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Health indicators for exposure to increased ozone concentrations

Issue 26-05-2014VITO recently conducted a study on behalf of MIRA on the health impact of ozone. The study yielded two indicators for monitoring the health impact of ozone in Flanders. Firstly, the existing MIRA indicator was updated. This indicator describes lung function reduction at increased ozone concentrations and is relevant for the 5-to-55 age group. Secondly, a new indicator was developed that applies to older persons (>65 years). The indicator describes the number of extra hospitalisations due to increased ozone exposure.

Updating of the indicator for lung function reduction in the 5-to-55 age group

Exposure to excessive ozone concentrations may cause health problems such as long function reduction. A measure of the lung function is the volume of air that can be forcibly exhaled in one second (FEV1 or Forced Expiratory Volume in 1 second). By exposing subjects to different ozone concentrations, it becomes possible to establish an experimental relationship between concentration (dose) and lung function reduction (health effect or response). The effect of lung function reduction at increased ozone concentrations is mainly observed in the 5-to-55 age group.

MIRA already reports annually on the health impact of ozone, based on the FEV1 reduction. The basis of this indicator was retained, but updated. The underlying dose-response relationships were updated based on new scientific evidence. Furthermore, the indicator is now expressed as the average lung function reduction that minimally occurs during the 18 days of the year (i.e. 5 % of 365) with the highest ozone concentrations. This clearly illustrates the effect of peak ozone concentrations.

New indicator based on hospitalisations among 65+

Above 55 years, the lung function decreases minimally at increased ozone concentrations. This is why a new indicator was developed that is actually relevant for older persons (>65 years).

This indicator shows the extra number of emergency hospitalisations for respiratory disorders at increased ozone concentrations. Unlike the FEV1 indicator, the hospitalisation indicator is based not on experiments, but on epidemiological studies in which statistical relationships are sought between extra hospitalisations and ozone concentrations.

The FEV1 indicator shows primarily the effect of exposure to peak ozone concentrations for a number of days per year. The hospitalisation indicator mainly reflects increased ozone concentrations throughout the year, as it is based on ozone exceedances above 70 µg/m³.

MIRA will annually follow up both health indicators.

Read the English summary of the Dutch report ‘Health indicator for exposure to increased ozone concentrations’

Study commissioned by MIRA, the Environment Reporting Unit
Research report MIRA/2013/13 - VITO/2014/MRG/49

researchers: Jurgen Buekers, Luc Int Panis, VITO

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