Introduction

Origin of Aero-Biology probably dates back to 55 B.C when Lucretius, first observed the silvery dust particles dancing in a ray of sun-light. Since then, this important discipline of Biology and Environmental Science has progressed much. During this progress, various methods have been improvised and used for collection of air-born Bio-particules.

All such methods can be briefly summarized into four broad categories.

Gravity settling of air-born particles, either on a clean glass slide for direct observation, or on some nutrient medium, for culturing.

Impaction of air-born particles on an adhesive surface, either by moving collection surface against wind or by exposing such surface to wind currents.

Trapping particles by passing air through some liquid medium.

Filtration- Collection of particles from air current (mostly created by suction) by passing air through some filter medium (such as paper, cellulose or glass fibers etc).

Some of the air-samplers used so far, includes, Glass plates and Wind tunnel Salisburry, (1866), Rotarod Air-Sampler, Herrington et.al. (1959), Wind wane type Sampler- “Aeroscope” Lakhanpal and Nair (1958) , Tilak Sampler, Tilak and Kulkarni (1970), Verticle Cylinder ,Parshwanath and Ramalingam  (1979), Anderson Sampler, Cyclone Type Sampler, Burkard Spore Trap, Reuter Centrifugal Sampler, Casella Split Sampler, FAO Split Sampler and Sartorium Filter Sampler , Stationary and Mobile agarised plate and High volume Air Sampler- HVAS-9000C. Some of the more advanced, motorized and electronically equipped samplers are Active Count Sampler, Air-borne Particle Counters, Spin- air Sampler, Sartorium Air-port MDTS, Sampling by electrostatic charging of air-borne particles, High Volume air Sampler and Personal samplers.

Some of the material used as samples, include Sea-Dust Ehrenberg (1852), Rain Water, Karnik (1962), House Dust- Bernstain and Safferman, (1970), Building Walls and other sub aerial surface scrapings, Herrold Schlishting,(1975), Dust stormes , Folger et.al. (1967), Snow and Rain , Kawai (1984),Tree Leaves , Pal and Santra (1986)^, Foot Wear Dust, Food Dust, Leaf Dust, Bed Dust, Nasal Secretion and Spider Webs and Earthworm Castings ,Craigh et.al. (2002).

Material and Method

In spite of various types of samplers, in numerated above, there is always a need for a cheap, affordable, versatile sampler, at least for the purpose of preliminary qualitative observations.

Every household, commercial or institutional building has one or more ceiling fans.

Blades of these fans, while revolving, collect a thick coat of air-borne dust, especially on the edges of the fan blades. Thus a ceiling fan like a rotarod sampler collects by impaction, air-born particles on its blades. In this method instead of an adhesive coated strip, air particles collects directly on fan blade, due to electrostatic charge developed on the blade edges (due to friction with air). This initial dust layers, thus collected, absorbs moisture from air, which further enhances their ability of collecting more air particles. This process, finally results, in a thick sticky layer of fan dust. Further, these fans, mostly being out of normal human reach, collects dust, purely of aerial origin and are less prone to contamination. Considering all this, a preliminary study was conducted to find out possibility of using fans, as air samplers.

Before collecting samples, these fans were washed well with soap solution and finally with alcohol, to avoid all possible residue- contaminants. Fans were then allowed normal use for a period varying from 10 to 30 days. This being only a qualitative study, factors like fan blade size, fan speed, actual duration of use etc. were not taken into consideration. Each sample was collected in a sterilized test tube with the help of clean drawing brush.

Each sample, thus collected, was macerated with dilute Hydrochloric Acid (reaction carried out till all effervesces died out) to dissolve calcium and magnesium carbonates of dust. Remaining acid was washed well with sterilized distilled water, using a centrifuge, (to prevent bio-particles, flowing out). Remaining material, thus collected was mounted on a clean glass slide with glycerin, for further microscopic examination.

Samples were collected during a span of five months, i.e. January (late winter) to May (summer). They were collected from five varied localities at and around Nagpur. All samples were collected after necessary permission of concerned authorities. These sample sites were as follows-

Student’s canteen (semi intra mural sites) attached to a school (Baba-Nanak High School and Junior College) at Gangabai Ghat, a thickly populated commercial locality of Nagpur.

Bed-room (an intra-mural site) of a residential house at Bajaj Nagar, a residential locality of Nagpur.

Living room (intra-mural site) of a residential house at Pratap Nagar, a residential locality near city out-skirts.

