Tuesday, October 23, 2007


Indoor or outdoor air may contain thousands or even millions of microorganisms and biological particles in just one cubic meter of air. These airborne particles are collectively referred to as bioaerosols. Examples of bioaerosols include viruses, bacteria, fungi, pollen, fragmented particles from microbial cells or insects, and by-products of living organisms (e.g. animal dander, insect excrement). The size of these particles generally varies between a fraction of a micrometer (µm) to approximately 30 µm. Bioaerosols may originate from numerous natural or man-made sources such as agriculture (harvesting, storage, composting etc) and industrial activities (manufacturing, food processing etc), indoor surfaces (ceiling, wall, carpets, house plants) and water treatment plants etc.
Particle size is an important factor in determining risks associated with microbial contamination. In general, particles > 20 µm (fungi, algae, pollen etc) affect Region 1, Particles < 20 µm (mostly bacteria and some fungi, algae) affect Region 2 and particles < 1or 2 µm (mostly viruses and some bacteria) affect Region 3.

Modern airborne sampling of bioaerosols employs one of three protocols: 1) impactor sampling, 2) liquid impinger sampling, or 3) filtration sampling. Each of these methods pulls a measured volume of air with the aid of an electric or battery-powered pump. The air is then directed through a chamber (or a series of chambers), guiding the spores (particles) on a specific trajectory to a solid agar disc or adhesive medium (impactor samplers), a liquid buffer (impinger samplers), or a filter (filtration samplers). With the impactor method, cells or spores are usually cultured on a suitable nutrient medium. Each organism is then identified and reported as colony forming units m-3 (CFUs per cubic meter).
Since state and federal standards for most of the bioaerosols do not exist, the most common practice compares indoor cell concentrations to concentrations measured outdoors during the same sampling event. This unofficial benchmark implies that indoor counts should not be significantly greater than outdoor counts. When indoor concentrations are significantly greater, it is generally assumed that an indoor amplification source exists. In other words, there is likely microbial contamination present on indoor building materials. Such basic approaches do not apply to all microorganisms. Relatively high levels of one airborne microbe may represent very low risks, while extremely low levels of more dangerous contaminants should trigger immediate action. Other important factors must also be considered, including the location of air samples, frequency of detection, frequency of sampling, type of air sampler, and the environmental conditions while assessing the effects of bioaerosols.
For more information and understanding, please refer the following book and other literature

Macher, Janet (Ed.), Bioaerosols: Assessment and Control, American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 1999.
ISBN: 978-1-882417-29-2

Monday, October 15, 2007

Conference & Symposiums on Environment Science: AGU and AMS 2007-2008

Annual fall meeting of American Geophysical Union (AGU) and annual meeting of American Meteorological Society (AMS) is approaching close in December 2007 and January 2008 respectively. These are two biggest events in USA where more than 20 thousands scientist from around the world get together to discuss, show and present their research in various areas of Earth Sciences. Environment science is one of the main focus area in both meetings and several thousands research studies on the same will be presented.

The next AMS (88th Annual Meeting) will be held in, New Orleans, LA, USA during 20-24 January 2008.

Please click on the link to see various topics covered by AMS-2008



This year AGU Fall meeting will be held in San Francisco, CA, USA during 10–14 December 2007.

For more details click here


Friday, October 12, 2007

IPCC gets Nobel Peace Prize

The Norwegian Nobel Committee has decided that the Nobel Peace Prize for 2007 is to be shared, in two equal parts, between the Intergovernmental Panel on Climate Change (IPCC) and Albert Arnold (Al) Gore Jr. for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change.

Indications of changes in the earth’s future climate must be treated with the utmost seriousness, and with the precautionary principle uppermost in our minds. Extensive climate changes may alter and threaten the living conditions of much of mankind. They may induce large-scale migration and lead to greater competition for the earth’s resources. Such changes will place particularly heavy burdens on the world’s most vulnerable countries. There may be increased danger of violent conflicts and wars, within and between states.

Through the scientific reports it has issued over the past two decades, the IPCC has created an ever-broader informed consensus about the connection between human activities and global warming. Thousands of scientists and officials from over one hundred countries have collaborated to achieve greater certainty as to the scale of the warming. Whereas in the 1980s global warming seemed to be merely an interesting hypothesis, the 1990s produced firmer evidence in its support. In the last few years, the connections have become even clearer and the consequences still more apparent.

Al Gore has for a long time been one of the world’s leading environmentalist politicians. He became aware at an early stage of the climatic challenges the world is facing. His strong commitment, reflected in political activity, lectures, films and books, has strengthened the struggle against climate change. He is probably the single individual who has done most to create greater worldwide understanding of the measures that need to be adopted.

By awarding the Nobel Peace Prize for 2007 to the IPCC and Al Gore, the Nobel Committee is seeking to contribute to a sharper focus on the processes and decisions that appear to be necessary to protect the world’s future climate, and thereby to reduce the threat to the security of mankind. Action is necessary now, before climate change moves beyond man’s control.