Economic damage of plastic pollution: an integrated assessment across environmental domains in Oman

The economic impact of plastic pollution is poorly quantified, especially in the Gulf region. This study addresses this gap by quantifying the economic cost of plastic pollution in Oman. The integrated damage cost framework is developed based on the principles of contingent valuation, and implemented using five steps: 1) estimating the plastic fraction of municipal solid waste, 2) converting the plastic flow to an environmental leakage flow, 3) allocating the environmental leakage flow to four environmental sectors (terrestrial, freshwater, coastal/marine, and atmospheric/human exposure), 4) assigning a standardized unit damage cost, and 5) performing scenario and sensitivity analysis. In 2022, Oman produced 2.989M tons of municipal solid waste (MSW), with estimated losses of 34,989 tons, resulting in an annual damage cost of approximately $2.69M and a marginal loss of approximately $76.80 per ton. Terrestrial systems bear the largest share (42.4%, $1.14M), followed by freshwater (32.2%, $0.87M), coastal/marine (24.6%, $0.66M), and atmospheric pathways (0.8%, $0.02M). The analysis indicates that high stringency policies cut leakage from 5.6% to 2.3% and reduce total damage costs by nearly 60% to $1.10M by 2050. Sensitivity analyses indicate moderate uncertainty (±28.7%) around the baseline unit cost estimate and confirm that damages remain economically material across a range of leakage rates from 2.3% to 18.3%, without altering the ranking of domains. This finding further reinforces the economic rationale behind proper plastic management, as well as providing a model for damage cost assessment which can be applied elsewhere.