During these months affected by the pandemic due to SARS-CoV-2, information on mass media has highlighted the fact that Covid-19 was more diffused in highly air polluted areas suggesting possible links between air pollution and Covid-19.
In fact, looking at some Italian regions (Lombardy, Veneto and Emilia Romagna) where higher concentrations of air pollutants could be detected, the virus showed a more intense duffusion.
Despite many scientific publications highlighting the correlation between air pollution and cardiovascular and respiratory morbidity and mortality, so far, no strong data could support a relationship between pollution and mortality due to Covid-19.
A new research published on "Environmental Research Letters" has studied the relationship in USA between hazardous air pollutants (HAPs) exposure and US-based COVID-19 mortality. HAPs are a less studied group of pollutants, but include a wide array of known toxics such as volatile organic chemicals, metals, pesticides, etc. Results show that mortality in some not particularly populated, but highly polluted areas of the country, was higher in comparison with mortality in urban areas. Moreover, the outcomes of the study show a possible relationship between air pollutants and vulnerability of the population to get infected, while controlling for other variables such as, socioeconomic status, population health indicators, exposure to PM2.5 and ozone.
This study has important implications and demonstrates the need to not separate the research on human health from that on the environment. Human and environment health are strongly linked, as also the virologist Ilaria Capua - the One Health Center (Emergence Pathogens Institute, University of Florida) - claims, underlying the interconnections between the health of humans, animals, plants and the environment.
The Lancet Countdown report 2019 links climate change phenomena to an increased spread of infectious diseases but its impact on health is worsened, among many factors, also from emissions due to human activities.
Deforestation, urbanization and ecological and landscape fragmentation contribute to the transmission and spread of zoonosis.
The increase of epidemics is only one of the indirect and severe effects of emissions in the environment and of their impact on biodiversity and natural ecosystems.
In this context, which is the role of agriculture, of trees and how can agroforestry help?
Agriculture is one of the major causes of the disappearance of the 62% of the threatened or nearly threatened species and about 22% of the land area represented by biodiversity hotspots is threatened by agricultural expansion.
Once biodiversity changes have altered the dynamics of pathogen transmission, the likelihood of spillover to humans is high. Safeguarding biodiversity can prevent future pandemic zoonotic diseases.
As agroecological practices, agroforestry contributes to climate change mitigation and adaptation through the sustainable management of tree-based farming systems. Agroforestry can help to halt biodiversity loss and reduce pressure on forest ecosystems. Moreover, agroforestry prevents habitat destruction reducing soil erosion and flood events.
Agroforestry systems have shown to provide many benefits to the environment: reduction of runoff, raindrop interception and reduction of soil loss, reduction of agrochemicals and nutrient recycling, decrease of environmental impacts of fertilizers, soil fertility improvement, increase of use of belowground resources by crops and woody species, weed control, nitrogen fixation, carbon sequestration, improved soil biomass via tree fallow, accelerated mineralization and remediation of soils and shallow groundwaters. Agroforestry may also provide air quality improvement, greenhouse gas reduction, gaseous ammonia reduction and CO2 recycling, rise and stimulation of soil fauna, micro-climate stabilization, and pollination.
As regards to PM2.5, it is known that its finest portion can be stocked in and degraded by leaves and recent studies highlighted that the particulate removal is directly proportional to leaves biomass, peels and wax content.
Thus, trees and forests are extremely important as well as the proper choice of tree species is crucial. As trees are at the core of agroforestry systems and practices, European institutions must encourage and support any effort to invest in agroforestry strategies so that agroforestry can rise a leader role in providing agricultural solutions but also in improving the environment as well as human health and wellbeing.
Francesca Camilli
References
https://ilariacapua.org/one-health-center-of-excellence/
https://www.lancetcountdown.org/2019-report/