Exposure to NO₂ in children's parks during a high pollution episode based on mesoscale simulations

Air pollution is one of the greatest environmental risk factors for Human health, especially worrying in urban areas, where children are one of the most vulnerable sectors. Continuous information of exposure to different air pollutants is therefore needed, especially in areas where children spend most of their time, such as urban parks. In this study, we use 500 m horizontal resolution mesoscale simulations to assess children's exposure to NO₂ during a high pollution episode in five urban parks across Vitoria-Gasteiz. Children living at a maximum 5-min walking time from each park are considered for exposure calculation. Results show that four parks exceed current hourly limit values, and all of them exceed the daily limits defined by the World Health Organization 2021 guideline. The use of hourly values instead of the daily mean for pollutant exposure calculation shows that the latter underestimates morning exposure and overestimates evening exposure. This result highlights the need for high time resolution to achieve better exposure assessment. The spatial resolution used in this study also shows the capacity to differentiate between parks, improving the exposure estimates with respect to the use of official air quality stations. This methodology provides continuous information to assess short-term exposure, especially important in a high pollution episode, and allows for pollution gaps filling for long-term exposure studies.