After the Second World War, rapid population growth and unprecedented economic development led to large-scale environmental degradation. Consequences included deforestation, air, water, and soil pollution, ozone depletion, species extinction, and global warming. The rise in plastic waste, both biodegradable and non-biodegradable, along with excess nitrogen and phosphorus from fertilizers and the extensive use of pesticides and insecticides, has deteriorated Earth's natural balance, creating ecological disequilibrium.
This destruction was worsened due to insufficient awareness and weak environmental monitoring systems. Strict adherence to environmental standards is essential to mitigate further deterioration and restore ecological stability.
Environmental standards refer to the maximum allowable concentrations of harmful pollutants released into the environment to maintain health and environmental quality. These standards are typically set as numerical values and permissible ranges by governments and enforced by regulatory bodies.
They differ based on the geographical location and country-specific policies. The purpose of these standards is to regulate pollutant concentration in land, water, and air by defining acceptable emission/discharge levels per unit of production, time, or energy used.
Primary standards are intended to protect human health, particularly vulnerable populations like children and the elderly. These cover aspects like drinking water and air quality.
Secondary standards focus on environmental protection and human welfare, targeting issues like reduced visibility, damage to flora, fauna, and buildings.
Regions are classified as attainment areas (meeting these standards) or non-attainment areas (failing to meet them).
Ambient standards represent the concentration of pollutants in surrounding environments. Achieving these requires tracking emission sources. Expressed as average concentrations over time, examples include National Ambient Air Quality Standards set for 8-hour and 24-hour periods by the Central Pollution Control Board (CPCB).
These standards limit emissions from specific sources like industries. Formats include:
Source standards define pollutant levels directly at the point of origin. Examples include power plant emissions and noise pollution from generators.
These are exposure-based standards related to the polluter’s outcome. For instance:
Biological standards monitor pollutant levels in tissues and fluids. Though accurate, they are challenging due to the need for personal samples. Example: impact on aquatic ecosystems from industrial discharge into lakes.
Technology standards require specific technologies or practices during production to minimize pollution. This “technology forcing” approach compels industries to adopt cleaner technologies and comply with regulatory expectations.
At the international level, environmental norms are mostly guided by the World Health Organization (WHO). These include:
WHO guidelines form the basis for many national regulations and emphasize preventive risk management from water source to consumer. These are enforced via independent surveillance and implementation of safety plans.
All countries also maintain their own environmental standards, adapted from WHO’s framework.
India adheres to standards set by various national bodies such as the Central Pollution Control Board (CPCB) and Bureau of Indian Standards (BIS).
The CPCB has notified National Ambient Air Quality Standards (NAAQS) for 12 key pollutants: PM10, PM2.5, CO, SO₂, NO₂, NH₃, O₃, Lead, Arsenic, Nickel, Benzene, and Benzo(a)Pyrene. These standards help track pollution levels and shape policy interventions for air quality improvement.
Additionally, the Government of India has established 115 emission/effluent standards across 104 industrial sectors and 32 ambient pollutant categories.
The BIS issued specifications under IS–10500, revised in 2012, for drinking water. Known as the Uniform Drinking Water Quality Monitoring Protocol, it defines two levels:
Water exceeding these thresholds is deemed unfit for human consumption.
Environmental monitoring is a scientific and technical process used to observe and collect data on environmental conditions to assess trends over time.
It plays a crucial role in determining whether environmental quality is improving or deteriorating due to anthropogenic activities.
Environmental monitoring supports policy development, regulation of environmental quality standards and laws, and offers baseline information to policymakers, international forums, and the general public.
This systematic sampling involves air, water, soil, and biota to analyze structure and composition of environmental components and develop mitigation and management plans.
It helps assess risks and create strategies to control or reduce negative environmental impacts from human activities.
To develop environmental standards based on legislation, technical guidelines, and expert recommendations concerning biodiversity, air and water quality, soil fertility, and natural heritage.
To identify and alert polluters, enabling corrective actions and maintenance of environmental quality.
To regulate pollution levels that could harm human health or the physical environment.
To gather toxicological information on chemical substances and their environmental impacts.
To assist in developing and implementing an Environmental Management Plan (EMP) and conducting Environmental Impact Assessments (EIA).
To monitor effectiveness of mitigation measures before, during, and after project implementation.
Major indicators include air, water, soil quality, noise levels, waste management, and environmental composition.
To empower communities in environmental conservation and sustainability efforts.
To guide development activities to avoid ecological damage and promote sustainable development.
To maintain ecological balance, regulate resource use, and prevent environmental threats.
To balance economic development with ecological preservation by promoting green technologies.
Monitoring involves three core activities:
Field data collection at designated sites by agencies like Central Pollution Control Board (CPCB) and State Pollution Control Board (SPCB).
Applies to monitoring of air, water, soil, and noise pollution.
Laboratory analysis and real-time automated monitoring instruments at sample sites.
Involves advanced models and systems applied mainly in countries with strong environmental governance.
These models serve as additional protection tools in developed regions and offer new opportunities for less developed countries.
Utilizes satellites in geostationary and low-earth orbits to monitor global environmental changes.
Offers real-time data for atmospheric, hydrological, and ecological monitoring.
Atmospheric monitoring includes tracking aerosols, particulate matter, pollution gases, and greenhouse gases.
Hydrological monitoring involves water quality, oil spills, pollution, and safety assessment of drinking water.
Ecological monitoring tracks wildlife habitats, biodiversity, soil contamination, and environmental damage from activities like mining.
Ambient air refers to the natural atmospheric air in its uncontaminated state, free from significant air-borne pollutants.
