1- Serviço de Imunoalergologia, Hospital de Dona Estefânia, Centro Hospitalar deLisboa Central, EPE, Lisboa
2- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa
3- Instituto Nacional Dr. Ricardo Jorge
3rd International Congress on Environmental Health – Porto (Comunicação Oral)
INTRODUCTION: In modern society, children spend most of their time indoors (up to 85%), at home or in children day care centers (DCC), and they are particularly vulnerable to the effects of indoor air quality (IAQ). Different studies have shown that IAQ and ventilation are associated with respiratory symptoms, allergy and infections. The evaluation of metabolites of nitric oxide (NO), namely nitrates (NO3-) in exhaled breath condensate (EBC), is a good biomarker of airway inflammation. Studies evaluating the relationship between individual exposure to indoor pollutants and airway inflammation are scarce, particularly in preschool-age children.
OBJECTIVES: Evaluate the relationship between airway inflammation parameters in EBC of children attending children day care centers and indoor air quality (IAQ) in these institutions.
MATERIALS AND METHODS: In the 2nd phase of ENVIRH project, EBC samples were collected, using a disposable device (RTube - Respiratory Research Inc., Austin, TX, USA), from a group of preschool-age children. Exhaled breath is saturated with water vapor, which can be condensed by cooling and used to sample a wide range of mediators. Children aged between 4 and 5 years were invited to participate but a limit of 100 EBC collections was established due to budgetary constraints. EBC was collected over a 15 minute period and samples were frozen at -40°C. Airway inflammation biomarkers (pH and total nitrites/nitrates) were determined. pH was measured through a glass microelectrode (Hi 9025, Hanna Instruments, Italy) after sample deaerating with argon. Nitrate levels were determined through a chemoluminescence method by reaction with vanadium trichloride and release of nitrous oxide with a Sievers 280i NOATM analyser (Sievers Instruments, Inc., CO, USA). From the several IAQ analyzed parameters, main ones were:PM10, VOCs, house dust mites, fungi, bacteria, temperature and relative humidity. Evaluation was carried out under typical occupation conditions, during everyday activities. Chosen methods to evaluate chemical parameters were based on the Technical Note NT-SCE-02 document that establishes the proper methodologies to perform indoor air quality audits in buildings, in accordance with published legislation and reference methods were used for PM10 and VOCs. Thermal comfort, and bacteria and fungi quantifications followed accredited methods that comply with ISO and EN standards. No standards or reference methods are described to quantify house dust mite antigens. Dust samples for house dust mite evaluation were collected on filters using a vacuum cleaner with a DustreamTM collector (INDOOR Biotechnologies LTD, Cardiff, Wales). Dust samples were analyzed using an ELISA test to quantify Derp1 and Der f1 mite allergens. For data analysis, two logistic random-intercept models were used. The level of significance considered was α= 0.05.
RESULTS AND DISCUSSION: We collected 100 samples of EBC in preschool-age children, with a mean age of 5.0±0.6 years. 57% of the subjects were male. Schoolroom average occupancy was 19.73±3.97 children. EBC NO3- mean values were 4.42±1.60 μmol and VOCs median values were 200 μg/m3 (P25-P75: 82-436 μg/m3). When analyzing the association between IAQ parameters and airway inflammation, it was only found an association between VOCs and NO3-: regression coefficient (ˆb) = 0.32(CI95%: 0.11 to 0.53; p=0.003). No significant association between PM10, house dust mites, fungi, bacteria, temperature and relative humidity was found. EBC pH had no association with any of the main IAQ parameters analysed. The relationship between EBC analyses can be a useful non-invasive and easy-to-collect technique for airway inflammation monitoring if proper parameters are defined. Different studies showed that nitrogen products and in EBC were associated with asthma and FEV1deterioration.
CONCLUSION: At this study, VOC were the only IAQ parameter significantly associated with EBC airway inflammation biomarkers, namely nitrates. VOCs monitoring may constitute a parameter to consider in order to minimize the impact of IAQ in airway inflammation of preschool-age children.
Palavras Chave: children; air pollution, indoor