Comprehensive Study Notes on Smog and Environmental Quality and Environmental Standards

Introduction to Smog

Smog is a specific form of air pollution comprised of tiny particles suspended in the air. The term and its characteristics are defined as follows:

• Etymology and Origin: The term "smog" was first coined in 1905 by Dr. Henry Antoine Des Voeux in a research paper. It is a portmanteau of the words "smoke" and "fog."
• Composition: It consists of a hazy mixture of heavily polluted air. This mixture is primarily formed by the emission of sulfur dioxide ($SO_2$) and various aerosols resulting from the combustion of fossil fuels, specifically coal and petroleum oil.
• Formation Conditions: Smog typically forms during the winter months under specific meteorological conditions, including calm winds, stable atmospheric layers, and moist air.
• Modern Application: While originally describing smoke and fog, the term is now used for any severe urban air pollution that restricts visibility and causes respiratory health issues.

Types of Smog

Smog is categorized into two distinct types based on its chemical composition and the conditions under which it forms: Industrial Smog and Photochemical Smog.

Industrial Smog (Classical Smog)

• Common Names: Also known as "London Smog" or "Sulphurous Smog."
• Formation Environment: Occurs in areas with high water vapor and high levels of sulfur emissions, typically from coal combustion.
• Chemical Process: Sulfur particles dissolve into atmospheric water droplets to form sulfuric acid ($H_2SO_4$). Coal soot contributes to darkening the atmosphere.
• Appearance: Characterized by a dark brownish or grayish color.
• Constituents:
  • Soot
  • Fly ash
  • Sulfur dioxide ($SO_2$)
  • Sodium chloride ($NaCl$)
  • Calcium sulfate ($CaSO_4$) particles

Photochemical Smog

• Common Names: Frequently referred to as "L.A. type smog" (Los Angeles smog).
• Formation Mechanism: This haze is created when solar radiation (sunlight) triggers chemical reactions between primary pollutants, specifically nitrogen oxides ($NO_x$) and volatile organic compounds (VOCs). These pollutants are primarily emitted by automobiles, industrial factories, and power plants.
• Chemical Progress: The reaction leads to the creation of secondary pollutants.
• Appearance: Typically exhibits a more brownish color.
• Constituents:
  • Nitrogen oxides ($NO_x$)
  • Ozone ($O_3$)
  • Carbon monoxide ($CO$)
  • Hydrocarbons ($HC$)
  • Aldehydes (eye irritants)
  • Peroxyacetyl nitrates (PANs)
  • Trace free radical hydrocarbons
  • Occasional sulfuric acid ($H_2SO_4$)
• Geographic Examples: Highly prevalent in large metropolitan areas such as Los Angeles and Mexico City.

Effects and Remedies of Smog

Environmental and Health Effects

• Toxicity: Major constituents of smog are identified as powerful poisons, with the exception of carbon dioxide ($CO_2$).
• Visibility: Smog significantly reduces visibility and creates an aesthetically unappealing haze on the horizon.
• Respiratory Distress: Smog causes irritation to the eyes, nose, throat, and chest. It makes breathing difficult by "choking" the lungs, a condition particularly dangerous for individuals with asthma.
• Specific Irritants: Eye irritation is specifically attributed to Peroxyacetyl nitrates (PANs) and trace free radical hydrocarbons, rather than ozone ($O_3$).
• Agriculture and Animals: Smog pollutes and damages crops via "blighting" plants. It is also linked to health problems in domestic pets and farm livestock.
• Structural Damage: Smog causes corrosive damage to both buildings and vehicles.

Remedies and Mitigation Strategies

• Energy Conservation: Conserving energy at home, work, and across all daily activities.
• Product Selection: Prioritizing "ENERGY STAR" labeled equipment and using environmentally safe paints and cleaning products.
• Transportation: Utilizing carpooling, public transit, biking, or walking. Ensure vehicle tires are properly inflated to maximize efficiency.
• Fuel Handling: Choosing portable gasoline containers labeled as "spill-proof."
• Waste Management: Mulching or composting leaves and yard waste instead of burning them. Avoid burning trash and other materials.

