Dataset of aggregated indoor and outdoor daily environmental variables for three school sites impacted by air purifiers

This dataset contains indoor and outdoor air quality measurements, along with environmental parameters, collected through low-cost sensors between November 2023 and June 2024 at 3 school locations of interest in the city of Milan, Italy. Indoor values from multiple low-cost sensors have been aggregated to a unique value at the daily level for each location. Note that in each location, professional air purifiers were located in some indoor environments where measurements were taken. Outdoor pollution levels are sourced from the European Environmental Agency (EEA) database. We interpolate daily averages of fine particulate matter (PM2.5) and hourly averages and maxima of ozone (O3) measured at the two closest background air quality stations to each location of interest by applying inverse distance weighting. They provide indicative levels of pollution at the city level. ---Variable Name Descriptionid: Unique identifier of location to which the environmental data referdate: Timestamp of the daily observation (format: YYYY-MM-DD)ind_pm25: Daily indoor fine particulate matter (PM2.5) concentration in micrograms per cubic meter (µg/m³)ind_pm10: Daily indoor coarse particulate matter (PM10) concentration (µg/m³)ind_co: Daily indoor carbon monoxide (CO) concentration in parts per million (ppm)ind_co2: Daily indoor carbon dioxide (CO2) concentration (ppm)ind_temperature: Daily indoor air temperature in Celsius degrees (°C)ind_humidity: Daily indoor relative humidity in percentage (%)ind_pressure: Daily indoor atmospheric pressure in hectopascals (hPa)out_mean_pm25: Daily outdoor average PM2.5 concentration (µg/m³) from nearby air quality stationsout_mean_o3: Daily outdoor average ozone (O3) concentration (µg/m³)out_max_o3: Daily outdoor maximum hourly ozone (O3) concentration during the day (µg/m³)