It's time to wake up to 'Himalayan' threat of aerosols

It’s time to wake up to ‘Himalayan’ threat of aerosols
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It’s time to wake up to ‘Himalayan’ threat of aerosols

Highlights

Mineral dust, biomass burning, secondary sulphate, secondary nitrate from northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area, and long-range transported marine mixed aerosols are the main sources of aerosols (extremely small solid particles, or very small liquid droplets, suspended in the atmosphere) in the central Himalayan region, shows a study

Mineral dust, biomass burning, secondary sulphate, secondary nitrate from northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area, and long-range transported marine mixed aerosols are the main sources of aerosols (extremely small solid particles, or very small liquid droplets, suspended in the atmosphere) in the central Himalayan region, shows a study.

This dust transport and forest fires are the main sources of total suspended particles (TSP), particularly in the pre-monsoon period (March-May) when the TSP concentration peaks in the region. The study on the atmospheric chemistry, emission source origins and transport pathways of aerosol over the central Himalayan region will help assessment of contributions and temporal variability of sources that influence the area through regional transport as well as climate impact assessments.

With a unique role in the Asian climate, the Himalayan region is considered a vulnerable environment. Several chemical speciation studies have been performed for carbonaceous aerosols and inorganic species over the western and the central Himalayas in the last decade, reporting the dominance of transported aerosol plumes from the Indo-Gangetic Plains.

However, there is a knowledge gap regarding the primary and the secondary organic carbon (POC, SOC) fractions, along with a lack of statistical methods for identifying and quantifying the sources of air pollutants at a receptor location (receptor model) in the central Indian Himalaya.

In order to address this, researchers at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, an autonomous research institute under the Department of Science and Technology (DST), along with Indian and foreign collaborators, studied the chemical composition and source apportionment of TSP ( which includes all the aerosols and air pollution) in the central Himalayan region. The main source regions for aerosols at this remote background location (Nainital) were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area.

The research revealed that the main aerosol sources (factors) in Nainital were mineral dust (34%), biomass burning (27%), secondary sulphate (20%), secondary nitrate (9%), and long-range transported marine mixed aerosols (10%), exhibiting distinct seasonal patterns.

There was predominance of mineral dust in spring and summer and biomass burning and secondary sulphate in winter. The transported marine mixed aerosol source was mainly associated with SW monsoon air masses during the summer season. The results of the study published in the journal of 'Atmosphere' show that Carbonaceous aerosols (Organic Carbon (OC) and Elemental Carbon (EC) were the maximum in winter due to the intensification of biomass burning over the Indo Gangetic Plains and the Himalayas because of domestic heating and shallower mixing layer.

The researchers also suggested a significant effect of biomass-burning aerosols, while the relatively high water-soluble organic carbon and significant contributions of biomass burning, secondary, or aged organic aerosols over Nainital.

As per WHO (2016) estimates, 10 out of the 20 most populated cities in the world are in India. Based on the concentrations of PM2.5 emissions, India was ranked the fifth most polluted country by WHO (2019), in which 21 among the top 30 polluted cities were in India. The Indian cities, on average, exceeded the WHO threshold by an alarming 500%.

The continuous degradation of ambient air quality in the urban centres of India demands effective measures to curb air pollution. Though various policy measures are being introduced by the government to reduce vehicular and industrial emissions, the extent to which these measures are implemented is questionable.

The lack of infrastructural facilities, inadequacy of financial resources to implement advanced infrastructural innovations, difficulty in relocation of the industries from the urban centres even after mandatory court decisions, and above all, the behavioural patterns among people in accepting the green solutions are some of the crucial impediments on the road to environmental protection that our country seems to be struggling to overcome today.

Studies published by The Energy Resources Institute (TERI), particularly the work of Dr Bhola Ram Gurjar, Professor of Civil (Environmental) Engineering and Dean of Resources & Alumni Affairs (DORA), Indian Institute of Technology, Roorkee, highlight not only the lacunae in the policies but also chalk out ways and means of tackling the menace.

Dr Gurjar decries the lack of transparency in the research studies we undertake to seek solutions to such a problem. Air quality management in megacities is a four-stage process that involves problem identification, formulation of policies, their implementation, and control strategies.

As the professor avers, air quality modelling, emission inventories, monitoring the concentration of pollutants, and source apportionment studies and related methodologies involve a complex analysis of extensive data sets for the effective management of air quality standards.

Due to the lack of transparency and unavailability of data, uncertainties are introduced in the estimation of atmospheric concentrations. Minimising these uncertainties with our scientific understanding is one of the major challenges towards addressing the issues related to air quality.

There is little that we can do to ward off polluted air from our neighbours. We cannot even think of joint efforts to tackle the menace as the political chasm that divides us is vast. We can only look at what we can do and decide. The Air Pollution Control Association is categorical in stating that the air pollution control process begins with a set of determinations which define the level of air quality desired in any community. These determinations involve questions of fact and value; they involve a partnership between science and philosophy, and between administration and politics. "They involve questions of health, of esthetics, of economics, of engineering, and of law. There is no magic formula, no automatic process, no simple mechanical step which results in a proper determination of the kind of air quality a community should enjoy. Within our society, within the context of our system of government, the final responsibility and authority for these kinds of judgments and determinations is vested in the legislative branches of our institutions of government."

As is known to everybody, these judgments are not made in a vacuum. They are a product of demand and desire; they reflect the values held by the community. This process of defining community values, problems, and needs is extremely complex. Community needs, like personal needs, often are not recognized by those concerned until they have arrived at the crisis stage.

When do we wake up?

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