Air Quality Standards and the CPCB

Central Pollution Control Board (CPCB)

• Status: An autonomous body functioning under the Ministry of Environment, Forest and Climate Change (MoEF&CC).
• Establishment: Established in 1974 under the Water (Prevention and Control of Pollution) Act, 1974.
• Mandate:
  • Coordinates activities with State Pollution Control Boards (SPCBs) and Pollution Control Committees (PCCs).
  • Implements legislation regarding environmental pollution prevention.
  • Advises the Central Government and Union Territories on matters of air and water pollution.
  • Empowered by the Air Act to establish Air Quality Parameters and standards.

Air Quality Index (AQI)

AQI is a numerical scale used by government agencies to communicate the current or forecast level of air pollution to the public.

• Pollutants Measured: CPCB measurement is based on 8 specific pollutants:
  1. Particulate Matter 10 ($PM_{10}$)
  2. Particulate Matter 2.5 ($PM_{2.5}$)
  3. Sulfur dioxide ($SO_2$)
  4. Nitrogen dioxide ($NO_2$)
  5. Ozone ($O_3$)
  6. Carbon monoxide ($CO$)
  7. Ammonia ($NH_3$)
  8. Lead ($Pb$)
• Units: Measured in micrograms per cubic meter ($\mu g/m^3$), or milligrams per cubic meter ($mg/m^3$) specifically for $CO$.
• Cities Monitored: Currently launched for 10 Indian cities: Delhi, Agra, Kanpur, Lucknow, Varanasi, Faridabad, Ahmedabad, Chennai, Bangalore, and Hyderabad.

CPCB AQI Categories

International Air Standards (US Clean Air Act)

In the United States, the Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards (NAAQS) for 6 pollutants ($CO$, Lead, $NO_2$, $O_3$, $PM$, and $SO_2$):

1. Primary Standards: Designed for public health protection, focusing on sensitive populations like asthmatics, children, and the elderly.
2. Secondary Standards: Focused on public welfare, protecting against decreased visibility and damage to animals, crops, vegetation, and infrastructure.

Water Quality Standards: Physical Parameters

Water quality is defined by its physical, chemical, and biological properties, based on its intended use (e.g., drinking water requires the highest purity, while irrigation allows lower standards).

1. Colour

• Pure water is colorless.
• Apparent Color: Caused by suspended material.
• True/Real Color: Color that remains after the removal of suspended material, caused by dissolved materials from decayed organic matter (vegetation) or inorganic matter (soil, stone, rock).
• Impact: Primarily aesthetic; not inherently a health risk.
• Measurement: Measured by a Tintometer.
• Permissible Limit: $15 \text{ Hazen units}$.

2. Taste and Odour

• Pure water is tasteless and odorless.
• Artificial Causes: Chlorination.
• Natural Causes: Inorganic salts ($NaCl$, $KCl$) provide taste; compounds like hydrogen sulfide ($H_2S$) provide both taste and odor.
• Implication: Some taste/odor-causing compounds can be toxic; drinking water must be tasteless and odorless.

3. Total Suspended Solids (TSS)

• Definition: Solids trapped by a filter. Particles are generally larger than $2 \, \mu m$.
• Components: Silt, decaying plant/animal matter, industrial waste, and sewage.
• Consequences:
  • Blocks sunlight, slowing photosynthesis in submerged vegetation.
  • Reduces dissolved oxygen ($DO$) as plants die and bacteria decompose them, leading to fish kills.
  • Increases surface water temperature as particles absorb solar heat.

4. Turbidity

• Definition: The cloudiness of water; a measure of light penetration.
• Causes: Clay, silt, organic material, plankton.
• Environmental Impact: Prevents light from reaching deeper layers, affecting photosynthetic organisms at the bottom.
• Measurement: Measured by a Nephelometric Turbidimeter in NTU ($\text{Nephelometric Turbidity Units}$) or TU.
• Standards: Drinking water should be less than $5 \, \text{NTU}$. Visibility to the average person occurs above $5 \, \text{NTU}$. Muddy water can exceed $100 \, \text{NTU}$.
• Groundwater: Usually has low turbidity due to natural soil filtration.

