes or incidents occur.

By following these steps, businesses can ensure a safe environment and reduce the health risks associated with phosphine gas exposure.

The 04 Series PH3 personal single gas detector from Riken Keiki is a perfect solution. This single gas monitor is designed to operate for many years. These models have 2 preset alarms that are user adjustable. Each version is also equipped with visual, audible, and vibration alarms as standard. 

Sensors have a life expectancy of over 3 years and backed by a 3 Year Warranty. 

Each 04 Series monitor is impact, dust, and water resistant with an IP-67 rating. 04 Series instruments are safe for use in hazardous locations, classified as intrinsically safe IECEx/ATEX. 

Being Australia’s gas detection specialists, Control Equipment has a solution to most situations.