Quantitative analysis of air pollution and mortality in Portugal: Current trends and links following proposed biological pathways

A wealth of studies focusing on the relationships between negative health outcomes and short-term and long-term exposures to environmental risk factors have produced estimates of the burden of disease attributable to air pollution, which have led to the implementation of air pollution control strategies. However, the call to expand those studies, in terms of geographical units of analysis to produce more accurate estimates of the burden of disease in the different countries has been made. Studies of the specific environment-health relationship concerning air pollution in Portugal are scarce and rather descriptive. Therefore, this work assesses the trends both in atmospheric levels of pollutants including particulate matter (PM₁₀), ozone (O₃), nitrogen dioxide (NO₂) and sulphur dioxide (SO₂), and in mortality rates for diabetes, malignant neoplasms and diseases of the respiratory, digestive and circulatory systems, and explores the links between exposure to air pollutants and mortality, following proposed biological pathways and using inferential statistics methods, for the period 2010 to 2017 in Portugal. The following major conclusions were drawn: (i) despite a somewhat initial downward trend in PM₁₀ and a peak in O₃ levels, fairly constant air pollution levels were mostly observed; (ii) concomitantly, increases in age-adjusted mortality rates were significant for all diseases except diabetes; (iii) lower atmospheric levels of pollutants were observed in rural areas, when compared to urban areas, except for ozone; (iv) age-adjusted mortality rates were higher in rural regions, for diabetes, and in urban regions, for malignant neoplasms; (v) for a 10 μg/m³ increase in atmospheric levels of PM₁₀, regression analysis estimated an increase of 0.30% in the mortality rate for diseases of the respiratory, digestive and circulatory systems, and malignant neoplasms combined.