Background: Indoor air quality (IAQ) in classrooms affects children's health and academic performance. The aim of this pilot study was to determine IAQ in elementary schools different in their internal and external characteristics, in settings of COVID-19 epidemics. Methods: IAQ parameters: fine particulate matter (PM 2,5 ) mass concentration, CO 2 concentration, temperature and relative humidity were measured in parallel in four elementary schools/classrooms during October (non-heating season) and four months (including holiday in January) of heating season. IAQ parameters were measured in settings of anti-epidemic restrictions (≤13 students in classroom, frequent ventilation). Results: During October, except in one school, PM 2,5 concentrations were below the upper recommended value (25μg/m³), but started rising in all schools in the heating season. The highest concentrations of PM 2,5 were registered in two schools with closed or shortly opened windows. CO 2 concentrations were mostly in the recommended range (up to 1000ppm) except in the school with constantly closed windows and in three schools in February when concentrations were higher. Except in one, the same school, and in January, both temperature and relative humidity were out of the recommended range (24,0-27,0°C in non-heating; 20,0-24,0°C in heating season; and 45-55%), with temperature mainly above and relative humidity mainly below it in three schools. The largest deviation in temperature and relative humidity were registered in urban schools. Registered differences may be explained by different internal and external characteristics.

ObjectivesTo evaluate the sleep patterns among young West Balkan adults during the third wave of the COVID-19 pandemic.Design and settingCross-sectional study conducted using an anonymous online questionnaire based on established sleep questionnaires Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI) (February–August 2021).ParticipantsYoung adults of Bosnia and Herzegovina, Croatia and Serbia.ResultsOf 1058 subjects, mean age was 28.19±9.29 years; majority were women (81.4%) and students (61.9%). Compared with before the pandemic, 528 subjects (49.9%) reported a change in sleeping patterns during the pandemic, with 47.3% subjects reporting sleeping less. Mean sleeping duration during the COVID-19 pandemic was 7.71±2.14 hours with median sleep latency of 20 (10.0–30.0) min. Only 91 (8.6%) subjects reported consuming sleeping medications. Of all, 574 (54.2%) subjects had ISI score >7, with majority (71.2%) having subthreshold insomnia, and 618 (58.4%) PSQI score ≥5, thus indicating poor sleep quality. Of 656 (62.0%) tested subjects, 464 (43.9%) were COVID-19 positive (both symptomatic and asymptomatic) who were 48.8%, next to women (70%), more likely to have insomnia symptoms; and 66.9% were more likely to have poor sleep quality. Subjects using sleep medication were 44 times, and subjects being positive to ISI 15.36 times more likely to have poor sleep quality. In contrast, being a student was a negative independent predictor for both insomnia symptoms and poor sleep quality, and mental labour and not working were negative independent predictors for insomnia symptoms.ConclusionsDuring the third wave of the pandemic, sleep patterns were impaired in about half of young West Balkan adults, with COVID-19-positive subjects and being women as positive independent predictors and being a student as negative independent predictor of impaired sleep pattern. Due to its importance in long-term health outcomes, sleep quality in young adults, especially COVID-19-positive ones, should be thoroughly assessed.