Himalayan smog along the Manali-Leh highway, diesel trucks to blame

Study finds high levels of sulphur from diesel emissions along the Manali-Leh highway, which winds 490-km through Tanglang La , one of the highest navigable mountain passes in the world . Sulphur dioxide causes asthma, breathing difficulty and acid rain.

There’s no getting away from air pollution, with new research finding high levels of smog from vehicular emissions along India’s high mountain highways.

Researchers from the University of Cincinnati (UC) in the US found sulphur pollution along the Manali-Leh highway, which winds 490-km through Tanglang La , one of the highest navigable mountain passes in the world at 17,480 feet.

“We measured incredibly high amounts of sulfur close to the highway. Some of those values are the highest ever reported in the literature and were likely connected to truck traffic,” said Brooke Crowley, an assistant professor of geology and anthropology, who did the study with UC graduate Rajarshi Dasgupta.

For the study, soil samples collected along the highway from a depth of 3, 9 and 15 cm were tested for hydrocarbons from wood and cow-dung emissions from cooking and heating, along with sulfur, total organic compound and 10 types of heavy metal.

The highest sulfur content was found at the base of the narrow ridges that are most prone to rockslides, where trucks wait for hours while the road is cleared of rubble.

Sulfur dioxide (SO2) is a major constituent of smog. Short-term expoure inflammes the respiratory system to make breathing difficult and trigger asthma attacks. So2, along with other sulfur oxides (SOx), react with other pollutants to form suspended particles that penetrate deep into the airways and lungs to cause asthma, chronic obstructive lung disease, heart attacks and strokes.

“At first glance, it’s easy to consider the region to be a pretty pristine place. But there are environmental impacts from humans,” said Crowley, who published the findings in the journal Archives of Environmental Contamination and Toxicology.

Last year, India ratified the Paris Agreement on climate change, which calls for participating countries to develop a plan to address temperature rise. India has a goal of meeting 40 per cent of its energy needs from renewable energy by 2030.

“There is no pristine environment left. You see black snow deposited on glaciers and snowfields in Tibet,” said professor Lewis Owen, head of the geology department, UC.”This study is adding to our data set about how we’re degrading the planet. Humans are the biggest geologic agents now. Some researchers are calling this geologic age ‘the Anthropocene’ after the human influence.”