Jin Wu, a researcher in environmental medicine, notes that even with lower levels of air pollution in Sweden compared to other countries, the connection between air quality and health is evident. "Air quality needs to be improved," he emphasized.
Motor neuron diseases are severe neurological disorders in which nerve cells responsible for voluntary movements gradually lose their functionality, leading to muscle atrophy and paralysis. Amyotrophic lateral sclerosis is the most common form of this disease, accounting for about 85-90% of all cases.
Environmental Factors
While the exact causes of these diseases remain unclear, there is an opinion that environmental factors may have an impact. New research confirms that air pollution may be one such risk factor.
In the study, 1,463 people in Sweden with recent diagnoses of motor neuron diseases were analyzed. They were compared with 1,768 siblings and more than 7,000 control participants from the general population. The scientists examined levels of pollutants (PM2.5, PM2.5–10, PM10) and nitrogen dioxide based on residential addresses over the past 10 years prior to diagnosis.
The average annual concentrations of these substances slightly exceeded the recommendations of the World Health Organization, while peak levels were significantly lower than in countries with high air pollution.
Increased Risk of Up to 30%
Prolonged exposure to polluted air, even at relatively low levels typical for Sweden, is associated with a 20-30% increased risk of motor neuron diseases. Moreover, patients living in regions with higher pollution levels experienced a faster decline in motor and pulmonary functions after diagnosis. They also showed an increased risk of death and a greater likelihood of requiring invasive ventilation treatment.
"Our results indicate that air pollution may not only contribute to the onset of diseases but also affect their progression," comments Caroline Ingre, adjunct professor of clinical neurology at the Karolinska Institute.
Data analysis focused solely on ALS patients showed similar results as for the entire group of motor neuron diseases.
Inflammation and Oxidative Stress
Scientists emphasize that the study does not allow for precise determination of the mechanisms behind this connection; however, previous research suggests that air pollution may trigger inflammatory processes and oxidative stress in the nervous system. Since this was an observational study, causality has not been established.
This study was based on data from Swedish registries and was funded by various organizations, including the Centers for Disease Control and Prevention (CDC) in the United States, the Swedish Research Council, and the Karolinska Institute.
