Radiofrequency electromagnetic field effects on green roof ecosystems: an unexplored topic.

This new interdisciplinary review summarizes the existing literature on green roof ecosystems and the effects of electromagnetic fields on plants and insects. It also provides power density measurements on roof surfaces. The growth in popularity of green roofs is closely tied to the global expansion of wireless communication technologies.

In Phase 1, the authors conducted a narrative synthesis of empirical radiofrequency electromagnetic field (RF-EMF) measurements taken on urban rooftops, covering the frequency range from 0.7 to 3.8 GHz. The synthesis was based on a comprehensive literature review, from which the authors selected 20 articles. In Phase 2, the researchers conducted a thematic synthesis of published findings on the biological and ecological effects of RF-EMFs on plants and insects. Following the literature review, they included 34 studies.

The review of the literature shows that RF-EMF levels on rooftops are significantly higher than at ground level. Some studies report that RF-EMF levels on rooftops are up to 150 times higher than at ground level, while others cite differences of 30 to 100 times higher. The two most recent studies found an average difference of 16 times higher. These levels vary depending on the height of the building (and the base station), the urban environment, the wireless communication technologies used (1G to 5G), and the frequency bands employed. Overall, the cited studies demonstrate that RF-EMF exposure on rooftops near base station antennas is highly variable and often exceeds several tens of milliwatts per square meter. Levels exceeding 10,000 mW/m² only occur at very close range, directly in front of base station antennas. For a standard 900 MHz antenna, this distance ranges from 1 to 4 m, depending on the radiated power and antenna gain. These results suggest that thermal effects on green roof plants and animals are likely minor and rare. However, flying insects can come into close proximity to transmitting antennas and receive thermally relevant doses. Due to the limited number of high-quality studies examining invertebrates under RF-EMF exposure, several review articles conclude that definitive conclusions on this topic are difficult to draw. Two recent review articles acknowledge the shortcomings of some studies and discrepancies between RF-EMF exposure in laboratories and the environment. These articles assert with greater certainty that RF-EMF exposure in insects is associated with harmful, non-thermal biological effects. It has long been known that RF-EMF is a genuine environmental stimulus for plants. However, little is known about the quantitative relationship between plant responses and RF-EMF exposure. The accumulated evidence is insufficient to define the nature of the relationship between the magnitude of the plant response and the level of EMF power density.

Ecosystems on green roofs near base station antennas may be exposed to RF-EMF levels significantly higher than those at ground level. Since plants are fundamental to these ecosystems, how they respond to RF-EMF exposure is especially relevant. These responses can be broadly divided into two categories. The first category includes stress effects, such as increased production of reactive oxygen species (ROS) and changes in cytosolic calcium (Ca²⁺) signaling. The second category includes direct morphological effects, such as decreased photosynthetic pigments and shorter roots or stems. Chronic ROS and Ca²⁺ stress signals lead to phenotypic adaptations that are well documented in the literature on plant stress. These adaptations are accompanied by slower growth and promote vegetative reproduction at the expense of seed production. Since bees pollinate some plant species on green roofs, these behavioral effects provide an additional pathway through which RF-EMFs can influence green roof ecosystem functioning, regardless of their direct effects on plants.

The authors present compelling arguments and propose concrete ways to use urban green roofs as models to study the ecological impacts of RF-EMFs from mobile phone base stations. This suggests that research projects of this nature are already planned or underway.

Editor’s note:

It is encouraging to see scientists from diverse backgrounds – two botanists who are experienced in the effects of electromagnetic fields on plants and a biophysicist who specializes in modeling electromagnetic radiation absorption (in insects) – collaborating and advocating for a research area that has received little attention to date. The authors convincingly argue that urban rooftops are relevant and well-suited models for investigating the effects of RF-EMFs. Hopefully, the authors will conduct (semi-)field studies in urban rooftop environments. One minor drawback is that, although RF radiation levels on urban rooftops are generally higher than at ground level, several recent studies and reviews have found stronger EMF effects at lower doses (e.g. 5 V/m) than at much higher doses (e.g. 40 V/m) [1, 2]. Therefore, future experiments should use a wide range of EMF power densities or field strengths. (AT)

1. Brzozek C, Mate R, Bhatt CR, Loughran S, Wood AW, Karipidis K (2024). Investigating the impact of anthropogenic radiofrequency electromagnetic fields on animals and plants in the environment: Analysis from a systematic map. International Journal of Environmental Studies, 81(5), 2343-2358. https://doi.org/10.1080/00207233.2024.2375861

2. Bundesamt für Strahlenschutz (BfS) (2026). Einfluss hochfrequenter elektromagnetischer Felder auf Pflanzengesundheit und Wachstum: Vorhaben 3622EMF404. Ressortforschungsberichte zum Strahlenschutz-261/26. https://doris.bfs.de/jspui/handle/urn:nbn:de:0221-2026060160272