Indoor pollutant exposure among children with and without asthma in Porto, Portugal, during the cold season.

Considering the time spent in enclosed spaces, indoor air pollutants are of major interest because of its possible impact on health. However, to date, few studies have analysed the air concentrations of a large set of indoor pollutants of respiratory health relevance in dwellings, particularly in Portugal. This study aimed to measure the concentrations of air pollutants that are present in residential buildings and to investigate whether some clustering pattern of indoor air pollutants exists in the dwellings of children with (case group) and without asthma (control group). Measurements were taken in 30 and 38 dwellings of asthmatic and non-asthmatic schoolchildren, respectively, located in the city of Porto, Portugal, during the cold season (October 2012-April 2013), to assess the concentrations of 12 volatile organic compounds (VOC), aldehydes, PM2.5, PM10, bacteria and fungi. Toluene, d-limonene, formaldehyde, PM2.5, bacteria and fungi are widely present in dwellings, sometimes in relatively high concentrations in reference to WHO guideline values. Moreover, concentrations of CO2 exceeding 1000 ppm were often encountered, indicating that 70 % of all dwellings had poor ventilation (<4 L/s person). While exposures to common dwelling indoor pollutants are similar for schoolchildren with and without asthma, except for d-limonene levels, the identification and control of VOC and PM sources is important and prudent, especially for vulnerable individuals.