What is the toxicity level of SiF4 as a medium?

This can be discussed with those specializing in chemical engineering processes, and the user’s operating environment should be taken into account; if it is a dry environment, I believe the hazard level is moderate. If it is humid, hydrogen fluoride, a highly hazardous decomposition product, must be taken into account, as well as corrosion.

According to GB5044 \"Classification of the Hazard Levels of Occupational Exposure to Toxic Substances\", are there any relevant regulations?

Silicon fluoride 1. Physical and chemical properties: National standard code 23020; CAS number 7783-61-1. Chinese name: Silicon tetrafluoride; English name: Silicon tetrafluoride； Silicon fluoride, also known as fluorosilicic acid, has the molecular formula SiF4. It is a colorless, irritating gas that is hygroscopic; it produces dense fumes in humid air. Its molecular weight is 104.06. The boiling point is -65°C (at 24.1 kPa), while the melting point is -90.2°C (at 175.6 kPa). It is soluble in ethanol, ether, nitric acid, and hydrofluoric acid. Its density is 4.67 (at °C), with respect to water having a density of 1 ； Relative density (air=1): 3.6. Stability: Stable. Hazard symbols: 6 (toxic gas), 20 (corrosive). Main uses: Used in the production of fluorosilicic acid and lead fluoride; also used as a hardening agent in cement and artificial marble, as well as in the synthesis of silicone compounds. 2. Environmental impact: I. Health hazards. Route of exposure: Inhalation. Health hazards: This product causes severe damage to the eyes, skin, mucous membranes, and respiratory tract. Local corrosion is severe. Severe poisoning can lead to pneumonia and pulmonary edema. II. Toxicological data and environmental behavior: Toxicity: Highly toxic. Acute toxicity: LC50 1275 mg/m3 (inhalation, rats). Hazardous properties: Produces white, corrosive and irritating hydrogen fluoride fumes in humid air. It reacts violently with water to produce silicic acid and hydrogen fluoride. Combustion (decomposition) product: hydrogen fluoride. 3. On-site emergency monitoring method: Rapid test strip method ； Ion-selective electrode method 4. Laboratory monitoring methods: Ion-selective electrode method (GB7484-87, Water quality); Filter membrane fluoride ion selective electrode method (GB/T15434-95, Air) 5. Environmental standards: China (TJ36-79) – Maximum allowable concentration of harmful substances in workshop air: 1 mg/m3; China (TJ36-79) – Maximum allowable concentration of harmful substances in residential area air (fluorides): 0.02 mg/m3 (one-time value) ； 0.007 mg/m3 (average daily value). China (GB5048-92): Water quality standards for agricultural irrigation – Fluoride content: 2.0–3.0 mg/L (for irrigation in wetland and dryland farming, as well as for vegetable cultivation). China (GB11607-89): Water quality standards for fisheries – Fluoride content: 1 mg/L. China (GB5749-85): Sanitary standards for drinking water – Fluoride content: 1.0 mg/L. China (GB/T14848-93): Quality standards for groundwater (in mg/L); Class I: 1.0 ； Class II 1.0 ； Class III 1.0 ； Class IV 2.0 ； Class V, level 2.0 and above (fluorides): Chinese standard (GHZB1-1999) for surface water environmental quality (mg/L); Class I, level 1.0 and below ； Class II 1.0 ； Class III 1.0 ； Class IV 1.5 ； Class V 1.5 (Fluorides): China (GB8978-1996) Comprehensive Wastewater Discharge Standards (mg/L); Grade 1: 10 ； Level 2: 10–20 ； Grade 3: 20–30 (fluoride). China (GB5058.3-1996): Standard value for identifying the leaching toxicity of solid waste – 50 mg/L (fluoride). 6. Emergency response measures: I. Emergency response to leaks: Evacuate people from the area affected by the leak to an area upwind immediately, and establish a 450-meter exclusion zone to strictly control access. It is recommended that emergency responders wear self-contained positive-pressure breathing apparatus and protective clothing. Enter the site from the upwind side. Seal the source of leakage as much as possible. Ensure proper ventilation to accelerate diffusion. Sprayed water or foam is used to cool and dilute vapors, protecting personnel on site. Construct dikes or dig pits to contain the large amount of wastewater generated. Leaking containers must be properly handled, repaired, and inspected before being used again. II. Protective Measures: Respiratory protection: When the concentration in the air exceeds the permissible level, wear a self-priming filter-type gas mask (full-face mask). It is recommended to wear an air respirator during emergency rescue or evacuation. Eye protection: Protection is provided under respiratory protection. Physical protection: Wear a sealed gas-proof suit. Hand protection: Wear rubber gloves. Others: Smoking is strictly prohibited at the work site. Maintain good hygiene* habits. III. First aid measures: Skin contact: Remove contaminated clothing and rinse with flowing water. Seek medical attention. Eye contact: Immediately lift the eyelids and rinse thoroughly with plenty of flowing water or saline for at least 15 minutes. Seek medical attention. Inhalation: Quickly move to a place with fresh air. Keep the airways clear. If there is difficulty breathing, administer oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention. Fire extinguishing method: Firefighters must wear full-body fire and gas-resistant suits. Cut off the gas supply. **Cool the container; if possible, move it away from the fire to an open area. Extinguishing agents: fogged water, dry powder, sand.