ANSES received a request from the ministries responsible for ecology and health to draw up a state of knowledge on pollens and molds in the ambient air of the most worrying overseas departments and regions in terms of of health and the main associated health effects. This request followed the publication by the Agency of an expert report on pollen in the ambient air, in 2014, and on mold in buildings, in 2016, in France.
Exposure of the population to pollens and molds present in the ambient air
No permanent device for measuring pollens and molds present in the ambient air currently exists in the DROMs. The data presented in the expert report made it possible to draw up a non-exhaustive list and to estimate the allergenic potential of pollens (filao, euphorbia, sugar cane, etc.) and des molds (cladosporium, aspergillaceae, etc.) present in the DROMs. They highlight qualitative and quantitative variations in pollens and moulds, linked to geographical and/or climatic factors. However, these are occasional and very localized data which do not make it possible to draw up a precise inventory of the species present in the DROMs or to precisely assess the exposure of the population to these biological agents.
Health effects potentially associated with pollens and molds in ambient air
The Agency notes that cases of allergic rhinitis are more numerous in Réunion and Guadeloupe than in mainland France. The same observation is made for asthma: the number of people with asthma, morbidity and mortality linked to asthma are higher in Guadeloupe, Martinique and Réunion than in mainland France. For example, the overseas departments (Reunion and the West Indies) have a higher prevalence of asthma among college students than the national average (between 11% and 12% in the overseas departments compared to 8 .6% in mainland France). However, these data are not sufficient to establish a link between these pathologies and exposure to pollens and molds in the ambient air.
Moreover, the absence of specific and reliable allergological tests does not allow a diagnosis to be made of the state of sensitization of the population to the pollens and molds characteristic of the DROMs.
Factors interacting with pollens and molds
In the current state of knowledge, it is not possible to determine the influence of meteorological conditions or atmospheric pollution on the production of pollens, the development of molds and their dispersion in the ambient air of the DROMs.
With regard to molds in tropical environments, their development and dispersion in the ambient air are first favored by certain factors: relative humidity, rainfall, temperature, wind, tropical cyclones, etc.
Even if there is an association between sand mist, atmospheric pollution or certain meteorological or climatic factors and health indicators, it is not possible, in the current state of knowledge, to assess the interaction between these factors and the pollens and molds present in the ambient air of the DROMs.
The Agency’s recommendations
Faced with these findings, the Agency recommends assessing the exposure of the general population of the DROMs to pollens and moulds, in particular:
- by setting up a system for measuring the pollen and mold present in the ambient air, taking into account the distribution of the population, the plant biodiversity of these territories and the climatic conditions. The implementation of measurement sensors should be done, as a priority, in areas with high population density such as urban areas;
- by pursuing research and development of new capture and analysis methods that would make it possible to identify specific species of the DROMs.
The Agency recommends improving knowledge of the state of health of the population potentially exposed to pollens and molds present in the ambient air, in the DROMs. For this, various avenues are proposed: implementation of epidemiological studies, development of allergological tests specific to pollens and molds in the DROMs, establishment of a network of sentinel doctors.
It is also necessary to improve knowledge of the factors interacting with pollens and molds in the ambient air of the DROMs: in particular, it is a question of evaluating the influence of meteorological conditions and climate change or pollution. atmosphere on the production of pollens, the development of molds and their dispersion in the ambient air. The Agency also recommends continuing research work on other outdoor exposures, for example by conducting physicochemical and biological characterization studies of sand mists to find out their composition.
The Agency also renews its recommendation to set up studies aimed at assessing the nature and abundance of molds in buildings in the DROMs, which it issued as part of its expertise on molds in buildings published in 2016.
With regard to plants emitting pollen of concern for health, the Agency recommends:
- to limit the planting of plants already known to be allergenic in mainland France or in other countries;
- to decline, in the regional environmental health plans of the DROMs, actions 8, 9 and 10 “for monitoring, prevention and reduction relating to the presence of allergenic pollens and/or molds in the air” included in the National Plan environmental health 2015-2019.
Finally, the Agency recommends setting up prevention and information actions for the population on pollens and moulds. It also recommends encouraging the setting up of coordination of all players in the field (regional health agencies, approved air quality monitoring associations, doctors, pharmacists, biologists, botanists, etc.) in order to promote the emergence of common actions and the sharing of information on this health issue.