An Integrated Study of Air Pollutant Sources in the Delhi National Capital Region (NCR)

Lead Research Organisation: University of Surrey
Department Name: Civil and Environmental Engineering


Delhi was rated the most polluted city in the world for ambient air pollution by the WHO in 2014. Some 46 million people live in and around Delhi - 18m in the city, and the remainder in the surrounding National Capital Region (NCR). Annual mean levels of particulate matter (PM), the most important air pollutant for health in Delhi, exceeded WHO guidelines by a factor of 15 during 2014, and are responsible for very substantial chronic and acute health impacts, with attendant economic costs. Development of effective strategies for improvement in air quality requires quantitative understanding of the sources, formation processes, regional budgets and chemical and physical nature of airborne particulate matter; however, such knowledge is not yet available.

ASAP-Delhi addresses this requirement: The project will provide a quantitative assessment of the sources, characteristics, abundance and formation processes for PM in Delhi and the surrounding NCR. The project is designed to address key science questions (below), with a philosophy of obtaining insights into pollutant sources and budgets from high quality direct observation - i.e. based upon measurement of the species actually present in the air at ground level within Delhi, without dependence upon other data. The project represents a focussed collaboration between leading researchers from the UK (Birmingham, Surrey) and India (IITD, NPL), who have a track record of successful joint collaboration and publications from previous funded air quality projects in Delhi.

ASAP-Delhi will (i) perform the most detailed physical and chemical characterisation of PM present in Delhi, and in the surrounding National Capital Region (NCR) to date; (ii) produce source profiles (chemical signatures) for the principal PM sources in Delhi; (iii) identify and quantify the contributions of different sources to the PM burden in Delhi (and the NCR) - for both PM mass concentration and particle number [with differing implications for health], by application of multiple, independent, established and novel receptor modelling approaches, such as chemical mass balance, radiocarbon, and number size distribution based source apportionment; (iv) estimate the impact of NCR emissions upon air quality in Delhi (key to effective regional air quality policy) and (v) evaluate a series of new hypotheses for the formation of PM during pollution episodes, essential for accurate model predictions of future PM levels.

We will address these objectives through a series of field observations, combining online measurements with state-of-the-science offline analyses, in Delhi (urban background locations - year round sampling combined with two "intensives"), the surrounding NCR (seasonal measurements at five sites) and a rural background location (150 km upwind). Our measurement strategy combines (i) established methodologies - to deliver a high quality, systematic, coherent measurement dataset, with a novel spatial distribution - and (ii) new state-of-the-science tools and analytical approaches. This provides a balance between international quality observations (in support of ASAP-Delhi and other programme components) and novel metrics, whilst also recognising the realities of fieldwork in such environments. ASAP-Delhi will draw upon results of other projects in the APHH India programme, and will provide the key observational insights in support of air quality model development, evaluation of human health impacts, and development of mitigation policies in the wider programme.

In addressing public health, policy and development issues, and providing a platform to enhance air pollution research in India, ASAP-Delhi addresses the ODA support categories of (i) people and (ii) research programmes, in addition to providing a step-change in understanding of the sources of PM in Delhi (the key insight required by policymakers).

Planned Impact

The key impact from ASAP-Delhi will be to deliver a step-change in understanding of the sources and processes forming of air pollutants in Delhi, providing science insight for policymakers to use in developing air pollution control measures. In conjunction with other projects within the Indian Megacity programme, this will lead to improved health and wellbeing for millions of people in Delhi - the ultimate beneficiaries.

We have identified three tiers of non-academic beneficiaries from the project, alongside the scientific / research community:

Tier 1: Stakeholders who will be direct beneficiaries of this project, with sustained engagement, e.g. the DPCC (Delhi Pollution Control Committee).

Tier 2: Wider stakeholders who have clear interests in the outcome of this project and the wider programme, and who may be directly engaged in the work, e.g. governmental departments such as the Central Road Research Institute (CRRI) and CPCB (Central Pollution Control Board).

Tier 3: Stakeholders who have a broader interest in the findings of the overall programme; for example, the media, WHO, the World Bank, private sector businesses in directly affected areas, and the general public.

Research Community: The project findings will be of direct relevance to researchers working in on air pollution issues - sources, processes and impacts - in Delhi and related environments.

They will benefit in the following ways:

Tier 1: The PM source apportionment results are essential for developing air pollution control strategies and will therefore provide direct insight for policy makers including the DPCC. In addition, the source apportionment and air pollutant process understanding will also indirectly benefit policy makers by constraining and improving predictive air quality models, which are the basis for developing long-term and short-term air pollution control strategies.

Tier 2: Air pollution control requires actions from other governmental departments such as those responsible for transportation. The results from ASAP-Delhi will provide direct assessment of the relative importance of different sectors to air pollution loading in Delhi and surrounding areas. This will help these stakeholders to identify potential policy actions to control air pollution in the most effective manner.

Tier 3: Delhi is the most polluted city in the world for ambient air quality (WHO, 2014). Thus, it serves as a natural laboratory to study air pollution on human health. Our results will benefit health effect studies within the programme by providing detailed physical and chemical characteristics of PM in Delhi. This will be of interest to Tier 3 stakeholders such as WHO which is keen to more accurately and precisely quantify air pollution impacts on human health. Environmental agencies elsewhere will benefit from this work via the overall programme in providing improved understanding of air pollution impacts on human health.

Ultimate beneficiaries - the general population of Delhi will benefit eventually from the contributions of ASAP-Delhi, and the overall programme, to identification of optimal air quality control strategies, leading to improved well being and health.

Steps to maximise impact with these beneficiaries are outlined in the ASAP-Delhi Pathways to Impact document, which will be delivered collaboratively with other projects in the overall APHH-India Programme.


10 25 50
publication icon
Kumar P (2017) The influence of odd-even car trial on fine and coarse particles in Delhi. in Environmental pollution (Barking, Essex : 1987)

publication icon
Sharma AK (2018) Air pollution and public health: the challenges for Delhi, India. in Reviews on environmental health