Pollution Risk

This indicator is based on nutrient, pesticide and air pollution. Pollution is an important driver of biodiversity and ecosystem change throughout all biomes. While terrestrial ecosystems have been affected by nitrogen-phosphorous fertilisers, these have had a far more pernicious effect on the biodiversity of freshwater and marine habitats, leading to eutrophication and hypoxic or ‘dead’ zones that support no aquatic life. PM 2.5 is the annual global surface concentrations (micrograms per cubic meter) of all composition ground-level fine particulate matter of 2.5 micrometers or smaller. Exposure to high average concentrations of PM2.5 over time has been a reliable predictor of heightened mortality. There are multiple sources of air pollution, including emissions from industries, through the use of fossil fuels, agricultural processes, and vehicular emissions. The BRF only focusses on nutrient, pesticide (for terrestrial, freshwater and marine environments) and air pollution at this point. Terrestrial: FAO data has been used to calculate total nitrogen and pesticides per hectare of cropland. Please note that this source data is only available on a country level. Freshwater: McDowell’s projected median concentrations for total nitrogen concentrations during the growing season for catchments across the globe were used. Marine areas: Halpern’s impact score for nutrient pollution (from fertilizer runoff) has been used. Air: Hammer et.al. (2022) measured average concentrations of PM2.5 by combining Aerosol Optical Depth retrievals from multiple satellite algorithms. What does very high risk mean for this indicator? Areas of very high risk have high levels of nitrogen and pesticides per hectare of cropland (>77kg/ha; >5.9kg/ha, respectively); high total N concentrations in freshwater (>2.6mg/L); a very high nutrient & chemical pollution impact score in marine areas; experience more than 50 mg/m2 of PM 2.5.