Occupational Exposure to Bacteria, Molds and Particulate Matter in Citrus Greenhouses

Background and Objectives: Citrus farming is common in the southeastern part of the US. 70% of our countries citrus fruits are grown in Florida and farmers in Georgia are adopting citrus farming. Citrus trees are grown in climate controlled greenhouses with associated exposure risks of molds, bacteria, and organic dust particles. The objective of this study was to assess the indoor air quality in several citrus greenhouses.

Methods: Biostage viable impactor was utilized for air sampling which comprises an inlet cone, an impactor stage, and a base that holds an agar plate, where microorganisms (molds and bacteria) are collected. Airborne particles, including PM0.5 and PM1 (closer to bacterial and fungal cell sizes) were monitored using a 6-channel (0.3, 0.5, 1.0, 2.5, 5.0 and 10 µm) particle counter with graphical interface which can stores up to 5000 sample records on micro SD card. Atmospheric temperature, and relative humidity were measured with the same device. An anemometer measured the wind speed.

Results: Preliminary data showed a range of 10(1) to 10(2) CFU/m(3) of culturable bacteria and 10(2) to 10(3) CFU/m(3) of culturable molds. The concentration ranges for 0.5 µm and 1.0 µm articles were 10(4)-10(5) particles/m(3) and 10(4)-10(6) particles/m(3), respectively. PM1 and PM0.5 were found in higher concentrations in green houses with mature crops.

Conclusion: Preliminary data indicates that high levels of fine particles were present in greenhouses with low airflow and higher maturity of plants. The concentrations of bacteria and molds were relatively lower compared to other ambient agricultural activities.