Modeling trend changes of mean annual exposure to PM 2.5 particles in the Middle East countries via growth mixture models

Rapid economic expansion, industrialization, urbanization, and construction in the Middle East have led to an increase in ambient air pollution. This study was devoted to model the 28-year trend changes of the mean annual exposure to particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5 particles) in the Middle East countries. Data used in the current study includes the mean annual exposure of PM2.5 air pollution (micrograms per cubic meter) for the Middle East countries during 1990 to 2017 that is compiled by the World Bank. To identify different longitudinal patterns of PM2.5, the researchers fitted growth mixture model with a different number of clusters in Mplus 7.4. The overall trend of annual exposure was rising during 1990 to 2017. Both the Bayesian information criterion and likelihood ratio test confirmed that the 2-cluster model is the best and the entropy of 0.99 confirmed a good quality in the cluster memberships. The observed pattern of exposure to PM2.5 in cluster 1, including Bahrain, Egypt, Iraq, Kuwait, Qatar, Saudi Arabia, and Yemen, was rising over time. On the other hand, countries in cluster 2, including Cyprus, Iran, Israel, Jordan, Oman, Lebanon, Syria, and Turkey, experienced a constant level of exposure to PM2.5 from 1990 to 2017. The main longitudinal patterns of PM2.5 were identified by the proposed model. Given the harmful effects of exposure to PM2.5 particles, taking into account more investigation in the future is highly suggested.