Description of air quality and environmental characteristics in primary school classrooms in the Community of Madrid.

Introduction: Air quality in schools is a concern at the European level, and few data have been published on the subject in the Community of Madrid.

Material And Methods: We conducted a longitudinal descriptive study on the presence and distribution of pollutants in four schools in Madrid selected on account of their location, exposure to traffic and proximity to green areas. We measured pollutants and assessed environmental characteristics in primary school classrooms. We measured pollutants with sensors over five data collection campaigns, each lasting two weeks. The obtained data were analyzed with the R software. We calculated the median, range and percentage of exceedance of recommended thresholds and assessed environmental conditions.

Results: We found levels of 2.5 µm particulate matter (PM) above the recommended threshold in 40%-70% of the measurements. Volatile organic compounds (VOCs) exceeded the recommended threshold in April in 41.52% of the measurements. The level of CO exceeded the recommended threshold in three of the campaigns. There was broad variation in ultrafine particles. Temperature, CO, VOCs, PM 1, PM 0.3 and PM 2.5 levels were higher in occupied classrooms. Humidity was positively correlated to PM 0.3, PM 1 and PM 2.5 levels and negatively correlated to ultrafine particle levels.

Conclusions: This is the first study to assess indoor pollutants and their concentration in schools in the Madrid region. We found levels of CO, PM 2.5 and VOCs exceeding the currently recommended thresholds.