Chemistry laboratory (an intra-mural site) of a college (S.K.Porwal Junior and Senior college for Science) at Kamptee, a small town about 30 Km. South-West of Nagpur and a semi-rural locality.

A school office (Bhalerao High School) at Saoner, a small agricultural village, 40Km. North-East of Nagpur, a rural locality.

Table 2-List of genera and species recorded

Results and Discussion

Out of fifteen samples, 517 algal fragments were recorded (Table 1). It is interesting to note that 2^nd sample at Kamptee locality, although collected only after 10 days, recorded enough number of algal particules, indicating towards, and the efficiency of this method.

As usual, Cyanophycean forms were predominant, followed by Chlorophyta, Bacillariophyta and Euglenophyta. A total of about 34 algal species, distributed over 24 genera were identified, indicating diversity of algal forms (Table-2).

Various Cyanophycean genera recorded were Phormidium, Oscillatoria, Chroococcus, Plectonema, Microcystis, Gloeotheca, Microcoleus, Spirulina, Gloeocapsa, Lyngbya, Scytonema, Merismopedia and Calothrix. Chlorophycean forms were Pandorina and Cosmarium. Bacillariophycean forms include Amphipora, Cymbella, Navicula, Nitzchia, Synedra, Pinnularia, Asterionella and Rhizosolenia. Euglenophycea was represented by Euglena only (Table-2).

These results were found to be consistent with previous such findings. Several algal forms observed here were also reported in many such findings from Nagpur, Kamat and Harenkhedkar (1976), and also from other parts of India, Santra S.C (1987).

More algal forms were recorded from rural samples than that of urban ones, similar to previous such reports, Sharma et.al; (2006).

From the above observations and discussion, it is evident that ceiling fans can be used as cheap versatile air-samplers, especially for qualitative investigation.

Acknowledgements

Author is thankful to Dr.M.Z.Patel, Shri. S.V.Khadake, Mr.Sahu, Dr. M.N.Ghoshal of Kamptee and Mr.Khedkar, of Saoner, for their help.

 References

1. Salisbury, J.H. (1866) On the cause of intermittent and remittent fevers investigations, which tend to prove that these affections are caused by certain species of Palmellae. Am. J.Med. Sci: 51: 51-57.
2. Harrington J.B, G.C.Gill and B.R.Warr (1959), High efficiency pollen sampler for use in clinical allergy. J.Allergy: 30: 357-375.
3. Lakhanpal and Nair, (1958) Survey of atmospheric pollen at Lucknow. J.Sci.Ind.Res. 17(5): 80-87.
4. Tilak S.T. and Kulkarni R.L. (1970) A new air sampler. Specialia, 443-444.
5. Parswanath H. V. and A. Ramlingam (1979) Seasonal variation in the air-born algae over a rural and an urban area. Current Science : 48: 956-957.
6. Ehrenberg, (1852), Dust showers and Red-Rain., Chamber’s Edinburgh Journal, No.432: vol-17.
7. Karnik, R.C., (1962) A contribution to the rain water forms and aerospora culture, 28 (10): 475-476.
8. Bernstain Leonard I. and Robbert S. Safferman (1970) Viable algae in house dust, Nature: (227): 851-852.
9. Herold E .Schlichting, (1975) Some sub-aerial algae from Ireland, phycol.J:10: 257-261.
10. Folger D.W, L.H.Burckle and B.C.heezen, (1967), Opal phytoliths in a North Atlantic Dust Fall, Science: 155: 1243-1244
11. S. (1984) Diatoms in the rain and snow, Int. Aerobiol. Newslet: 21: 5-10.
12. Pal U.C and S.C Santra (1986) Leaf inhabiting Blue Green Algal Flora of West Bengal. Ind. J. Bot: 9(2): 175-176.
13. Craig W.Schneider and Deniel C. M C Devit (2002) Are earthworms a possible mechanisms for air born dispersal of algae Vaucheria Northeastern naturalist, 9(2): 225-234.
14. Kamat N. D. and Harenkhedkar (1976) Bark algae of Nagpur, Maharashtra, Phykos : 15 (1&2) : 53-57.
15. Santra S.C. (1987) Airborne algae of Calcutta Metropolis. Phykos: (26): 71-74.
16. Sharma N. K , Surendra Sing and Ashwini Rai (2006) Diversity and seasonal variation of viable algal particles in the atmosphere of sub-tropical city in India. Environmental Research, 102 (13) : 252-259.