Introduction and objective:
In Finland and other northern countries, vegetable greenhouse workers are exposed to airborne dust and microbes all year round. The aim of the study was to assess respiratory exposure to dust, endotoxins and microbes, and to identify the risk phases of respiratory and skin exposure to promote safe working methods.

Material and methods:
Work in greenhouses was observed and recorded in a structured form. 23 personal samples and eight stationary samples of dust, endotoxins and viable microbes were collected from eight tomato or cucumber greenhouses in Finland. Dust samples were analysed gravimetrically. Endotoxins were analysed on filters by chromogenic Limulus amoebocyte lysate assay. Microbes were collected on filters, incubated and counted in three different culture media. Eight additional stationary samples of microbes were collected on a six-phase impactor.

The greenhouses were generally clean and well organised, but skin protection was deficient. The median of personal dust exposure was 0.24 mg/m3: 0.21 mg/m3 in the tomatohouses and 0.62 mg/m3 in the cucumber greenhouses. The mean level of bacteria in the tomato houses was 2.7 × 103 and in the cucumber houses 1.6×104. Those of fungi were 3.6 × 105 and 1.7 × 105 on Hagem and 8.1 × 105 and 1.9 × 105 on DG-18, respectively. The microbes made up about 1/10 of these values in the stationary samples. Very low concentrations of endotoxins were found in 5/23 air samples.

The clean appearance of the greenhouses was reflected in the low to moderate levels of dust. Risk phases of high exposure, such as lifting leaf debris, were identified. The microbe species were typical of this climate, and their levels were comparable to other greenhouse studies, but lower than in farming. Prevention among the foreign workforce is challenging due to the lack of a common language.

The authors warmly thank the greenhouse companies and their employees for their participation in the study. Financial support was gratefully received from the Finnish Work Environment Fund.
Ercilla-Montserrat M, Izquierdo R, et al. Building-integrated agriculture: A first assessment of aerobiological air quality in rooftop greenhouses (i-RTGs). Sci Total Environ. 2017; 598: 109–20. doi:10.1016/j.scitotenv.2017.04.099.
Couch JR, Grimes GR, Green BJ, et al. Review of NIOSH Cannabis-Related Health Hazard Evaluations and Research. Ann Work Expo Health. 2020; 64(7): 693–704. doi:10.1093/annweh/wxaa013.
Thilsing T, Madsen AM, Basinas I, et al. Dust, endotoxin, fungi, and bacteria exposure as determined by work task, season, and type of plant in a flower greenhouse. Ann Occup Hyg. 2015; 59(2): 142–57. doi:10.1093/annhyg/meu090.
Hansen VM, Meyling NV, Winding A, et al. Factors affecting vegetable growers’ exposure to fungal bioaerosols and airborne dust. Ann Occup Hyg. 2012; 56(2): 170–81. doi:10.1093/annhyg/mer090.
Madsen AM, Hansen VM, Nielsen SH, et al. Exposure to dust and endotoxin of employees in cucumber and tomato nurseries. Ann Occup Hyg. 2009; 53(2): 129–38. doi:10.1093/annhyg/men073.
Madsen AM, Tendal K, Frederiksen MW. Attempts to reduce exposure to fungi, β-glucan, bacteria, endotoxin and dust in vegetable greenhouses and a packaging unit. Sci Total Environ. 2014; 468–469: 1112–21. doi:10.1016/j.scitotenv.2013.09.014.
Madsen AM, Thilsing T, Bælum J, et al. Occupational exposure levels of bioaerosol components are associated with serum levels of the acute phase protein Serum Amyloid A in greenhouse workers. Environmental health: a global access science source. 2016; 15: 9. doi:10.1186/s12940-016-0090-7.
Koistinen T, Ruoppi P, Putus T, et al. Occupational sensitization to storage mites in the personnel of a water-damaged grocery store. Int Arch Occup Environ Health. 2006; 79(7): 602–6. doi:10.1007/s00420-006-0097-4.
Vandenplas O, Sohy C, D’Alpaos V, et al. Tomato-induced occupational asthma in a greenhouse worker. J Allergy Clin Immunol. 2008; 122(6): 1229–31. doi:10.1016/j.jaci.2008.07.035.
Lindström I, Karvonen H, Suuronen K, et al. Occupational asthma from biological pest control in greenhouses. J Allergy Clin Immunol Pract. 2018; 6(2): 692–4.e3. doi:10.1016/j.jaip.2017.08.034.
Kronqvist M, Johansson E, Kolmodin-Hedman B, et al. IgE-sensitization to predatory mites and respiratory symptoms in Swedish greenhouse workers. Allergy. 2005; 60(4): 521–6. doi:10.1111/j.1398-9995.2004.00687.
Bælum J, Birkhøj Kærstad M, Enkegaard A, et al. Health effects of predatory beneficial mites and wasps in greenhouses. Research report. Danish Environmental Protection Agency, Odense, Denmark, 2007.
Groenewoud GC, de Graaf in ’t Veld C, Van Oorschot-van Nes AJ, et al. Prevalence of sensitization to the predatory mite Amblyseius cucumeris as a new occupational allergen in horticulture. Allergy. 2002; 57(7): 614–9. doi:10.1034/j.1398-9995.2002.203511.
Suojalehto H, Hölttä P, Suomela S, et al. High Prevalence of Sensitization to Mites and Insects in Greenhouses Using Biologic Pest Control. J Allergy Clin Immunol Pract. 2021. doi:10.1016/j.jaip.2021.07.014.
Eduard W. Fungal spores: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting. Crit Rev Toxicol. 2009; 39(10): 799–864. doi:10.3109/10408440903307333.
Lindstrom I, Hölttä P, Suuronen K, et al. High prevalence of sensitization to bumblebee venom among greenhouse workers. J Allergy Clin Immunol Pract. 2021. doi:10.1016/j.jaip.2021.09.025.
Suojalehto H, Hölttä P, Lindstrom I, et al. Prevalence of tomato and cucumber sensitization among greenhouse workers. J Allergy Clin Immunol Pract. 2021. doi:10.1016/j.jaip.2021.09.038.
Andersen A. New sampler for the collection, sizing, and enumeration of viable airborne particles. J Bacteriol. 1958; 76(5): 471–84. doi:10.1128/jb.76.5.471-484.1958.
Liebers V, Bruning T, Raulf M. Occupational endotoxin exposure and health effects. Arch Toxicol. 2020; 94(11): 3629–44. doi:10.1007/s00204-020-02905-0.
Eduard W, Douwes J, Mehl R, et al. Short term exposure to airborne microbial agents during farm work: exposure-response relations with eye and respiratory symptoms. Occup Environ Med. 2001; 58(2): 113–8. doi:10.1136/oem.58.2.113.
Heldal KK, Eduard W. Associations between acute symptoms and bioaerosol exposure during the collection of household waste. Am J Ind Med. 2004; 46(3): 253–60. doi:10.1002/ajim.20058.
Malmberg P, Rask-Andersen A, Rosenhall L. Exposure to microorganisms associated with allergic alveolitis and febrile reactions to mold dust in farmers. Chest. 1993; 103(4): 1202–9. doi:10.1378/chest.103.4.1202.
Suuronen K, Koponen M, Hölttä P, et al. Working in a greenhouse. (access 2021.12.10).
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