Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Environmental impact of pharmaceuticals and personal care products wikipedia , lookup
Air well (condenser) wikipedia , lookup
Water testing wikipedia , lookup
Freshwater environmental quality parameters wikipedia , lookup
Wastewater discharge standards in Latin America wikipedia , lookup
Water quality wikipedia , lookup
Water fogging and misting systems – are they a risk to human health? ISSUE NUMBER: 2001/5 Thousands of nursery workers have been, and continue to be, exposed to the fine aerosols of water from both fogging and misting systems. Does this exposure put these workers at risk of contracting Legionnaire’s disease or other water-borne human diseases? Dr David Douglas, a consultant in occupational and environmental health, reports that good quality water (that is treated town water, clean rain water or water that has been disinfected properly) will not contain bacteria, fungi or viruses that are harmful to either plants or humans. The Australian horticultural industry has, for several decades, been using water-fogging systems to assist in temperature control, and water-misting systems for watering seedlings. Both systems produce fine aerosols of water, with droplet sizes usually less than 60 microns. Such droplets are too large to be inhaled into the deep lungs of humans, but can readily reach the upper airways and bronchial passages. To date, there have been no written or anecdotal reports of adverse human health effects attributed to such exposure. Nevertheless, the Nursery & Garden Industry Australia (NGIA) has received inquiries about the potential for fogging and misting systems to cause Legionnaire’s disease or other human diseases. Fogging and misting systems will not cause human health problems as long as the water being used does not contain bacteria, fungi or viruses and/or is disinfected properly. water-borne Legionnaire’s disease, which is a pneumonia-like illness, was first recognised when a serious outbreak occurred at an American Legionnaires’ Convention in Philadelphia in 1978, but it was not a new disease at that time. © NGIA – The Nursery Papers – Issue no 2001/5 – Page 1 The causative organism (Legionella pneumophila) is widespread in the environment as a common contaminant of water sources. Outbreaks of Legionella pneumonia in Australia have mostly been associated with contaminated water in cooling towers and spa baths, with case reports also implicating exposure to potting mixes. It is possible that the water used in fogging and misting systems could contain Legionella bacteria, especially if: (i) drawn from surface supplies such as dams, creeks and rivers; (ii) drawn from recycled water sources, or (iii) drawn from water stored at 20-45˚C. Similarly, it is possible that the fogging and misting systems could contain other bacteria harmful to humans, such as E. coli, that may result in gastrointestinal diseases. However, the probability of bacteria contaminating fogging and misting systems can be eliminated if the quality of the water delivered by the fogging and misting systems is maintained so as to provide optimal, disease-free, growing conditions for plants. The best water for plants, that is, water that is free of plant pathogens (bacteria, fungi and viruses), will also be free of human pathogens. The need for good quality water, and detailed information on the many different ways of achieving it, has been well documented. Keith Bodman, director of horticulture, environmental sciences and rural studies, Challenger TAFE, WA, claims: “The quality of your water will determine what crops can be successfully grown, the methods of cropping; and the types of treatment needed to make it suitable for use, re-use, or discharge from the site.” The provision of good quality water is a fundamental but potentially complex issue. The reader is advised to refer to the publications listed below and consult with the relevant Nursery and Garden Industry associations and/or state authorities. Periodic testing of water being used in fogging and misting systems for plant and human pathogens can also help determine the water quality and/or the effectiveness of the water treatment. Further reading Rolfe, Chris, et al. (2000), Managing water in plant nurseries, second edition. NSW Agriculture. Bodman K. (1997), ‘Improving water quality’. Ornamental Update (Volume 12 number 3), Queensland Department of Primary Industries. ‘Using ultra violet radiation and chlorine dioxide to control fungal plant pathogens in water’, The Nursery Papers, 1996 #05. ‘Water disinfestation – chloro-bromination and ozone systems get the thumbs up!’ The Nursery Papers, 1997 #08. ‘Slow Sand Filtration (SSF) for water treatment in nurseries and greenhouses’, The Nursery Papers, 1999 #03. The bottom line Town water that has been treated and used for domestic household purposes (not ‘Grey Water’) is not likely to cause any plant or human health problems. Surface water (dam, river, creek or recycled water) should be treated for plant pathogens to ensure optimum plant growth. This treatment, assuming it is regularly monitored and effective, will also prevent possible human diseases. Acknowledgements The author, Dr David Douglas, Douglas Consulting Australia, is grateful for the assistance provided by Mr D. Randall of Floranda Flowers, Cabariah, Queensland; and by Ms C. Lane of GrowSearch, Department of Primary Industries, Queensland. If there remain any doubts about the quality of the water being delivered by fogging or misting systems, then the water should be tested for Legionella bacteria and other human water-borne pathogens by the relevant state public health laboratories. Page 2 – © NGIA – The Nursery Papers – Issue no 2001/5