Impact of school indoor air quality on children's respiratory health in Maltese primary schools

Abstract

The International Study of Asthma and Allergies in Childhood (ISAAC) Malta study has shown an increase in the prevalence of wheezing in most geographical regions of the Maltese islands. The importance of school indoor air quality (SIAQ) has been recognised since children spend most of their time outside home within the school environment. The most common organic pollutants within the school indoor environment are cat (Fel d 1), dog (Can f 1), dust mite (Der f 1, Der pI), cockroach (Bla gland 2), mould allergens and bacteria. The most commonly identified pollutants include CO2 , CO, volatile organic compounds (VOC), formaldehyde, 0 3 , N02 ,and particulate matter (PM 10, PM 2.5). To date there is no data regarding the impact of school indoor air quality on the children's health in Malta. Five primary state schools were selected randomly throughout the Maltese Islands. The cumulative prevalence of wheezing (32.98%), current wheezing (17.8%) and diagnosed asthma (16.75%) among the study population were in keeping with previously reported ISAAC Malta data and was higher than the mean SINPHONIE prevalences. Schools 4 (B'Bugia) and 5 (Fgura) located in the southern part of the island had the highest prevalence of cumulative and current wheezing. Up to 34.03% of the children complained of rhinitic symptoms 'ever' while 29.84 % complained of rhinitis symptoms during the previous 12 months. Indoor formaldehyde, carhon monoxide and particulate matter (PM 2.5; PM 10) levels exceeded the recommended WHO air quality thresholds. Outdoor ozone and particulate matter (PM 2.5 and PM 10) concentrations were higher than the limits recommended by WHO. Microbiolgical contaminants have never been studied in local schools. PenAsp microorganisms had the highest mean concentration within local schools followed by the Mycobacterial and Streptomyces species. Both cat and dog allergens were detected within the school indoor environment with a significant positive correlation seen between cat allergen levels and the number of children owning a cat. Schools located in the southern part of the island were associated with an increased prevalence of wheezing (OR 3.77, p=O.012) and rhinoconjunctivitis (OR 3.59; p=O.003). Classrooms with small openable window areas had an increased prevalence of both nocturnal dry cough (OR 1.38; p=O.001) and rhinitic symptoms which had a negative impact on the child's daily activities (OR 3.14; p=O.016). The various school building, classroom, maintenance, cleaning and the outdoor school environment characteristics were directly associated with an increased risk of high exposure to indoor chemical and biological pollutants in this study. High exposure to indoor chemical and microbiological pollutants and allergens were significantly associated with both upper and lower airway disease. Atopy was also significantly associated with deranged indoor physical parameters. Proposals for an ideal school have been submitted. Most importantly the school should be located far away from any industrial, power generating facilities, fuel depots and main roads characterized by heavy traffic. Specific areas needing urgent attention are ozone, NOz , particulate matter (PM 2.5 and PM 10) and VOC's. Perchlorate usage should be more tightly regulated and more research is needed in this field. Classrooms should have adequate ventilation with large areas of windows that are openable. The dependence of schools in Malta on natural ventilation emphasizes the need for policies to improve outdoor air quality. Standardized cleaning protocols including the use of HEPA equipped vacuum cleaners are needed to regularly remove dust from flat surfaces in classrooms. Schools and classrooms should be regularly maintained and refurbished. Awareness programs should be established so as to educate school staff in the prevention and management of respiratory allergic disease especially asthma. More research is needed to identify which irritants are associated with allergic disease.