Nitrogen dioxide increases cardiorespiratory admissions in Torrelavega (Spain)

The objective of the study reported here was to analyze relationships between levels of air pollutants and emergency admissions for cardiorespiratory disease. Admission data from January 1, 1992, to December 31, 1995, were obtained from the Marques de Valdecilla University Hospital Admission Service; meteorological data (rainfall, temperatures wind speed, wind direction) were obtained from the National Meteorology Institute in Santander. Pollutant data on sulfur dioxide (SO2), hydrogen sulfide (H2S), total suspended particles (TSP), nitrogen oxide (NO), and nitrogen dioxide (NO2) were provided by the secretary of environment for the Cantabrian Regional Government. Rate ratios were estimated for each pollutant by Poisson regression; they were adjusted for meteorological variables. It was found that elevated NO2 increased by 20 percent the risk of having an admission for cardiorespiratory diseases; this effect was mainly due to respiratory diseases (rate ratio = 1.7, p < .001) and was negligible for cardiac diseases (rate ratio = 1.1, p = .28). In the one-pollutant model, elevated particulates and nitrogen monoxide were also related to admissions, but this effect disappeared when a five-pollutant model was used (p = .21 and p = 0.36, respectively. SO2 and SH2 did not show any relationship with admissions. Thus, nitrogen dioxide was the only pollutant the authors found to be related to emergency admissions for cardiorespiratory diseases. It is difficult to generalize from these results because of the small number of daily admissions and the variability in pollutant levels; therefore, more studies are necessary to improve knowledge about the relationship between air pollution and health in small towns.