New Delhi, April 1 (India Science Wire): During May 2018, the national capital region and parts of North India were lashed by three strong dust storms in quick succession. In addition to widespread damage they caused to property and human life, these storms effected changes in air quality and atmospheric chemistry which may be harmful for human health, a new study has reported.
The
dust storms led to significant changes in the wind speed, temperature, and patterns
of vertical transport of atmospheric parameters, altering concentration of some
greenhouse and trace gases that are detrimental to air quality, the study
has found. Two of the three dust storms during May last year were hazardous and
killed over 100 people while injuring
several hundred more. Dozens of flights were either cancelled or
diverted.
Most
dust storms over the Indo-Gangetic plains originate in the Arabian Peninsula and
Thar desert areas and are known to contain nitrates that get converted into
oxides of nitrogen through a process called re-noxification.
“An increase in ozone precursors – carbon monoxide and nitrogen oxide – takes place after major dust events, which is likely to enhance surface ozone. Such processes also increase PM2.5 and PM10 and harmful greenhouse gases at the surface that has an adverse impact on human health,” researchers have concluded.
The
link between increase in surface ozone and dust is important and has been observed
during other dust events as well. For Delhi, the study said, the increase in
surface ozone is particularly strong, while it was far less in Kanpur, indicating
the gradual migration of dust storms further inward.
The
findings are based on observations from ground stations, satellite data, radio-sounding
data from balloon networks, besides global climate models. The ground data came
from AERONET network of NASA which has stations in Delhi, Kanpur, Ballia,
Jaipur as well as Karachi and Lahore. Data about pollution levels was sourced
from stations of the Central Pollution Control Board and also from the American
embassy in New Delhi.
In
addition to changes at ground level, there was a distinct shift in aerosol
loadings, size distributions, temperature and humidity patterns from surface to
lower troposphere. “Such shifts are accompanied by changes in distribution of
major trace and greenhouse gases all of which can lead to perturbations in
radiation balance, impacting the lower and middle troposphere regions,” the
study said.
“The
dust storms have both short and long-term impacts and some of the short-term
impacts can have very real consequences for human health. Mainly, the damage to
air quality is seen to come from an increase in aerosol concentration,
increases in respirable suspended particulate matter like PM 10, PM 2.5 and
also temporary fluctuations in tropospheric greenhouse gases like carbon
monoxide and ozone,” explained Dr Sudipta Sarkar, a scientist at the NASA
Goddard Space Flight Center and a member of the research team, while speaking
to India Science Wire.
“Ozone
is especially important as the interplay between surface ozone and dust events
has not been fully documented before and in that respect, we show that there is
definitely some inter-relationships and you would expect some level of surface ozone
increase and consequent health impacts,” he added.
According
to Dr Ramesh P Singh, visiting faculty at IIT Mandi from Chapman University and
another member of the team, “a better understanding of the impact of dust
storms could lead to formulation of warning and prediction strategies as poor
air quality impacts millions of people. There is an urgent need for
comprehensive monitoring or early warning systems, given the high frequency of
dust storms in the pre-monsoon season in the northern and north-western parts
of India.”
“The
extreme heating of land to the north and west of India creates additional winds
into India which fuel both widespread floods during the monsoon and dust storms
during pre-monsoon months. These systems can be predicted as they trek into
India so early warning systems can definitely be developed. It also means that
mitigation effects in terms of greening and land use change may not be sufficient
as remote source regions continue to warm,” explained Dr Raghu Murtugudde, professor of atmospheric and oceanic science at the
University of Maryland and visiting professor at IIT Bombay. He was not associated
with this study.
The
study team included Sudipta Sarkar (NASA Goddard Space Flight Center),
Ramesh P Singh (Chapman University), Akshansha Chauhan and Rajesh Kumar
(Chapman University, Greater Noida). The study results have been published in
journal GeoHealth.
By Dinesh C Sharma
