Monday, December 24, 2007

Haze over North India

Thick blanket of Haze spreads over North India.

Dr. Nitish Priyadarshi

Haze lingered in Northern India south of the Himalayas, for several days in December 2007. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua Satellite captured this image on December 16, 2007. In this image, the haze appears as a dull gray blur. The haze extends southward, thickening somewhat in the south west. North of the Himalaya, clouds clutter the otherwise clear skies.
The NASA image was created by Jesse Allen, using the data obtained from the Goddard Land Processes data archives (LAADS).

Haze often occurs when dust and smoke particles accumulate in relatively dry air. Regional haze pollution, mainly in the form of sulfate, organic and nitrate fine particles, results in poor visibility. Haze is composed of very small fine particles, smaller than 2.5 micrometers (µm) (over 20 times smaller in diameter than human hair) that are suspended in the air. These particles originate from a variety of sources, some natural, but much of it originates from power plant and automobile emissions. Haze is generally composed from five major components: sulfate aerosol, nitrate aerosol, organic carbon aerosol, elemental carbon, and dust from the earth’s crust and also from forest fire as it was in Indonesia in 1997. In 1997, the dry season lasted longer than usual. There was no rain to stop the slash-and-burn fires that farmers set and they burned out of control. The haze spread to the neighboring countries of Singapore and Malaysia. The thick blanket of smoke drastically reduced visibility in the Malacca Strait between Sumatra and Peninsular Malaysia. The haze triggered asthma attacks, severe coughing, breathing difficulties and eye and skin irritations.
Haze pollution is that portion of haze that comes from man-made sources. The largest source of regional haze pollution in India is from coal-fired power plants emitting sulfur dioxide and nitrogen oxide that then reacts in the atmosphere to form fine particles and automobiles. The other sources responsible for Haze Pollution are the chemical industries, metallurgical plants and smelters, petroleum refineries, mining etc.
Recent scientific studies have illuminated the associated human health impacts of exposure to fine particles, such as respiratory and cardiac disease and premature death.
Few years ago high levels of carbon monoxide (red and yellow pixels) was observed over the Indian sub-continent during March by the NASA. These values are associated with industrial activity in the region just south of the Himalayan Mountains. Notice that to the north, the Himalayas are characterized by low values (blue pixels).

Dr. Nitish Priyadarshi
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