NOx | Oxides of Nitrogen| NO & NO2 Sources | OIZOM Academy
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NOx, apart from affecting human
NOx, apart from affecting human health and the environment itself, has the potential to produce “secondary pollutants” such as ozone, smog, nitric acid, and particulate matter. These pollutants have negative effects on health and the environment. NOx monitoring is an efficient way to prevent the accumulation of high levels of NOx as it helps detect the amount of NOX we are breathing in and alerts when a certain level is exceeded. This article covers information on nitrogen oxides, its sources, permissible levels in the ambient air, health and environmental impact, possible corrective measures, the need for nitrogen oxide monitors as well as different methods of NOx monitoring.
Nitrogen oxides in the Atmosphere
About 1% of the total NOX forms naturally in the atmosphere by lightning and some are produced by microbial processes in plants, soil, and water. It is typically produced from the reaction of nitrogen and oxygen when fossil fuels such as coal, oil, gas, or diesel are burned at high temperatures. From the nitrogen compounds released during combustion, generally, 10% is NO2 while 90% is NO.
Sources of NOx
NOx is primarily released in the air from the burning of fuel. Emissions from vehicles such as cars, trucks, buses, boats, airplanes, etc. are the largest source of nitrogen oxides, followed by emissions from power plants, diesel-powered heavy equipment, and other movable engines, industrial boilers, etc. Other sources of NOx include petrol and metal refining, food processing, and manufacturing industries such as the production of fertilizers. Kerosene or gas heaters or stoves also produce substantial amounts of NOx, which when placed in poorly ventilated spaces would result in a build-up of high levels.Permissible levels of NO2
Breathing air with a high concentration of NO2 can irritate the airways of the human respiratory system. Exposures for a short period can aggravate respiratory diseases, particularly asthma, leading to respiratory symptoms (such as coughing, wheezing, or difficulty breathing), hospital admissions, and visits to emergency rooms. Longer exposures may contribute to the development of asthma and potentially increase susceptibility to respiratory infections.
People with asthma are more affected as it can cause more frequent and more intense attacks. Children with asthma and the elderly with heart disease are more at risk.
Environmental Impact
Ozone (Smog) formation – NOx plays a major role in atmospheric reactions and produces ground-level ozone, one of the major components of smog which can have a significant impact on human health.
Acid rain – NOx interacts with water, oxygen, and other substances in the air to form nitric acid which falls on the earth in the form of rain, fog, snow, or dry particles. Acid rain harms sensitive ecosystems such as lakes and forests by making them acidic and unsuitable. It can corrode metals, fade fabrics and degrade rubber and cause deterioration of cars, buildings, historical monuments, etc.
Particulate Matter: NOx contributes to the formation of particulate matter which causes health concerns including problems in breathing and the respiratory system by penetrating deeply into the sensitive parts of the lungs resulting in respiratory diseases.
Water Quality Deterioration: Increased absorption of NOx in the water bodies upsets the chemical balance of nutrients leading to oxygen depletion in the water bodies.
Visibility Impairment: The nitrate particles that result from NOx can block the transmission of light, making the air hazy and difficult to see through.
Possible corrective measures
The primary step is NOx monitoring to identify the areas with high NO2 and NO levels or areas where air quality does not meet the NOx national standards. In addition to this following corrective measures can be taken:
Electrochemical method for NOx monitoring
NOx monitors working on the electrochemical principle are operated based on the diffusion of nitrogen dioxide and nitric oxide gas into the respective sensor which results in the production of electrical signals proportional to the NO2 and NO concentration respectively. It allows accurate measurement of even low concentrations of NOx, which is essential in NO2 monitoring and NO monitoring for the ambient air.
NOx monitoring is an efficient way to prevent the accumulation of high levels of NOx as it helps detect the amount of NOX we are breathing in and alerts when a certain level is exceeded.
Real-time monitoring of NOx levels helps in calculating air quality index to deliver health advisories as well as formulating an action plan to meet standards.
Nitrogen oxides in the Atmosphere
About 1% of the total NOX forms naturally in the atmosphere by lightning and some are produced by microbial processes in plants, soil, and water. It is typically produced from the reaction of nitrogen and oxygen when fossil fuels such as coal, oil, gas, or diesel are burned at high temperatures. From the nitrogen compounds released during combustion, generally, 10% is NO2 while 90% is NO.
Sources of NOx
NOx is primarily released in the air from the burning of fuel. Emissions from vehicles such as cars, trucks, buses, boats, airplanes, etc. are the largest source of nitrogen oxides, followed by emissions from power plants, diesel-powered heavy equipment, and other movable engines, industrial boilers, etc. Other sources of NOx include petrol and metal refining, food processing, and manufacturing industries such as the production of fertilizers. Kerosene or gas heaters or stoves also produce substantial amounts of NOx, which when placed in poorly ventilated spaces would result in a build-up of high levels.Permissible levels of NO2
Breathing air with a high concentration of NO2 can irritate the airways of the human respiratory system. Exposures for a short period can aggravate respiratory diseases, particularly asthma, leading to respiratory symptoms (such as coughing, wheezing, or difficulty breathing), hospital admissions, and visits to emergency rooms. Longer exposures may contribute to the development of asthma and potentially increase susceptibility to respiratory infections.
People with asthma are more affected as it can cause more frequent and more intense attacks. Children with asthma and the elderly with heart disease are more at risk.
Environmental Impact
Ozone (Smog) formation – NOx plays a major role in atmospheric reactions and produces ground-level ozone, one of the major components of smog which can have a significant impact on human health.
Acid rain – NOx interacts with water, oxygen, and other substances in the air to form nitric acid which falls on the earth in the form of rain, fog, snow, or dry particles. Acid rain harms sensitive ecosystems such as lakes and forests by making them acidic and unsuitable. It can corrode metals, fade fabrics and degrade rubber and cause deterioration of cars, buildings, historical monuments, etc.
Particulate Matter: NOx contributes to the formation of particulate matter which causes health concerns including problems in breathing and the respiratory system by penetrating deeply into the sensitive parts of the lungs resulting in respiratory diseases.
Water Quality Deterioration: Increased absorption of NOx in the water bodies upsets the chemical balance of nutrients leading to oxygen depletion in the water bodies.
Visibility Impairment: The nitrate particles that result from NOx can block the transmission of light, making the air hazy and difficult to see through.
Possible corrective measures
The primary step is NOx monitoring to identify the areas with high NO2 and NO levels or areas where air quality does not meet the NOx national standards. In addition to this following corrective measures can be taken:
Electrochemical method for NOx monitoring
NOx monitors working on the electrochemical principle are operated based on the diffusion of nitrogen dioxide and nitric oxide gas into the respective sensor which results in the production of electrical signals proportional to the NO2 and NO concentration respectively. It allows accurate measurement of even low concentrations of NOx, which is essential in NO2 monitoring and NO monitoring for the ambient air.
NOx monitoring is an efficient way to prevent the accumulation of high levels of NOx as it helps detect the amount of NOX we are breathing in and alerts when a certain level is exceeded.
Real-time monitoring of NOx levels helps in calculating air quality index to deliver health advisories as well as formulating an action plan to meet standards.
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