Frequently Asked Questions: (8) Local vs Global Pollution Nexus

While health effects drive most of the PM pollution concern, PM also affects regional and global atmospheric chemistry and the radiation balance. Aerosol particles scatter and absorb solar radiation, and also alter the formation of cloud droplets. These physical interactions change the earth’s radiation balance, affecting local and global temperatures and possibly precipitation.

The Aerosols (PM) and ozone that are usually considered only in the air quality domain, also affect climate change. The understanding of the impact of aerosols on the climate system and how to evaluate this impact for policy relevant issues is very low. Research continues to assess the effects of many different types of aerosols on climate under different conditions.

Also see a review - Black Carbon to the Rescue.

PM pollution can also impact visibility in urban centers. Mountains or buildings once inplain sight can suddenly be blocked from view. Air pollution that reduces visibility is often called haze or smog.

The term smog originally meant a mixture of smoke and fog in the air, but today it refers to any visible mixture of air pollution. The incidents of haze and smog in cities are increasing, which typically starts in cities and travels with the wind to appear in the more remote areas.

One consequence of smog over any given area is that it can change the area’s climate. Certain dark particles, such as carbon, absorb solar radiation and scatter sunlight, helping produce the characteristic haze that is filling the skies over the world’s megacities and reducing visibility.

See other FAQ's.

Beijing Announces Cleanest Month in 9 Years?

May 14th, 2009. Note:
Thanks to Vance for flagging the editorial mistake by China Daily. This is the "cleanest April" in 9 years.

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Blue Skies are Shining on Beijingers ! says China Daily

The city experienced 23 blue sky days in April, 2009 (a blue sky day = day with API less than 100).

Question: Why is this the cleanest month in 9 years,
August 2008, 30 days with average API of 56;
September, 2008, 29 days with average API of 56;
August 2006, 30 days with average API of 74;

and April 2009, 23 days with average API of 84?

See statistical Beijing Air Pollution Index (API) analysis @ Room with a View

Also see

• Air Quality Monitoring in Asia
• Air Quality Index in Urban Centers
• Environmental assessment of Beijing 2008 Olympic Games (UNEP)
• Dust Storms, Fires, and Haze Pollution in Asia
• Particulate Pollution in Asia
  
• Articles on air pollution and climate on "China Dialogue"
• More new cars are registered in 2009 in Beijing, China
  
• Transport Emissions Inventory for China
• Photo Diary of Air Pollution in Beijing
• Sensing air quality in Beijing (Interactive Maps)
• Beijing still hazy !!
• Air pollution in Beijing

Brown Cloud's of Pollution Over Asia (ABC)

aka Atmospheric Brown Cloud over Asia, is back in the news.

(1) Science Daily - Sources of climate and health effecting pollution over South Asia identified.
(2) TIME (CNN) - Study gets inside the world's "Brown Cloud".
(3) BBC - Asia's Brown Clouds 'warm planet'.
(4) Int. Herald Tribune - Haunting Asia, a brown cloud blots out sun.
(5) New York Times - Study pinpoints main source of Asia's Brown Cloud.
(6) Times of India - Wood fires fueling India's brown haze.
(7) Scientific American - Wood and dung fires feed Asia's brown cloud.
(8) Live Mint (WSJ) - Burning biomass contributes 70% of brown cloud soot.
(9) Scientific American - Clear the air down south.

Here is a list of interesting (and useful) publications, news, and journal articles on ABC in the past

• ABC Regional Assessment report (2008)
• Impacts of Asian megacity emissions on regional air quality during spring 2001 (JGR)
  
• NASA probes the sources of world's tiny particles
• Global and regional climate changes due to Black Carbon (Nature)
• INDOEX (The Indian Ocean Experiement, 1999) studies aerosols over the Indian Ocean
• Brown clouds over South Asia: Biomass or fossil fuel combustion? (Science)
• UNEP's Asian Brown Cloud experiment - see the impact assessment report (2002).
• Wikipedia
• New Directions: Atmospheric Brown Clouds (Atmospheric Environment)
• Aerosol radiative characteristics at Gosan, Korea, during the ABC East Asian Regional Experiment 2005 (JGR)
• Indian Ocean Experiment 1999: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze (JGR)
• How dangerous is the ABC?
• Brown clouds over South Asia: Biomass or fossil fuel combustion? (Science)
• Discovery of the ABC over the Indian Ocean, sets off flight
• ABC: Impacts on South Asian climate & hydrological cycles (PNAS)
• Air pollution & climate change, both reduce India's rice harvests (PNAS)
• North American, Asian, & Indian haze: Similar regional impacts on climate (GRL)
• Air pollution, greenhouse gases, and climate: Global & regional perspectives (Atmospheric Environment)
• Characterization of the seasonal cycle of south Asian aerosols: A regional-scale modeling analysis (JGR)
• Warming trends in Asia amplified by brown cloud solar absorption (Nature)
  
• Overview of the Atmospheric Brown Cloud East Asian Regional Experiment 2005 (JGR)