Nitrogen dioxide (NO2) is a reddish-brown gas with a characteristic sharp, biting odor. It is one of a group of gases known as nitrogen oxides (NOx). NO2 is primarily produced from the burning of fossil fuels in vehicles and power plants, and can also be generated from natural sources like wildfires and lightning.
NO2 is a known respiratory irritant. Short-term exposure can lead to increased respiratory symptoms, such as coughing and shortness of breath, and reduced lung function. Long-term exposure can exacerbate chronic respiratory diseases like asthma and may even contribute to the development of respiratory infections. Additionally, there is growing evidence that prolonged exposure to NO2 may have cardiovascular effects.
NO2 does not only affect human health but also the environment. It plays a significant role in the formation of ground-level ozone and fine particulate matter (PM2.5), both of which have adverse health and environmental effects. NO2 can also contribute to the formation of acid rain, which can harm ecosystems, including forests, soils, and water bodies.
Exposure to NO2 can be measured using air quality monitors that detect the concentration of this gas in the air. These measurements are typically expressed in parts per billion (ppb) or parts per million (ppm). Regulatory agencies, such as the
EPA, set air quality standards to limit NO2 exposure and protect public health.
The EPA has established National Ambient Air Quality Standards (NAAQS) for NO2 to protect public health and the environment. The current standards include a primary (health-based) standard of 100 ppb for a 1-hour average concentration and an annual average concentration of 53 ppb. Other countries and regions have their own regulatory standards, which may vary.
There are several strategies to reduce NO2 emissions, including:
Implementing stricter emissions standards for vehicles and industrial processes.
Promoting the use of cleaner fuels and renewable energy sources.
Enhancing public transportation and encouraging the use of electric vehicles.
Improving energy efficiency in homes, buildings, and industries.
Occupational exposure limits (OELs) for NO2 are set by various organizations to protect workers from harmful exposure. For example, the
OSHA has set a permissible exposure limit (PEL) of 5 ppm for an 8-hour time-weighted average (TWA). The
ACGIH recommends a threshold limit value (TLV) of 3 ppm as a TWA for a normal 8-hour workday and a 40-hour workweek.
Symptoms of NO2 poisoning can range from mild to severe, depending on the level and duration of exposure. Acute exposure to high levels can cause:
Eye, nose, and throat irritation
Coughing and shortness of breath
Chest pain
Nausea
Fluid buildup in the lungs (pulmonary edema)
Chronic exposure can lead to persistent respiratory problems and may increase the risk of developing asthma and other respiratory diseases.
In case of exposure to NO2:
Move to an area with fresh air immediately.
Seek medical attention if you experience severe symptoms, such as difficulty breathing or chest pain.
Use protective equipment, such as masks and respirators, if you are in an environment with high levels of NO2.
Employers should ensure that workers are trained on the hazards of NO2 and equipped with appropriate safety measures.