Its typical composition includes approximately 78% nitrogen, 21% oxygen, and 1% other gases like carbon dioxide, helium, methane, argon, and hydrogen.
Clean air is essential for maintaining public health, though it is rarely free of natural or man-made pollutants in real-world conditions.
Due to increasing anthropogenic activities, pollutants like carbon monoxide (CO), carbon dioxide (CO₂), sulphuric acid (H₂SO₄), and greenhouse gases are rising continuously in the atmosphere.
This growing pollution significantly affects air quality and health outcomes.
Air quality standards are legal thresholds for pollutants in ambient air, defined over specific time periods to protect public and environmental health.
They regulate permissible exposure levels for individuals and ecosystems.
India’s national standards were formulated under the Environment Protection Act, 1986 for pollutants like TSPM, PM10, SO₂, and NO₂.
These are categorized based on land use: residential, industrial, and sensitive areas.
The Central Pollution Control Board (CPCB) developed these standards under powers granted by the Water Act (1974) and Air Act (1981), and they were officially notified by the Ministry of Environment and Forests.
Refer to the CPCB official website: www.cpcb.nic.in for updated information.
As per gazette notification G.S.R826(E), dated 16.11.2009, the revised National Ambient Air Quality Standards were issued by amending the Environment (Protection) Rules, 1986.
Below is the summary of the pollutant limits defined by CPCB under different land use zones:
| Pollutant | Time Weighted Average | Industrial, Residential, Rural Areas (µg/m³) | Ecologically Sensitive Areas (µg/m³) |
|---|---|---|---|
| Sulphur Dioxide (SO₂) | Annual / 24 hours | 50 / 80 | 20 / 80 |
| Nitrogen Oxide (NO₂) | Annual / 24 hours | 40 / 80 | 30 / 80 |
| Particulate Matter 10 (PM₁₀) | Annual / 24 hours | 60 / 100 | 60 / 100 |
| Particulate Matter 2.5 (PM₂.₅) | Annual / 24 hours | 40 / 60 | 40 / 60 |
| Ozone (O₃) | 8 hours / 1 hour | 100 / 180 | 100 / 180 |
| Lead (Pb) | Annual / 24 hours | 0.5 / 1.0 | 0.5 / 1.0 |
| Carbon Monoxide (CO) | 8 hours / 1 hour | 2.0 / 4.0* | 2.0 / 4.0* |
| Ammonia (NH₃) | Annual / 24 hours | 100 / 400 | 100 / 400 |
Source: Central Pollution Control Board, MOEF&CC, Government of India
*Note: Carbon Monoxide (CO) is measured in mg/m³
Water is a vital element in the biosphere, essential to all forms of life.
It enables the movement, circulation, and cycling of nutrients through the atmosphere, lithosphere, and hydrosphere.
Historically, faecal pollution in water led to outbreaks of waterborne diseases, devastating entire populations in several urban regions worldwide.
Primary sources of water pollution include:
Water pollutants can be broadly categorized as:
The World Health Organization (WHO) provides international guidelines for water quality and human health standards.
These norms are developed through global consultations involving WHO member states (including India), national authorities, and international experts.
Below are the maximum permissible limits set by USPH, WHO, and European Standards for various water quality parameters:
| Parameter | USPH Standard | WHO Standard | European Standard (mg/L) |
|---|---|---|---|
| pH | 6–8.5 | 6.5–9.2 | 6.5–8.5 |
| Specific Conductance (µm/cm⁻¹) | – | – | 400 |
| Arsenic | 0.05 | 0.05 | – |
| Ammonia | 0.5 | 0.5 | – |
| BOD | 5.0 | 6.0 | – |
| Boron | – | 1.0 | – |
| Calcium | – | 100 | 100 |
| Cadmium | 0.01 | 0.01 | – |
| Chromium | – | 0.05 | 0.05 |
| Copper | – | 1.0 | 1.5 |
| Chloride | 250 | 500 | 25 |
| Cyanide | – | 0.05 | 0.05 |
| COD | – | 4.0 | 10.0 |
| Iron | – | 0.3 | 1.0 |
| Lead | – | 0.05 | 0.1 |
| Magnesium | – | 30 | 150 |
| Manganese | – | 0.05 | 0.5 |
| Mercury | – | 0.001 | 0.001 |
| Nitrate + Nitrite | – | 10 | 45 |
| Phenol | – | 0.001 | 0.002 |
| PAH (Polynuclear Aromatic Hydrocarbons) | – | 0.002 | – |
| Pesticides (Total) | – | 0.005 | 0.005 |
| E. coli (per 100 mL) | 100 | 10 | – |
| Total Hardness (CaCO₃) | – | – | 500 |
| Total Dissolved Solids | – | 500 | – |
Source: De, A.K., 2003
The Bureau of Indian Standards (BIS) has set two key limits:
Refer to BIS Code IS 1500-2012 for full details on drinking water standards in India.
| Sl. No. | Parameter | Acceptable Limit | Permissible Limit |
|---|---|---|---|
| 1 | pH Value | 6.5–8.5 | No relaxation |
| 2 | Turbidity (NTU) | 1 | 5 |
| 3 | Total Hardness (as CaCO₃) | 200 | 600 |
| 4 | E. coli (per 100 mL) | Shall not be detectable in any 100 mL sample | |
| 5 | Total Iron (as Fe) | 0.3 | No relaxation |
| 6 | Taste | Agreeable | |
| 7 | Odour | Agreeable | |
Source: Bureau of Indian Standards, 2012