Attempts to reduce exposure to fungi, β-glucan, bacteria, endotoxin and dust in vegetable greenhouses and a packaging unit

Abstract

Indoor handling of large amounts of plant materials occurs in different occupational settings including greenhouses and causes exposure to bioaerosols. The bioaerosol components fungi, β-glucan, bacteria and endotoxin are involved in different airway symptoms and health effects can be dose-dependent. Therefore, there is a persistent need to reduce exposure. The aims of this study were to identify tasks causing exposure and to evaluate preventive measures aimed at reducing exposure of greenhouse workers to bioaerosols, and to study factors affecting the exposure. We have focused on different exposure scenarios; one with high short-term exposure found during clearing of old cucumber plants; the other with long-term, mid-level exposure found during tomato picking, leaf nipping, stringing up tomato plants, and packaging of cucumbers. Clearing of non-dried cucumber plants compared with clearing of dried cucumber plants significantly reduced the exposure to dust, endotoxin, bacteria, fungal spores and β-glucan. More endotoxin and fungi are emitted and more of the emitted particles were of respirable size if the leaves were dried. Along the cucumber packaging line, exposure levels were highly specific to each personal subtask. The subtask 'unloading of cucumbers' was the source of exposure making task ventilation or shielding of the process a possibility. Elimination of leaf debris on the floor reduced the exposure to fungi significantly. However, leaf debris on the floor did not contribute significantly to the exposure to dust, endotoxin and bacteria. Furthermore, to eliminate leaf debris, it had to be cleared away and this was associated with a higher exposure to dust and endotoxin. The age of the plants affected the exposure level to bioaerosols with higher exposures from old plants. In conclusion, different tasks and subtasks cause very different exposure levels. It is possible to reduce exposure by identifying subtasks causing the exposure and by modifying work processes, e.g., not drying out of plants.

Fungal Bioaerosol Exposure and its Effects on the Health of Mushroom and Vegetable Farm Workers in Taiwan

“…However, we found that the fungal concentrations in the personal samples were consistently higher than those in the area samples, although the difference was not significant, probably because of a small sample size. Similar results were observed in a Danish study conducted in vegetable greenhouses (Madsen et al, 2014). Because workers often disturbed bioaerosol sources during activities, such as mixing material, picking vegetables, digging soil, and packaging, thus increasing the personal exposure concentrations.…”

“…Various studies have evaluated bioaerosol exposure on agricultural farms (Chang et al, 2002;Lee et al, 2006;Matkovic et al, 2009;Madsen, 2011;Hansen et al, 2012;Lee and Liao, 2014;Madsen et al, 2014;Viegas et al, 2014;Chow et al, 2015); of these, only a few have been conducted in Taiwan (Chang et al, 2002;Lee and Liao, 2014). In addition, studies focusing on the health risks of occupational fungal exposure on farms are scant (Yoshikawa et al, 2007;Adhikari et al, 2011;Ampere et al, 2012).…”

Building-integrated agriculture: A first assessment of aerobiological air quality in rooftop greenhouses (i-RTGs)

“…Previous studies showed that cleaning the aisles after leaf nipping resulted in a significantly higher exposure to endotoxin (Madsen et al, 2014). In this study, days when a sweep was performed did not always reflect an increase in the concentrations of Oidium or Torula spores (Fig.…”

“…In greenhouses, the growth conditions for plants are optimized to increase crop yields (Hansen et al, 2010). However, indoor handling of large amounts of plant materials occurs in different occupational settings, including greenhouses, and causes exposure to bioaerosols (Madsen et al, 2014). As indoor air is highly dynamic, studies have been carried out to examine indoor air quality, especially for occupational and public health purposes (Bonetta et al, 2010).…”

“…The i/o ratio for fungi observed in greenhouses where flowering plants are cultivated in the Midwestern USA in winter was also >1 (Adhikari et al, 2011). In this cases, the introduction of outside air into the greenhouses was recommended in order to dilute the indoor bioaerosol exposure (Madsen et al, 2014).…”