Sulfur Dioxide (SO 2 )

1. Sulfur Dioxide (SO2)

2. Sulfur Dioxide - Overview • Physical properties • Colorless, non-flammable gas • Heavier than air • Strong, suffocating odor • Rotting eggs • Liquid under pressure • Readily soluble in water

3. Sulfur Dioxide - Overview • Over 13 million tons released each year from electric power plants • Primary environmental source: burning of fossil fuels • Major component of acid rain • Occurs naturally from the decay of vegetation

4. Sulfur Dioxide - Overview • Industrial use • Useful to terrorists seeking to spread fear and disruption

5. Sulfur Dioxide - Toxicity • Major route of toxicity is inhalation • Strong eye and skin irritant • Asthmatics more susceptible • Children more vulnerable • Greater lung surface area to body weight ratio • Increased minute ventilation per kg • Short stature

6. Sulfur Dioxide - Toxicity • Acute exposures • 5 ppm: nose and throat dryness • Airway restriction • 6-8 ppm: decrease in tidal volume • 10 ppm: sneezing, cough, expectoration, and eye symptoms • 20 ppm: severe bronchospasm • 50 ppm: upper respiratory symptoms

7. Sulfur Dioxide - Toxicity • 100 ppm: immediate health risk • 1000 ppm: death from severe respiratory depression • EPA • Long-term: 0.03 ppm, 1-year average concentrations • Short-term, 24-hour concentrations • Not to exceed 0.14 ppm more than once a year

8. Sulfur Dioxide - Toxicity • OSHA • 2 ppm over an 8-hour workday, 40-hour work week • 5 ppm for short-term exposure • NIOSH IDLH: 100 ppm

9. Protective Equipment • Positive-pressure, SCBA is advised • Chemical-protective clothing for exposure to the liquefied gas • Safety glasses, face shield, and rubber gloves provide adequate eye and skin protection

10. Detection • Distinct odor • Olfactory fatigue does not occur rapidly • Variety of monitors and gas sensors available commercially

11. Decontamination • Remove individuals from contaminated area • Remove and double-bag contaminated clothing and personal belongings

12. Decontamination • Eye exposure • Flush immediately with water • Irrigate continuously with normal saline • Proparacaine hydrochloride to assist eye irrigation

13. Decontamination • For skin exposure • Flush with water • Wash well with soap and water • Cover burns with sterile dressings • Avoid hypothermia in children and elderly

14. Signs and Symptoms • Adverse effects • Increased by formation of sulfates or higher sulfur oxides • Interactions with water and particulates • Clinical diagnosis • Intensely irritating to eyes and respiratory tract

15. Signs and Symptoms • Acute effects • Upper respiratory tract irritation • Rhinorrhea • Choking • Expectoration • Nosebleeds • Difficulty in swallowing • Oropharyngeal erythema • Coughing

16. Signs and Symptoms • Within 5 - 15 minutes • Temporary reflex bronchoconstriction • Increased airway resistance • Pulmonary infection from destruction of the ciliated epithelium • Asphyxiation from severe glottal and bronchiolar constriction

17. Signs and Symptoms • Eyes • Lacrimation, conjunctival injection, and blepharitis • Higher exposures: iritis

18. Signs and Symptoms • Severe eye injury • Liquid form of SO2 • Corneal epithelium turns gray and irregular remaining attached to stroma • Lids become edematous and conjunctiva appears white and opaque • Blindness may result

19. Signs and Symptoms • Dermal exposure • Irritation, urticarea, and burns • Major risk: liquid sulfur dioxide exposure

20. Signs and Symptoms • Metabolic acidosis • Blood alkali reserves reduction • Ammonia elimination in urine • Protein and carbohydrate metabolism disorders, along with possible • Effects the hemopoietic system and methemoglobin production

21. Signs and Symptoms • Chronic exposure • Permanent pulmonary impairment • Repeated bronchoconstriction episodes

22. Treatment • Basic first aid for victims • No antidote • Care is supportive • Monitor the cardiac rhythm • Treat arrhythmias • Precautionary intravenous line • Hypovolemia or shock • Use normal saline consider vasopressors

23. Treatment • Acidotic patient • Anticipate seizures • Treat with diazepam • Treat skin irritation and burns topically

24. Treatment • Establish patent airway • Intubate for upper airway obstruction • Maintain open airway with suctioning as necessary • Consider assisted ventilation

25. Treatment • Correct hypoxia with oxygen • Non-rebreather mask • Monitor the patient’s oxygenation status • Arterial blood gases or pulse oximetry • Watch for signs of pulmonary edema • IPPB, PEEP, or intubation

26. Treatment • For ingestions • Rinse mouth, administer water for dilution • DO NOT use emetics • Administer activated charcoal as a slurry • Consider a cathartic

27. Long-Term Medical Sequelae • Acute high-dose exposures • Severe obstructive and restrictive defects • High dose exposures (80 to 100 ppm) • Nasopharyngitis, dyspnea on exertion, and chronic fatigue • Lower exposures (2 to 36 ppm) • Respiratory disease symptoms

28. Long-Term Medical Sequelae • No studies linking to cancer • EPA classified as Group D • Reproductive and teratogenetic effects not known

29. Environmental Sequelae • Converts to sulfuric acid, sulfur trioxide, and sulfates when released into air • Dissolved in water • Absorbed into soil

30. Summary • Readily available gas • Terrorists may use to spread fear and disruption • Exposures as low as 5 ppm • Dryness of the nose and throat • Increase in airway restriction • Exposures at 100 ppm • Dangerous to life and health

31. Summary • Acute effects • Upper respiratory tract irritation • Rhinorrhea • Choking • Expectoration • Nosebleeds • Dysphagia • Oropharyngeal erythema and coughing • Chemical bronchopneumonia, pulmonary edema, cyanosis, asphyxia and death

32. Summary • No antidote • Care is supportive • Most common cause of death is asphyxiation