Air pollutants increase the risk of age-related macular degeneration
Severe air pollution can promote the development of age-related macular degeneration (AMD). The concentration of nitrogen dioxide (NO2) and carbon monoxide (CO) in particular appears to play a role, as a recent study from Taiwan shows. The authors of the study suspect that the exhaust gases in the air could almost double the risk of the disease.
Air quality influences risk of developing AMD
There are many possible causes of AMD: poor diet, damage from too much sunlight, a genetic predisposition or smoking tobacco - all of these things are at the top of doctors' list of suspects. Researchers led by Kuang-Hsi Chang from Tungs' Taichung Metro Harbor Hospital in Taiwan have now examined a new factor: traffic fumes. In their study "Traffic-related air pollutants increase the risk for age-related macular degeneration", the researchers established a connection between air quality and the frequency of the disease. Their result: people who live in a region with high levels of nitrogen dioxide pollution have almost twice the risk of developing the disease compared to subjects who live in an area with particularly low levels of pollution. Specifically, the researchers found a 91 percent increased risk (based on the most polluted quarter of the test participants compared to the least polluted quarter). A similar picture emerges with carbon monoxide: the risk of AMD is increased by 84 percent in areas with very high levels of carbon monoxide.
Risk for people in regions with high levels of traffic emissions
In order to establish the link between traffic-related air pollution and the risk of disease, the researchers calculated the concentration of nitrogen dioxide and carbon monoxide in the air of the test participants' respective places of residence for the period between 1998 and 2010. In total, this involved almost 40,000 people who were over 50 years old and lived in urban areas. These calculations were then geographically compared with the cases of disease that actually occurred in the following 10 years. The study authors interpret the significantly higher number of cases of disease in polluted regions that the researchers were able to determine in this way as evidence that air pollution can increase the risk of retinal diseases - they even speak of a significant connection.
Evidence of air pollution as an AMD trigger?
Even a significant connection between the amount of nitrogen dioxide and carbon monoxide should not lead to hasty conclusions, as the study authors explain: After all, the current experimental design is a study that can only establish a correlation, not a causality. In addition, the researchers were unable to take other risk factors into account and therefore could not adjust the calculations: For example, the study authors did not know whether other risk factors also occur unevenly across regions, for example with regard to the lifestyle or eating habits of the test subjects. This means that people from regions with higher levels of pollution are proven to get sick more often, but further studies are needed to show whether there is a direct cause-and-effect relationship between air pollution and retinal disease - although the probability can hardly be dismissed.
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