Ambient Air Quality Monitoring under National Ambient Air Quality Standards (NAAQS), 2019

Ambient Air Quality Monitoring under National Ambient Air Quality Standards (NAAQS), 2019

Introduction

Air quality directly influences the health and well-being of humans, plants, and animals. Poor air quality leads to respiratory and cardiovascular diseases, damages ecosystems, and affects visibility and climate. To evaluate and improve air quality, the Central Pollution Control Board (CPCB) under the Ministry of Environment, Forest and Climate Change (MoEFCC) oversees Ambient Air Quality Monitoring across India.

This monitoring is guided by the National Ambient Air Quality Standards (NAAQS) notified in 2009 and implemented through the National Air Quality Monitoring Programme (NAMP). The 2019 CPCB Report presents a detailed assessment of air quality across the country based on data from 804 monitoring stations covering 344 cities in 28 States and 6 Union Territories.

Objectives of NAAQS

According to the CPCB (2019), the National Ambient Air Quality Standards aim to:

  • Define acceptable air quality levels that ensure public health protection.
  • Serve as a uniform national benchmark for air quality comparison.
  • Identify cities and areas exceeding permissible pollutant levels.
  • Support the development of pollution prevention and control measures.

Evaluate the natural cleansing capacity of the atmosphere

Applicability

The NAAQS, 2019 are applicable to:

  • All Indian regions—industrial, residential, rural, and ecologically sensitive areas.
  • Monitoring and regulatory agencies, including CPCB, SPCBs, PCCs, NEERI, and local authorities.
  • Industries and infrastructure projects that must demonstrate compliance with these standards in Environmental Impact Assessments (EIAs).
  • Public health and research institutions utilizing air quality data for environmental and epidemiological studies.

Parameters Monitored

Under NAMP, the CPCB monitors 12 pollutants, including core and supplementary parameters.

Core Pollutants (monitored at all locations):

  1. Sulphur Dioxide (SO₂)
  2. Nitrogen Dioxide (NO₂)
  3. Particulate Matter (PM₁₀)

Meteorological parameters such as wind speed, wind direction, relative humidity, and temperature are also recorded to interpret pollutant dispersion.

Ambient Air Quality Standards

Pollutant

Averaging Period

Concentration in Ambient Air (µg/m³)

 

Industrial, Residential, Rural & Other Areas

SO₂

Annual

50

24-hourly

80

NO₂

Annual

40

24-hourly

80

PM₁₀

Annual

60

24-hourly

100

PM₂.₅

Annual

40

24-hourly

60

National Air Quality Monitoring Programme (NAMP)

Framework

The NAMP, established in 1984, forms the backbone of India’s air quality assessment framework. Monitoring is performed in partnership with:

  • State Pollution Control Boards (SPCBs)
  • Pollution Control Committees (PCCs)
  • The National Environmental Engineering Research Institute (NEERI)
  • CPCB Regional Directorates

By 2019, 804 stations were operational across 344 cities. PM₂.₅ was monitored at 317 sites in 147 cities.

Sampling Frequency

  • Gaseous pollutants: 4-hourly sampling over 24 hours.
  • Particulate matter: 8-hourly sampling over 24 hours.
  • Frequency: Twice weekly (104 samples annually)

Major Findings (2019)

  • SO₂: Concentrations remained well below the prescribed limits in most locations. Only 3 stations (in ecologically sensitive areas) exceeded the annual limit of 20 µg/m³.
  • NO₂: 91 locations (13%) in residential/industrial/rural areas exceeded the annual standard of 40 µg/m³.
  • PM₁₀: 577 locations (79%) exceeded the annual standard of 60 µg/m³, making it the most widespread pollutant.
  • PM₂.₅: 72 locations (37%) exceeded the annual standard of 40 µg/m³.

In cities, PM₁₀ and PM₂.₅ were the primary pollutants causing non-attainment, with 251 and 40 cities exceeding limits, respectively.

Data Analysis and Validation

All data collected under NAMP are entered in the Environmental Air Quality Data Entry System (EAQDES) managed by CPCB. CPCB performs the following to maintain data integrity:

  • Validation and cross-verification of field and lab results.
  • Identification of outliers and data gaps.
  • Regular review meetings with state agencies.

Training programs for technicians to ensure standard procedures.

Quality Assurance and Control

To ensure data reliability, CPCB:

  • Conducts station inspections through Regional Directorates.
  • Organizes training programs on data entry and instrument handling.
  • Reviews and updates Standard Operating Procedures (SOPs).

Promotes inter-laboratory comparisons for consistency.

Air Quality Trends

Between 2001 and 2019:

  • SO₂ levels showed a steady decline due to improved fuel quality and industrial emission controls.
  • NO₂ remained stable with a slight reduction despite increased vehicular numbers.
  • PM₁₀ levels fluctuated but remained above NAAQS limits in most urban centers.
  • PM₂.₅ showed stabilization and slight improvement in some regions.

Applicability and Policy Relevance

The findings from ambient air quality monitoring are directly used for:

  • Identifying non-attainment cities for targeted action under the National Clean Air Programme (NCAP).
  • Evaluating industrial and vehicular emission control strategies.
  • Supporting Environmental Impact Assessment (EIA) and urban air management plans.
  • Informing public health advisories and air quality index (AQI) reporting.

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