A runny nose, sneezing attacks and swollen, inflamed mucous membranes: the runny nose is now a common plague in winter. But how bad it hits you does not only depend on personal disposition – air pollution also plays a role, as a study in 17 European cities now reveals. Accordingly, an increased level of particulate matter in the air increases the nasal congestion as well as the sneezing and irritation of the mucous membranes. A high exposure to nitrogen oxides, on the other hand, tends to make your nose run. According to the researchers, this also allows initial conclusions to be drawn about the mechanisms of these effects.
It affects almost everyone: between 20 and 50 percent of the world’s population is probably suffering from a cold at this moment. Rhinoviruses are usually the cause of this nasal inflammation, which is referred to in technical terms as rhinitis – highly contagious, but usually harmless cold pathogens. Typically, the runny nose first becomes noticeable through a constantly runny nose and sneezing fits. Later there are usually swollen nasal mucous membranes and a nose blocked by tough mucus. How severe these symptoms are, however, varies individually. Cold, among other things, seems to favor infection and the multiplication of rhinoviruses in the respiratory tract, but smokers are also usually more seriously ill than non-smokers. Researchers attribute the latter to the fact that the respiratory cells are overwhelmed by the simultaneous reaction to the toxins from the smoke and the activity of the viruses.
Influence of fine dust and nitrogen oxides
A research team led by Benedicte Jacquemin from the Barcelona Institute for Global Health (ISGlobal) has now examined the question of whether classic air pollutants such as particulate matter and nitrogen oxides can make a runny nose worse. The starting point for this was the observation that these air pollutants can worsen asthma. At the same time, rhinitis can also affect the severity of an asthma attack. “Rhinitis is closely linked to asthma, and this in turn is linked to air pollutants,” explains Jacquemin. “That’s why we wanted to know whether long-term exposure to air pollutants also plays a key role in rhinitis.” For their study, the researchers analyzed data from 1408 rhinitis patients from 17 European cities, including Paris, Barcelona, Antwerp, Umea and Erfurt. They used surveys to determine the severity of the symptoms and the course of the infection. They used data from a European air measurement project for air pollution at home.
The evaluation showed: Both the fine dust pollution and the concentration of nitrogen oxides in the air we breathe obviously play a role in the severity of the cold symptoms. Patients living in urban areas with higher PM10 and PM2.5 particulate matter levels suffered more from rhinitis than patients from less polluted areas. On average, each increase in PM2.5 values by five micrograms per cubic meter of air created a 17 percent higher risk of a severe course of the infection, as the scientists report. Specifically, this manifested itself in a greater irritation of the mucous membranes, more frequent sneezing and a greater congestion of the nose. An increased nitrogen oxide load, on the other hand, led to an increased mucus flow and also to increased constipation.
Oxidative stress for the mucous membrane cells
According to the scientists, it is clear that air pollution not only has a number of long-term health consequences, but can also affect the severity of acute runny nose. “This effect of these air pollutants on the severity of the symptoms is probably due to the fact that they cause oxidative stress, promote inflammation and activate the cell suicide program,” explains first author Emilie Burte from ISGLobal. Similar to tobacco smoke, the double exposure caused by the oxidative stress caused by the pollutants and the viral pathogens seem to overwhelm the cells of the mucous membranes. However, fine dust and nitrogen oxides appear to have different effects: “This could be because these pollutants have different mechanisms of action and therefore also cause different inflammatory reactions in the airways,” explains Burte. “But to confirm this hypothesis, we need more studies.”
Source: Emilie Burte (Barcelona Institute for Global Health (ISGlobal), Barcelona) et al., Journal of Allergy and Clinical Immunology
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