Diseases Caused by Oxides of Nitrogen

1. Introduction and Definitions

Oxides of nitrogen (NOx) refer to a group of highly reactive gases, including nitrogen dioxide (NO2) and nitric oxide (NO). These gases are produced from the reaction of nitrogen and oxygen during combustion processes. Exposure to NOx can lead to severe respiratory and cardiovascular diseases, making it a significant concern for occupational health. This article aims to provide comprehensive information on diseases caused by oxides of nitrogen, targeting occupational health nurses and doctors.

2. Agent Causes the Disease

Exposure to oxides of nitrogen primarily occurs through inhalation of the gases produced during combustion. The main sources of NOx in occupational settings include:

  • Combustion Engines: Vehicles, generators, and machinery that burn fossil fuels.
  • Industrial Processes: Manufacturing processes that involve high-temperature combustion, such as steel production and chemical manufacturing.
  • Power Plants: Burning of coal, oil, or natural gas for electricity generation.
  • Agricultural Operations: Use of fertilizers that release NOx.

3. Workers at Risk of This Disease

Several occupations and tasks put workers at higher risk of exposure to oxides of nitrogen, including:

  • Industrial Workers: Involved in manufacturing processes with high-temperature combustion.
  • Construction Workers: Operating diesel-powered machinery and vehicles.
  • Farmers and Agricultural Workers: Using nitrogen-based fertilizers.
  • Power Plant Workers: Exposed to emissions from combustion processes.
  • Firefighters: Exposure to combustion products during firefighting.
  • Laboratory Technicians: Working with nitric acid and other nitrogen compounds.

4. Symptoms

Symptoms of diseases caused by oxides of nitrogen exposure can vary depending on the level and duration of exposure:

  • Acute Exposure: Symptoms include coughing, throat irritation, shortness of breath, chest pain, and wheezing. Severe exposure can lead to pulmonary edema and acute respiratory distress syndrome (ARDS).
  • Chronic Exposure: Long-term exposure can cause chronic bronchitis, emphysema, reduced lung function, and an increased risk of respiratory infections. There is also evidence linking chronic exposure to cardiovascular diseases.

5. Diagnosis

Diagnosing diseases caused by oxides of nitrogen involves a combination of clinical evaluation, occupational exposure assessment, and specific tests:

  • Medical History and Physical Examination: Detailed assessment of the patient's work history and symptoms.
  • Pulmonary Function Tests: To assess lung function and detect obstructive or restrictive patterns.
  • Chest X-rays or CT Scans: Imaging to detect lung damage, such as inflammation or fibrosis.
  • Blood Tests: Measuring levels of nitrogen compounds and markers of inflammation.
  • Bronchoscopy: To examine the airways and collect samples for further analysis if necessary.

6. Treatment

Treatment for diseases caused by oxides of nitrogen focuses on managing symptoms and preventing further exposure:

  • Remove from Exposure: Immediate removal from the source of NOx exposure is crucial.
  • Symptomatic Treatment: Providing medications to manage respiratory symptoms, such as bronchodilators, corticosteroids, and oxygen therapy for severe cases.
  • Supportive Care: Including hydration, rest, and monitoring of respiratory and cardiovascular function.
  • Long-term Monitoring: Regular follow-up to monitor lung function, manage chronic respiratory conditions, and assess overall health status.

7. Prevention

Preventing diseases caused by oxides of nitrogen involves implementing strict control measures in the workplace:

  • Engineering Controls: Using local exhaust ventilation, emission controls, and proper maintenance of combustion equipment to reduce NOx levels.
  • Work Practices: Implementing safe work practices such as proper handling and storage of nitrogen-based compounds, and avoiding exposure to exhaust fumes.
  • Personal Protective Equipment (PPE): Providing and ensuring the use of appropriate respirators, protective clothing, and gloves.
  • Health Surveillance: Regular health screenings, including pulmonary function tests and respiratory assessments for workers exposed to NOx.
  • Education and Training: Informing workers about the hazards of oxides of nitrogen and safe work practices to minimize exposure.

By recognizing the hazards of oxides of nitrogen exposure and applying effective preventive strategies, occupational health professionals can substantially lower the occurrence of related illnesses and improve the overall health and safety of workers.

Workplace Exposure Limits:

Nitrogen dioxide (NO₂):

  • OSHA PEL:
    • Time-Weighted Average (TWA): 5 ppm (9 mg/m³).
    • Short-Term Exposure Limit (STEL): 5 ppm (9 mg/m³).
  • NIOSH REL: Short-Term Exposure Limit (STEL) of 1 ppm.