Air Pollution and its Consequences

The air we respire is getting dangerously polluted day by day, making our survival difficult. in line with the WHO, quite 90% of the world's population breathes this dangerously polluted air, which kills 7 million people each year. Studies show that 85% of pollution is caused by the burning of fossil fuels and biogas. Besides some natural sources, human activities are primarily to blame for this elevated level of pollution. Microscopic air pollutants cross the body’s defense barriers and penetrate deep into bloodstreams and cause a spread of adverse health effects.

Criteria Air Pollutants 

According to the Clean Air Act, EPA set National Ambient Air Quality Standards (NAAQS) for 6 common air pollutants which also are referred to as “criteria air pollutants". These air pollutants include:

• Particulate matter
• Oxides of nitrogen
• Carbon monoxide
• Sulfur dioxide
• Ground-level ozone
• Lead

The adverse effects of those toxic air pollutants on the human population are described below:

Particulate Matter

The particulate matter could be a most harmful air pollutant that causes disastrous effects on the human population. It's a fancy mixture of soot, smoke, metals, nitrates, sulfates, dust, water, and tire rubber. The stuff contains microscopic solids or liquid droplets that are sufficiently small to enter in body and cause serious health problems when inhaled.

High concentrations of those air pollutants are typically emitted by sources like diesel vehicles and coal-fired power plants and also human activities like burning fossil fuels, incinerating wastes, and smelting metals contribute to their emission within the air. The material contains particles with diameters of 10 micrometers (μm) or smaller, called PM10, and intensely fine particles with diameters of 2.5 micrometers (μm) and smaller.

Health effects

The extent of penetration of those particles depends upon their size.

Inhalable coarse particles

Particles with a size greater than 10 mm never reach the lungs because they get trapped within the nose and throat. Particles of size between 5 and 10 mm may be far away from the throat by physical processes. But particles smaller than 5 mm reach the bronchial tubes.

Fine particles

Particles with size but 2.5 micrometers in diameter (PM2.5) are referred to as "fine" particles. due to their small size (approximately 1/30th the typical width of a person's hair), they will penetrate deeply into the lungs by crossing body defense barriers and ultimately enters the bloodstream where they affect both heart and lungs even causing carcinoma.

Long-term exposure

Long-term exposure to particulate pollution causes significant health effects including:

• Reduction of anticipation thanks to increasing in cardiopulmonary and carcinoma mortality
• Decrease lung function
• Premature deaths because of heart and lung diseases
• Development of bronchitis or chronic obstructive lung disease Short-term exposure to particulate pollution
• Increases the danger of lung disease causing asthma attacks and acute bronchitis
• Increase susceptibility to respiratory infections
• Cause heart attacks and arrhythmias in people already having cardiopathy

 

 

Gases

Oxides of nitrogen

Oxides of nitrogen include NO, NO2, and N2O which are collectively referred to as the NOx group. Exposure to high concentrations of those ambient air pollutants increases the danger of respiratory infections. Not only health effects, but it also affects crops and vegetation, as they reduce crop yield and plant growth efficiency.

The concentrations of those oxides between 0.2 and 0.6 ppm don’t cause any adverse effects on the human population. Out of these oxides of nitrogen, gas (NO2) may be a highly reactive gas that will reduce visibility and discolor fabrics. NO2 may be a traffic-related pollutant that primarily gets within the air from automobile motor engines like cars, trucks and buses, power plants, and off-road equipment.

 Health effects

Nitrogen dioxide penetrates deep into the lungs, which on short-term exposure causes respiratory diseases, coughing, wheezing, dyspnea, and bronchospasm.

Exposure to concentrations over 0.2 ppm produces adverse effects in humans, including eye, nose, or throat irritations, headache, chest pain, diaphoresis, and pulmonary edema.

Exposure at 2.0–5.0 ppm affects immune response-producing cells like T-lymphocytes, CD8+ cells, and NK cells, which produce defense against viruses.

People with asthma, also as children and therefore the elderly, are generally at greater risk for the health effects of NO2.

Concentrations over 2.0 ppm of NO2 may cause asthma, increase susceptibility to respiratory infections, and should also impair the sense of smell.

Carbon monoxide

This highly toxic pollutant is emitted thanks to incomplete combustion of carbon but naturally, it gets into the air from photochemical reactions within the troposphere, volcanoes, forest fires, etc. It's harmless at a standard concentration, of 0.1 ppm. 

• About 75% of CO is emitted by transport sectors.
• 10% because of residential wood burning.
• 15% by industrial processes.

 Health effects

Breathing air with a high concentration of CO reduces the quantity of oxygen because it's more binding affinity (240-270 times) to hemoglobin than oxygen. In return, it lowers the oxygen-carrying capacity of blood to critical organs of the body just like the heart and brain.

The poisoning symptoms of inhaling CO include headache, dizziness, weakness, nausea, vomiting, and, finally, loss of consciousness depending upon their length of exposure and concentration.

Competitive binding of CO increases the danger of getting hypoxia, ischemia, fatigue, headaches, and myocardial infections.

Sulfur dioxide

SO2 could be a highly reactive gas, produced by the burning of fuel by atomic power plants, volcanic eruptions, industrial processes, and combustion of fuel by heavy vehicles. According to EPA, 0.03ppm annual standard has been observed. Higher sulfur contents are metal extraction and emission of domestic fires.

 Health effects

• Exposure to SO2 causes redness on the skin, damage to the eyes, and respiratory problems including bronchitis and asthma.

• Long-term inhalation of SO2 results in carcinoma and cardiovascular diseases.

• SO₂ is responsible for acid rain and makes the soil acidic, not only affecting the building and plants but also crucial to human health.

• Acute symptoms of inhaling SO₂ include breathing difficulty, irritation in the nose, and minor blockage of respiratory valves.

 

 Ground-level Ozone

Ozone is formed when ultraviolet (UV) radiation creates oxygen free radicals by dissociating oxygen molecules. These free oxygen atoms collide with oxygen molecules forming ozone as a result. It is a 52% stronger oxidizing agent than chlorine.

Health effects

• Ozone adversely affects those who are diagnosed with lung cancer and asthma

• Short-term inhalation of ground-level ozone can cause redness and irritation on the skin.

• Long-term exposure to ozone can cause skin cancer, respiratory problems, and immunological disorders.

• Due to its oxidizing nature, it damages the respiratory tract and fluid lining of the cell membrane which leads to a high risk of DNA damage.

Lead

Lead is a heavy metal mostly evolved by lead batteries and smelters, waste incinerators, and metallurgical processes such as extraction and floatation of ores and minerals. According to EPA, 98% of lead in the air was removed from vehicles’ gasoline till 2014 but then volcanic eruption became the source of atmospheric lead.

• Use as a catalyst in chemical reactions
• Inhibits N-methyl-D-aspartate receptors in humans.
• Can replace calcium and other metals in the body

Health effects

• Long-term inhalation of lead severely affects the nervous, immune, and cardiovascular systems.

• It leads to respiratory dysfunction because hemoglobin is adversely affected by the lead in blood and the body becomes unable to carry oxygen.

• Accumulation of lead in bones and body causes harmful diseases and its removal from the body becomes very difficult.

• Major symptoms of the lead include headache, muscular and joint pain, constipation, and high blood pressure which leads to arthritis, anemia, and kidney transplantation.

• Minor exposure to lead in newly borns can cause neurological disabilities and mental retardation.