Abstract
Air pollution poses significant risks to environmental integrity and public health, making effective monitoring critical. Among nature-based solution (NbS), the use of plants as biomonitors has emerged as a complementary insight to conventional air quality monitoring methods. The objective of this review is to provide a comprehensive synthesis of 45 years of research on plant-based air pollution biomonitoring, summarizing global applications, methodological approaches, and gaps, with a particular focus on the model species Lolium multiflorum (ryegrass). Using ProKnow-C method, 1,400 relevant studies published between November 1979 and April 2025 were screened, of which 41 specifically addressed ryegrass. These studies reveal a significant increase in on the use of plants as biomonitors, expanding the range of species and target pollutants. However, the geographic distribution of studies is uneven, with a predominance in high-income countries, despite the high applicability of biomonitoring in regions with limited air quality monitoring infrastructure. The analysis identified > 960 different species used as biomonitors, with ryegrass being particularly favoured in active monitoring strategies due to its physiological resilience and standardized protocols. This review highlights the capacity of plant biomonitoring enables the assessment of spatial and temporal pollution patterns, contributing to the identification of hotspots and long-term trends, while also aligned with the One Health approach by quantifying pollutants and their risks to ecosystems. This study reinforces the value of expanding biomonitoring networks using plants as indicators to support more inclusive, accessible, and ecologically informed air quality assessments.