Winter haze in Delhi

Winter haze in Delhi

Subject: Environment

Section: Pollution

Context: Inefficient burning of biomass, like wood, leaves or stubble, in the early hours of the winter evenings could be the biggest contributor to the haze seen in and around Delhi during those months, a new research published in Nature Geoscience journal has revealed.

More on the News:

• The research by IIT-Kanpur, noticed a sharp increase in the presence of small particulate matter like soot that were the result of incomplete combustion of biomass. It also reported an extraordinarily rapid growth in the size of particles within a few hours’ time.
• The research throws new light on the process of formation of new particles that contribute to haze. Till now, the formation of new particles was known to happen mostly during the day.
• The study found a sudden rise in particulate matter coming in from burning of biomass in the evenings.

Haze:

• Haze is a type of atmospheric pollution characterized by a lack of visibility, caused by the presence of fine particles and droplets suspended in the air.

Sources of Haze:

1. Natural sources

• Wildfires: Smoke and ash generated by wildfires can travel long distances and contribute to regional haze.
• Dust storms: Wind-blown dust and sand can contribute to haze, particularly in arid regions.
• Volcanic eruptions: Volcanic ash and gases can be carried by wind over long distances and cause regional or even global haze events.
• Sea spray: Particles from ocean spray can be carried by wind and contribute to haze in coastal areas.

2. Human-made sources

• Fossil fuel combustion: Burning of coal, oil, and gas for energy and transportation releases a variety of pollutants, including particulate matter, sulfur dioxide, nitrogen oxides, and volatile organic compounds, which can contribute to haze formation.
• Industrial emissions: Factories and power plants can release large amounts of pollutants into the air, contributing to haze in nearby areas.
• Agricultural burning: Burning of crop residues and other agricultural waste can release smoke and other pollutants into the air, contributing to haze.

Impacts of Haze:

• Reduced visibility: Haze can reduce visibility, leading to safety hazards on roads, in transportation and aviation, and in outdoor activities.
• Respiratory problems: Fine particles and droplets in haze can irritate the lungs and exacerbate respiratory conditions such as asthma, bronchitis, and chronic obstructive pulmonary disease (COPD).
• Cardiovascular problems: Exposure to haze has also been linked to an increased risk of heart disease, stroke, and other cardiovascular problems.
• Environmental impacts: Haze can have significant impacts on the environment, including reduced plant growth and productivity, soil erosion, and increased water pollution.
• Climate change: Haze can contribute to climate change by trapping heat in the atmosphere and altering the earth’s radiation balance.

Smog

• Smog = smoke + fog (smoky fog) caused by the burning of large amounts of coal, vehicular emission and industrial fumes (Primary pollutants).
• Smog contains soot particulates like smoke, sulphur dioxide, nitrogen dioxide and other components.

Sulfurous smog

• Sulfurous smog results from a high concentration of Sulphur Oxides in the air and is caused by the use of sulfur-bearing fossil fuels, particularly coal.
• This type of smog is aggravated by dampness and a high concentration of suspended particulate matter in the air.

Photochemical smog

• Photochemical smog occurs most prominently in urban areas that have large numbers of automobiles (Nitrogen oxides are the primary emissions).
• Photochemical (summer smog) forms when pollutants such as nitrogen oxides (primary pollutant) and organic compounds (primary pollutants) react togetherin the presence of Sunlight. A gas called Ozone (Secondary pollutant) is formed.
• Nitrogen Dioxide +  Sunlight  +  Hydrocarbons  =  Ozone (Ozone in stratosphere it is beneficial, but near the earth’s surface it results in global warming as it is a greenhouse gas)
• The resulting smog causes a light brownish coloration of the atmosphere, reduced visibility, plant damage, irritation of the eyes, and respiratory distress.