As we know microbes are everywhere in our environment and environment includes all the things that is present in our day to day life, Micro-organisms are present in water, air, on the surfaces, as well as they can be seen in very hot and cold temperature. Micro-organisms are so tiny which we cannot see with naked eyes, microbes are measure in micron. Viruses play important role in microbial ecology and some infectious diseases, but relatively little is known about the concentrations, sources, transformation, and fate of viruses in the atmosphere.
We have measured total airborne concentrations of viruses like bacterium- like particles (VLPS between 0.02 and 0.5µm in size and BLPS between 0.5and 5µm) in indoor air quality.
Microbial level in air involves hundreds of species of bacteria and fungi that grow indoors when sufficient moisture is available. The air we breathe is containing more than 1,800 kinds of bacteria, including relatives of microbes. Bacteria that can be identified in indoor air are micrococci, staphylococci, and cornybacteria.
Polluted air has significant threat to human health. Exposure to particulate matter (PM) harmful gases contributes to cardiovascular and respiratory diseases, including allergies and obstructive lung diseases. Air quality is commonly described by the concentration of PM (ranging in diameter from 10µm or smaller (PM 10) to below 0.1µm (PM 0.1).
Indoor air pollution refers to the accumulation and diffusion of various chemical, biological , and physical pollutants, resulting in decline in indoor air quality and risk to daily life activities, work and health. Bioaerosols accounts for 5-34% of indoor air pollution and mainly include bacteria, fungi, viruses and spores.
For example, people who live and work indoors long term might show many symptoms, such as headache, nausea, dizziness and inattention; this condition is called as sick building syndrome.
Methods used in control microbial level in air
Filtration
A method widely used today is the filtration of air in HVAC systems. Filtration is an effective way to keep microorganisms from entering the building envelope by mechanical ventilation. About 80 to 90% filters can produce air quality improvements that approach those achieved with HEPA filters (HEPA filters remove 99.97% of all particles 0.3 μm or larger in diameter).
Ultraviolet radiation
Low-pressure mercury vapors arc lamps emit UV light with a wavelength of 253.7 nm. UV light damages the DNA/ RNA of microorganisms and makes them harmless. UV light inactivates pathogen by forming pyrimidine’s (Cytosine, Thymine, and Uracil), which can interfere with transcription and replication. UV radiation is primarily a function of two factors: the intensity of the UVGI energy and the duration of exposure
Photocatalytic oxidation
Photocatalytic oxidation (PCO) is a very effective air purification method that can destroy particles as small as 0.001 microns (nanometer), whereas HEPA filters can only filter particles smaller than 0.3 microns. Photocatalytic oxidation destroys microbes, volatile organic compounds (VOCs), and chemically active compounds (CACs).
Plasmacluster ions
Plasma cluster suppresses airborne virus and bacteria, airborne and proliferating mould, unpleasant odour and allergens such as dust mites and faeces. PCI, or plasma cluster ions technology, claims to be able to neutralize 26 different types of dangerous airborne chemicals. The ion generator splits airborne water molecules into positively charged hydrogen (H+) and negatively charged oxygen (O2) using an alternating plasma discharge (between two electrically charged plates: anode and cathode).
Air pollutant can also be treated through biological means, commonly referred as bioremediation. It is the use of organisms to degrade or transfer hazardous substances into less toxic or nontoxic ones.
Mechanism of bioremediation
The mechanism or the procedure of bioremediation is based on the activity of microorganism we use. Those living organisms degrade and take the organic compounds such as carbon, electrons, source of cell building materials, energy source for their growth and reproduction.
1: Analysis of contaminants and choosing microbes.
2: The microbes are examined, cultured, and placed in the polluted environment.
3: These microbes consume all the contaminants as organic nutrients and grow enormously.
4: Then they convert those nutrients into carbon dioxide and water removal of contaminants occurs.
