|Authors: ||L. Okushima, M. Saito, A. Ikeguchi, M. Ishii, S. Sase|
|Keywords: ||wider multi-span greenhouse, Venlo-type greenhouse, air quality, occupational health, food quality|
Air quality in greenhouses impacts the health of growers.
Floating dust particles and molds, which are important negative factors for air quality in greenhouses, were investigated under actual conditions.
Air was sampled from 10:00 through 14:00 from August 2000 to July 2001 in three types of greenhouses for producing tomatoes: a Venlo-type and two wider multi-span greenhouses, one of which used hydroponics culture and the other soil culture.
Using an optical particle counter, 2 L of air was drawn for 2 min and the number of dust particles greater than 0.3 μm in diameter was counted.
Then 420 L of air was drawn in 30 min and the molds in the air were cultivated at 30°C for 48 h and the number of mold colonies was counted.
The number of dust particles of more than 0.5 μm in diameter was about 107 per m3. The colony number of floating molds was approximately 200 CFU/m3. The orders of magnitude of these numbers of dust particles and molds were almost the same as those in the open field around the greenhouses.
The number of dust particles was significantly affected by the airflow through the ventilator openings, suggesting that air quality in the greenhouses was strongly influenced by the outside air quality.
Penicillium, Cladosporium, Aspergillus and Cylindrocarpon were common inside and outside the Venlo-type greenhouse.
In the winter, the number of mold species was less than in the open field, although the number of mold colonies was almost the same as in the open field.
It is considered that the mode of molds living in the greenhouse was different from that in the open field.
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