Air pollution linked to increased hospitalizations for kidney disease and sepsis The health effects of air pollution may be more serious than thought. Air pollution caused by so-called fine particulate matter has been linked to an increased risk of several diseases, including heart attacks, strokes and breathing difficulties. Fine particulate matter is tiny particles of solid and liquid pollutants smaller than 2.5 micrograms, also known as PM2.5. These tiny particles are considered harmful because they can be inhaled into the lungs and absorbed into the bloodstream. Researchers examined 95 million hospitalizations in the United States for people over the age of 65, and they found that elevated PM2.5 increased the chance of hospitalization not only for heart disease and lung disease, but also for other illnesses not previously associated with air pollution, including sepsis, urinary tract infections and kidney failure. The researchers estimate that a very small increase in airborne PM2.5 may be associated with an additional 5,692 hospitalizations and 634 deaths per year in the United States. Due to the limitations of the type of study conducted, we could not determine that pollution was the direct cause of the increase in hospitalizations. However, this study does provide evidence that air pollution has a negative impact on health, and it may inform the international air pollution guidelines that are currently being updated. The researchers who conducted the study were from the Harvard School of Public Health in the United States, Tsinghua University in China and the Swiss Data Science Center. The study was funded by the National Institutes of Health and the U.S. Environmental Protection Agency. It is published as open access in BritishMedicalJournal and is therefore freely available online. Similar to previous studies, the researchers found an association between elevated PM2.5 levels and an increased risk of hospital admissions for heart failure, pneumonia, chronic obstructive pulmonary disease (COPD), heart attack, Parkinson’s disease, complications from diabetes and several other conditions. However, they also found an increase in the incidence of other relatively common diseases that were not previously associated with PM2.5 pollution. These included: sepsis, water and electrolyte balance disorders, kidney failure, urinary tract infections, and skin and tissue infections. The findings “provide evidence for a timely revision of WHO guidelines”. But the study has limitations in that it does not tell us whether the conditions identified are directly related to contamination or whether other factors are involved. For example, in some cases, activities such as smoking, alcohol consumption and physical activity may also lead to hospital admissions, and these conditions may vary depending on the level of air pollution. Overall, PM2.5 pollution (mainly from vehicle emissions and burning chemical fuels) is harmful to health.