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Time Series Analysis of Asthma Hospital Admissions and Air Quality in Sofia – A Pilot Study

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Environmental Protection and Disaster Risks (EnviroRISKs 2022)


Asthma is a multifaceted inflammatory disease of the airways, which takes a heavy toll on public health and quality of life in Bulgaria. The present study aimed to investigate the short-term effects of air pollution on hospital admission for asthma in the city of Sofia.

Daily admission counts and air pollutant concentrations (PM2.5, PM10, NO2, SO2, CO, and O3) were obtained for Sofia in the period January 1, 2009 to December 31, 2018. Their associations were analyzed using negative binomial regressions with air pollution lagged over 0–7 days.

In the child population, at some lags, 10 µg/m3 increase in NO2 increased the risk of hospital admission by up to 6%, SO2 by 13%, and PM2.5 by 3%. Results for O3 were conflicting, even though at some lags the risk reached 5% per 10 µg/m3. At lag0, CO increased the risk of hospitalization in the group 0–4 years by 7.4%, which reached an IRR of 2.53 (95% CI: 1.27, 5.07) in the distributed lag models. It was estimated that approximately 6% of the admissions in children (5–14 years old) could be attributable to short-term PM2.5 ≥ 15 µg/m3 and NO2 ≥ 25 µg/m3.

Overall, short-term increases in some air pollutants in Sofia increased the risk of hospital admissions, more clearly among asthmatic children, over the following week. A small but non-trivial proportion of admissions in 5–14 years old children was attributable to air pollution.

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  1. Milushewa, P., Doneva, M., Petrova, G.: Availability and reimbursement of biological products for severe asthma in Bulgaria. SAGE Open Med. 8, 2050312120951067 (2020)

    Article  Google Scholar 

  2. Health Effects Institute (HEI).: State of Global Air 2020. Special Report. Health Effects Institute, Boston, MA (2020)

    Google Scholar 

  3. Pfeffer, P.E., Mudway, I.S., Grigg, J.: Air pollution and asthma: mechanisms of harm and considerations for clinical interventions. Chest 159(4), 1346–1355 (2021)

    Article  CAS  Google Scholar 

  4. Tiotiu, A.I., et al.: Impact of air pollution on asthma outcomes. Int. J. Environ. Res. Public Health 17(17), 6212 (2020)

    Article  CAS  Google Scholar 

  5. Bontinck, A., Maes, T., Joos, G.: Asthma and air pollution: recent insights in pathogenesis and clinical implications. Curr. Opin. Pulm. Med. 26(1), 10–19 (2020)

    Article  CAS  Google Scholar 

  6. Huang, J., et al.: Outdoor air pollution and the risk of asthma exacerbations in single lag0 and lag1 exposure patterns: a systematic review and meta-analysis. J. Asthma (2021).

  7. Simidchiev, A., Ljubomirova, C., Vodenicharova, A., Kundurzhiev, T., Tzacheva, N.: Link between fine particulate matter in ambient air and health-related contacts in Sofia’s ambulance, outpatient and hospital emergency services. Eur. Respir. J. 56, 1300 (2020)

    Google Scholar 

  8. Krachunov, I.I., et al.: Impact of air pollution and outdoor temperature on the rate of chronic obstructive pulmonary disease exacerbations. Folia Med. (Plovdiv) 59(4), 423–429 (2017)

    Article  CAS  Google Scholar 

  9. Doneva, M., et al.: Chronic obstructive pulmonary disease exacerbations and progression in relation to ambient air pollutants exposure. J. Thorac. Dis. 11(6), 2490–2497 (2019)

    Article  Google Scholar 

  10. World health organization. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. World Health Organization. License: CC BY-NC-SA 3.0 IGO (2021). Accessed 15 May 2022

  11. Kindzierski, W., Young, S., Meyer, T., Dunn, J.: Evaluation of a meta-analysis of ambient air quality as a risk factor for asthma exacerbation. J. Respir. 1(3), 173–196 (2021)

    Article  Google Scholar 

  12. Newson, R.B.: Attributable and unattributable risks and fractions and other scenario comparisons. Stand. Genomic Sci. 13(4), 672–698 (2013)

    Google Scholar 

  13. Orellano, P., Quaranta, N., Reynoso, J., Balbi, B., Vasquez, J.: Effect of outdoor air pollution on asthma exacerbations in children and adults: Systematic review and multilevel meta-analysis. PLoS ONE 12(3), e0174050 (2017)

    Article  Google Scholar 

  14. Khomenko, S., et al.: Health impacts of the new WHO air quality guidelines in European cities. Lancet Planetary Health 5(11), e764 (2021)

    Article  Google Scholar 

  15. Zheng, X.Y., et al.: Association between air pollutants and asthma emergency room visits and hospital admissions in time series studies: a systematic review and meta-analysis. PLoS ONE 10(9), e0138146 (2015)

    Article  Google Scholar 

  16. Air pollution and child health: prescribing clean air. Summary. Geneva: World Health Organization, (WHO/CED/PHE/18.01). Licence: CC BY-NC-SA 3.0 IGO (2018)

    Google Scholar 

  17. Sedghy, F., Varastehl, A.R., Sankian, M., Moghadam, M.: Interaction between air pollutants and pollen grains: the role on the rising trend in allergy. Rep. Biochemi. Mol. Biol. 6(2), 219–224 (2018)

    CAS  Google Scholar 

  18. Lam, H.C.Y., Jarvis, D., Fuertes, E.: Interactive effects of allergens and air pollution on respiratory health: a systematic review. Sci. Total Environ. 757, 143924 (2021)

    Article  CAS  Google Scholar 

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This work has been carried out in the framework of the National Science Program “Environmental Protection and Reduction of Risks of Adverse Events and Natural Disasters”, approved by the Resolution of the Council of Ministers №577/17.08.2018 and supported by the Ministry of Education and Science (MES) of Bulgaria (Agreement № Д01-279/03.12.2021).

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Correspondence to Angel M. Dzhambov .

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Dzhambov, A.M., Dikova, K., Georgieva, T., Mukhtarov, P., Dimitrova, R. (2023). Time Series Analysis of Asthma Hospital Admissions and Air Quality in Sofia – A Pilot Study. In: Dobrinkova, N., Nikolov, O. (eds) Environmental Protection and Disaster Risks. EnviroRISKs 2022. Lecture Notes in Networks and Systems, vol 638. Springer, Cham.

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