Comparteix

Public space

Risk Management in Urban Green Areas: Pollen Allergies and Accidents

CONTEXT

© enzozo / Shutterstock.com

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.

Read more

Given the sharp increase in respiratory diseases in cities, such allergic reactions need to be duly considered. It is calculated that 2 to 5% of the general population are allergic to some type of pollen. Recent studies show that people who live in urban environments suffer 20% more allergies than people who live in villages. Moreover, the excessive use of just a few species in green urban environments causes a high concentration of monospecific pollen in certain seasons of the year (Cariñanos & Casares-Porcel 2011).

It should also be taken into account that a larger proportion of the population will be affected by allergies in the coming years due to the extension of the pollination period brought about by temperature increases related to climate change. Other effects of climate change, such as droughts and heat waves, along with the presence of invasive plant species, will determine the type of plant life cultivated in cities, affecting the pollen that is produced and the corresponding allergies.

Allergies may be related to diseases of the respiratory system, such as asthma (breathing difficulties), rhinitis (runny nose) and conjunctivitis (runny eyes); skin diseases like eczema and hives, and severe reactions of rapid onset that jointly affect the skin, the respiratory system and/or the cardiovascular system (anaphylaxis).

Additionally, accidents may be caused due to falling branches or whole trees in the public space. These accidents may not be predictable in cases of force majeure (e.g. a storm), but in the majority of cases their causes can be addressed with suitable tree management.

 

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

Information only available in Catalan

 

 

 

LEGISLATION

STUDIES AND TECHNICAL DOCUMENTATION


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).

More information about addressing the Public Health Service: entornurbasalut@diba.cat

Date of last update:
dg., 09 de maig 2021 07:51:33 +0000