5. Temperature

• Domestic Limit: Desirable range is $10^\circ C$ to $20^\circ C$.
• Biological Impact: Governs the types of aquatic life present and influences metabolic rates.
• Chemical Impact: Regulates the maximum $DO$ concentration (warmer water holds less oxygen) and influences the rate of chemical and biological reactions.

Water Quality Standards: Chemical and Biological Parameters

Chemical Parameters

• Total Dissolved Solids (TDS): Particles between $10^{-3} \, \mu m$ and $10^{-5} \, \mu m$. Impart color, taste, and toxicity. Removed via reverse osmosis (RO) or electrodialysis.
• pH: The negative logarithm of $H^+$ ion concentration. Measure of acidity/alkalinity ($0-14$ range). Potable water range: $6.5$ to $8.5$.
• Acidity: Capacity to neutralize $OH^-$ ions. Caused by minerals and dissolved $CO_2$. Causes corrosion in metal pipelines.
• Alkalinity: Capacity to neutralize $H^+$ ions. Caused by bicarbonates, carbonates, and hydroxides. Imparts a bitter taste.
• Hardness: The soap-destroying property of water.
  • Temporary: Carbonates and bicarbonates of $Ca$ and $Mg$.
  • Permanent: Sulfates, chlorides, and nitrates of $Ca$ and $Mg$.
  • Impact: Excessive soap consumption, boiler scale deposits. Groundwater is typically harder than surface water.
• Chlorides: From sea water intrusion, industrial, and domestic waste ($CaCl_2$, $NaCl$, $MgCl_2$). Imparts salty taste.
• Fluorides: From sedimentary/igneous rocks.
  • Beneficial: Small amounts prevent dental cavities.
  • Toxic: Excess amounts cause discoloration of teeth (Fluorosis) and harm humans/animals.
• Metals:
  • Toxic: Arsenic ($As$), Cadmium ($Cd$), Chromium ($Cr$), Lead ($Pb$), Mercury ($Hg$).
  • Sodium: Excess causes bitter taste and cardiac/kidney health hazards.
  • Iron/Manganese: Impart color even in small quantities.
• Organic Matter: Utilizes $DO$ for degradation, decreasing oxygen levels for the aquatic ecosystem.

Biological Parameters

Pathogenic and non-pathogenic bacteria in water are collectively termed the B-coli group.

• Disease-causing agents:
  • Bacteria: Cholera, diarrhea, typhoid, jaundice.
  • Protozoa: Amebic dysentery, giardiasis.
  • Viruses: Hepatitis, meningitis, poliomyelitis.

Standard-Setting Bodies

1. Indian Standard Institution (ISI)
2. World Health Organization (WHO)
3. Indian Council of Medical Research (ICMR)
4. United States Public Health Services (USPHS)

Questions & Discussion

Q: How do you control noise pollution? (Review of previous session)

• Note: The transcript lists this as a reflection point for students based on previous lessons covering Noise and Radioactive pollution.

Q: Have you heard the term smog?

• Introduction to the day's concept through an opening image/question.

Q: What are the differences between classical and photochemical smog? (Think-pair-share Activity)

• Classical (Industrial) is coal-based, gray/brown, involves $SO_2$/soot, and is common in London-type climates.
• Photochemical is automobile-based, brownish, involves sunlight + $NO_x$ + VOCs, and is common in L.A.-type climates.

Q: Write the effects of smog.

• Includes respiratory issues, visibility reduction, plant blighting, and building corrosion.

Q: How can you measure water quality standards?

• Measurement is conducted through physical (Tintometer, Turbidimeter), chemical (pH scale, titration for hardness/acidity), and biological (pathogen testing) parameters.