Risk Management in Urban Green Areas: Pollen Allergies and Accidents - Entorn Urbà i Salut

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Risk Management in Urban Green Areas: Pollen Allergies and Accidents

CONTEXT

Green urban spaces are one of the elements that can help moderate the microclimate in the squares and streets of cities. They contribute to the reduction of air pollution, generate thermal comfort and may attenuate excessive noise (e.g. shade, heat reduction thanks to the evapotranspiration of water from plants). There is also an abundance of scientific evidence on the benefits of urban green spaces for the physical and mental health of adults and children. However, it must be taken into account that urban green spaces may accentuate pollen allergy problems and cause accidents due to falling branches, making suitable management of such spaces a necessity.

The reproductive strategy of urban green space species gives rise to the generation of spores and pollen that are dispersed into the air and enter the human body through the mucous membranes of the respiratory system and/or the eyes. In sufficient amounts, spores and pollen may trigger allergic reactions in sensitive individuals.

OBJECTIVE

• Prevent to the extent possible any situations that may generate allergic reactions by either restricting the use of certain species or establishing tree management protocols to avoid the pollination stage.
• Reduce the likelihood of harm to people and goods caused by falling branches and trees.

PROPOSALS AND RECOMMENDATIONS

• When choosing which species to plant, prioritise indigenous species that produce less pollen and those that do not make use of aerial pollination (self-pollination, insects, etc.). Indigenous species are usually less prone to producing allergies (WHO, 2016).
• Atmospheric contaminants may increase allergic reactions to pollen (Cariñanos & Casares-Porcel 2011).
• The seasons should be taken into account in efforts to prevent the effects of extreme temperatures. It is a good idea to choose deciduous species, as they let the light of the sun through in the winter and protect us from it in the summer.
• Moreover, good planning should take into account the environment and the space where they are to be planted, the dimensions and shape of the species, and the functions and management of the green space. In this sense, the species least prone to falling branches should be selected in areas with a high density of traffic and/or people.
• Consult a botanical specialist when choosing the best species to plant from the risk perspective.
• Ensure that male and female dioecious trees are planted in equal numbers. Females may generate problems in terms of falling fruit, stronger odours and the generation of a slippery surface, but males produce more pollen. It is therefore important to strike a balance (Cariñanos & Casares-Porcel 2011).
• To reduce the accident rate, prepare a risk control and management plan for urban trees in the municipality that establishes the protocols to be followed and their periodicity, including the pruning of each species of tree and the removal of fallen leaves and/or fruit from the pavement.
• It is also important to train the staff who carry out tree maintenance to detect significant symptoms and decide on the actions to be taken.
• Monitor the condition of the trees, especially after storms or torrential rain in periods of drought.

REFERENCE EXPERIENCES

LEGISLATION

• Real Decreto 1311/2012, de 14 de septiembre, por el que se establece el marco de actuación para conseguir un uso sostenible de los productos fitosanitarios.
• La OMS avalua 5 insecticides i herbicides organofosfats. L’herbicida glifosfat i l’insecticida malation i el diazinon han estat classificats com a probablement cancerígens (Grup 2A). L’insecticida tetraclorvinofos i el paration han estat classificats com a possiblement carcinogènic pels humans (Grup 2B).

STUDIES AND TECHNICAL DOCUMENTATION

• Ajuntament de Barcelona. Guia de Jardineria Sostenible. Guies d'Educació Ambiental.
• osch, Joaquim; Xavier Candela; Gerard Jané. Plec de prescripcions tècniques de manteniment dels espais verds. Diputació de Barcelona.
• Diputació de Barcelona. Cercador d'arbrat viari. 
• Diputació de Barcelona, 2012. Guia per a la selecció d'espècies de verd urbà: arbrat viari. Documents de Treball.
• Diputació de Barcelona, 2015. Guia per a la selecció d'espècies de verd urbà: Jardineria. Documents de Treball.
• Diputació de Barcelona, 2018. Guia per la redacció de plans directors del verd urbà. Col·lecció Eines.
• Belmonte Soler, j. 2009. Informe Aerobiologia de Barcelona 2009. Institut de Ciència i Tecnologia Ambientals, ICTA.
• Nature Base Solutions, Programa de la Comissió Europea.  
• The WHO Regional Office for Europe, 2017. Urban green spaces: a brief for action. 
• Filip, Gregory M., et al., 2014. Field Guide for Hazard-Tree Identification and Mitigation on Developed Sites in Oregon and Washington Forests. U.S. Department of Agriculture (USDA) Forest Service.

Scientific papers:

• Cariñanos, P., Casares-Porcel, M., 2011. Urban green zones and related pollen allergy: A review. Some guidelines for designing spaces with low allergy impact. Landscape and Urban Planning, 101(3).

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