The risk of hidden “hot spots” with high levels of air pollution in Madrid (Spain)

Abstract

All urban areas at risk of breathing polluted air should be identified. In the outskirts of Madrid (Spain), there are roads with high traffic (highway A5) that are <5 meters away from nearby residential homes and schools with children and adolescents. The objective of this study is to ascertain the levels of NO2 in these populated areas. Several NO2 diffusion tubes were installed at a height of 3-m to measure NO2 concentrations in various locations of the A5 during the month of May 2022 (30 days). The four tubes located near the A5 measured a NO2 concentration of 49.7; 88.2; 56.8; and 60 μg/m³. The standard deviation and variation coefficient of the measurements were 0.5 and 2.7%, respectively. According to the WHO (2021), the admissible average annual limit is 10 μg/m³ and the daily limit is 25 μg/m³. This study aimed at measuring the concentration of NO2 near homes and primary and secondary schools located in a “toxic microenvironment” (close to the A5 in Madrid) found high and dangerous levels of NO2 impacting the health of the population. This is an area with a population of low socioeconomic level, which increases the impact on health.