Heavy smoke and haze over northern India 

Today’s Image of the Day from NASA Earth Observatory features heavy smoke and haze over northern India on November 20, 2023.

“The poor air quality is a seasonal occurrence – the product of smoke from crop fires mixing with urban pollution from traffic and industry, emissions from cooking and heating fires, windblown dust, and a range of other sources,” explained NASA.

“The timing is also important: all this particle pollution enters the atmosphere when seasonal weather patterns tend to trap air pollution near the ground.”

On the day this image was captured, air quality monitors recorded unhealthy to hazardous levels of airborne particulate matter.

“The World Health Organization considers 15 micrograms per cubic meter of fine particulate matter (PM2.5) to be a safe limit. But ground-based air quality monitors routinely measured levels that exceeded 300 and, at times, 500 micrograms per cubic meter in November,” said NASA.

“As air quality deteriorated, doctors urged people to limit outdoor activity and reported increases in respiratory problems. The haze also led to pauses in construction, restrictions on vehicle use, and school closures.”

Hiren Jethva, a Morgan State University researcher based at NASA’s Goddard Space Flight Center, uses satellite images to track fire activity in northern India each fall. 

“In terms of satellite-detected fire counts, the fires in Punjab and Haryana have been less severe this year – about 40 percent less than the five-year average detected by Aqua’s MODIS – but they’re still numerous enough to cause poor air quality in Delhi,” said Jethva. 

The results of one particular analysis suggest that crop fires were responsible for about 20 percent of the fine particulate pollution detected in Dehli in early November. 

Ritesh Gautam, previously an atmospheric scientist at NASA, has been studying long-term trends in fire activity, haze, and atmospheric stability in the region. His team found that an increasing numbers of fires since the early 2000s have coincided with a 90 percent increase in the amount of aerosol-laden haze.

“It’s a double whammy. It’s not just the smoke itself, but likely the way that the increasing smoke is changing the meteorology that makes this such an intense problem,” said Gautam. 

“On the other hand, our results suggest that reducing late autumn burning and other anthropogenic emissions during the winter might have an even greater effect in reducing the haze than previously thought.”

The image was captured by the Moderate Resolution Imaging Spectroradiometer on NASA’s Aqua satellite.

Image Credit: NASA Earth Observatory 

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