Why dust storms are a growing threat

It’s approaching peak summer, and dust hangs in the air. For 15-year-old Shreyas, diagnosed with asthma six years back, summer once offered a respite from air pollution. But that was until a couple of years ago. Now, even the hot weather brings with it increased likelihood of asthma attacks, allergies and similar symptoms.
Shreyas’s doctor blames rising pollution levels triggered by ever-intense dust storms, blowing in either from the Arabian Peninsula or the Thar desert.And the specialists agree.
Delhi-NCR is no stranger to dust storms during May and June. For decades, the region has been witness to these squalls, in which sand particles from the Thar, at their driest before the monsoon, are carried along on strong winds towards the capital and its surrounding areas. But, very rarely did sandstorms lead to a jump in air pollution. Now, for those sensitive to even the slightest worsening in air quality, the heat of India’s north brings with it as much misery as the cold.

A recent study attempted to quantify the impact of the dust storms of May 2018, unprecedented in their ferocity, on the quality of air over Delhi. The study revealed that various pollutants, including deadly ozone, rose during last year’s extreme event, imperiling the health of residents.
"Dust originating from Sahara and Thar desert areas are known to be rich in nitrates that convert as oxides of nitrogen. Hence, an increase in ozone precursors (carbon monoxide and oxides of nitrogen) takes place after major dust events in Indo-Gangetic Plain that is likely to enhance surface ozone," states the study, titled ‘Impact of Deadly Dust Storms (May 2018) on Air Quality, Meteorological, and Atmospheric Parameters Over the Northern Parts of India’. It continues, "Such processes also increase PM2.5/PM10 and harmful greenhouse gases (ozone and carbon monoxide) at the surface that has an adverse impact on human health."
Using data from space platforms, ground stations and global climate models, the study scrutinised details gathered during three back-to-back dust storms that swept the north a year back. It found that during the storms, Delhi experienced the worst air quality relative to other cities, with both PM2.5 and PM10 concentrations surging notably during the second and third dust storms (behind the research was senior author Ramesh P Singh, professor at Chapman University, California, US; lead author Sudipta Sarkar, chief research scientist at Goddard Space Flight Center, NASA; and co-authors Akanksha Chauhan and Rajesh Kumar, Sharda University, Greater Noida).

Another study, carried out in Delhi-NCR by the Centre for Science and Environment (CSE) last summer, also discovered an increase in ozone levels during the onset of summer. It found that Gurugram faced the highest number of days (in Delhi-NCR) on which ozone levels exceeded the eight-hour standard, during April and May 2018.
"On 57% of days during this period (in Gurugram), ozone has recorded levels higher than the standards; during May alone, 71% of the days have recorded exceedance. In Faridabad, 34% of days, and in Noida 26% of days have recorded exceedance," the study noted. The CSE research relied on data from 31 automatic monitoring stations of the Delhi Pollution Control Committee, Central Pollution Control Board and India Meteorological Department.
Worryingly, high levels of ozone are associated with premature death counts, putting the lives of those with respiratory diseases, particularly children and the elderly, at serious risk. Add increased concentration of nitrogen oxide and particulate matter, and you have a toxic summer concoction.
Kushagra Rajendra, head of department, Amity School of Earth and Environmental Sciences, says two factors explain why the summer air over Delhi-NCR has become fouler. "First, as the indigenous sources of pollution are already high in the region, dust-laden winds lead to deterioration in the air quality," he told TOI.
"For example, if a glass is already 95% full, even the slightest addition would lead to spillage — same is the case with air pollution in Delhi-NCR. Second, natural barriers, including green spaces and the Aravalis, have been degraded over the years," Rajendra added.

So, where before only winters would trigger respiratory ailments and allergies, today there’s no guarantee that summer wouldn’t bring the same. Because air pollution, says senior pulmonologist Dr Himanshu Garg, has become a year-long eventuality.
"While earlier we were witnessing five to 10 patients a week with respiratory illnesses and allergies during this season, now the number has gone up to 20-25 cases," said Dr Garg. Cases of asthma among the elderly, he adds, have seen a spike during this time of year. "Generally, people manifest asthma episodes by the age of 30. However, manifestations of asthma are now being reported in elderly — environmental factors are clearly responsible for this trend."
There’s more evidence that our health is adversely impacted by the pollution that is generated by dust storms, says Dr Arunesh Kumar, senior pulmonologist at Paras Hospital, Gurugram. "Though sand particles are not very fine, they can trigger symptoms of asthma and various other allergies and respiratory ailments," he pointed out.
It’s a vicious cycle. "The problem is that the underlining pollution levels remain high throughout the year in the city," holds Dr Garg. "While stubble burning and low wind speed lead to a rise in concentration of pollutants during winter, dust storms play spoilsport during summer," he informed.

Clearly, there is an immediate need to preserve natural barriers to dust storms. More importantly, say the experts, authorities must dump expediency in favour of durable solutions, to bring down local sources of pollution.
Ramesh P Singh, senior author of the study, and professor at Chapman University, California, US, says we can’t prevent dust storms. "However, we can deal with the situation by providing an early-warning system and a website where people can visualise or monitor dust. The early-warning system will also help in working on bringing down other sources of air pollution so that dust storms don’t lead to a rise in air pollution," he adds.
"At one time, the thick forests of the Aravalis would give rise to seasonal rivers, which helped moderate wind speed and acted as a barrier in countering strong dust-laden winds," explains C R Babu, professor emeritus and head of the Centre for Environmental Management of Degraded Ecosystem (CEMDE) at Delhi University.
"The Aravali range acted as a constraint and checked the spread of the Indian desert towards upper Indo-Gangetic plains — its degradation is a major cause of dust storms. Moreover, vegetation covers within the city have also gone down, making the situation worse," he reminds.
Alas, the Aravali range is no longer the robust buffer it once was, against extremes of weather. For this state of affairs, unchecked mining, widespread land-use change and rampant exploitation of the terrain is to blame. All the more reason, insists Rajendra, to revive this ecosystem. "Authorities should work on long-term plans to keep indigenous sources of pollution, including diesel and vehicular pollution, unregulated waste dumping and construction activities, under control throughout the year," he advises.
It might, however, be too late for those who have prioritised their physical and emotional wellbeing over the prospect of a well-paid job. And unless the authorities show more urgency to tackle what is quickly becoming an emergency situation, many more might consider leaving the dust bowl that is now Gurugram.