Identification of Regions with High Ozone Concentrations Aiming the Impact Assessment on Childhood Asthma

ABSTRACT

High concentrations of near-surface ozone are known to have negative impacts on human health, especially among risk groups such as persons with respiratory problems, children, and the elderly. The aim of this work was to identify regions with high ozone concentrations and very low concentrations of other pollutants, where further studies will be performed regarding the specific impact of ozone on childhood asthma. For that, the concentrations of ozone and of its precursors at remote areas were assessed and compared with those observed at an urban area influenced by traffic. Measurements using passive samplers were compared with those performed with continuous monitors and it was possible to conclude that measurements with passive samplers had satisfactory reproducibility and precision. For O₃, the comparison of both methods showed a maximum absolute difference of +4.10 μ g.m⁻³ and relative differences lower than −8.8%. The maximum absolute difference for NO₂ was +5.2 μ g.m⁻³ and the relative differences were greater than 12% only for very low concentrations (2–3 μ g.m⁻³). Comparing with one urban site, the results obtained at remote sites showed significantly lower concentrations of nitrogen dioxide (12 to 20 times) and volatile organic compounds (2 to 8 times) and greater ozone concentrations (2 to 3 times). It was inferred that the lower concentrations of nitrogen dioxide were the main reason for the greater ozone concentrations found at the remote sites. The remote areas studied showed very high ozone concentrations and very low concentrations of other pollutants, being an adequate zone to perform further studies regarding the specific impact of ozone on childhood asthma without the confounding effects of other pollutants.

Key Words:

• ozone
• remote areas
• urban area
• passive sampling
• continuous monitoring

ACKNOWLEDGEMENT

Authors are grateful to Comissão de Coordenação e Desenvolvimento Regional do Norte for kindly providing the air quality and meteorological data. The authors also thank Fundação Calouste Gulbenkian.