When fires break out, atmospheric concentrations of ozone and particulate matter (PM) rise. Depending on the intensity of the flames and the wind, this column of smoke can travel tens or even hundreds of kilometres, exposing the population to these harmful substances. A study led by the Carlos III Health Institute, using data from nine Spanish provinces, shows that on days when fires were burning, there was a higher number of A&E admissions due to respiratory problems.
“The key finding we observed was that, on days when biomass burning occurred, ozone was responsible for more than twice as many hospital admissions as particulate matter itself,” explained Cristina Linares, a research scientist and co-director of the Reference Unit on Climate Change, Health and the Urban Environment at the Carlos III Health Institute (ISCIII), at a briefing organised by SMC Spain.
The research, published in Science of the Total Environment last year, analyses data from 2013 to 2018 for Madrid, the Balearic Islands, Las Palmas, Málaga, A Coruña, Seville, Valencia, Vizcaya and Zaragoza, as provinces representative of Spain’s geography. Data on particulate matter and other harmful compounds generated by wildfires were provided by CIEMAT, whilst data on A&E admissions came from the National Institute of Statistics.
The study shows that admissions attributable to ozone due to respiratory problems rose from 8.3 per cent on days without fires to 21 per cent on days when fires were burning, whilst those attributable to PM10 rose from 0.8 per cent on days without fires to 13.9 per cent on days with fires.
“When ozone levels rise by a certain proportion, admissions also increase by a specific amount; this is what is known as an attributable risk. That is what we can conclude from this study, but we can never establish causality,” explained Julio Díaz, research professor and co-director of the Reference Unit on Climate Change, Health and the Urban Environment at the ISCIII.
The researchers plan to update this time series and its impact on health to measure the impact of large-scale wildfires, particularly from 2022 onwards, when the number of hectares being burnt is highest and the fires are most intense. “The next time series will likely cover the period from 2021 to 2025 or 2026,” Linares revealed.
Monitoring and surveillance plans to protect public health
During the briefing, Díaz and Linares referred to the warnings issued by both the Ministry of Health and the regional governments regarding the smoke laden with particulates and harmful compounds from the recent fires in Ávila and Madrid, as well as the one in La Vall d’Uixó. The authorities advised the public to close doors and windows and not to go outside.
“It shouldn’t just be a case of saying ‘stay indoors, don’t go out, don’t take part in outdoor activities’; rather, the authorities should ensure that background air pollution is reduced,” the researcher argued. Linares pointed out that, even without wildfires, during events such as heatwaves, there should already be traffic restrictions in cities, because high temperatures cause pollutants to have a more severe impact on people’s health.
Incidents of this kind serve to highlight the air quality monitoring systems in place in cities and to encourage the public to routinely check this data, which affects their health, just as they would check weather forecasts; however, according to the authors, we need to go further.
“When a fire breaks out, we should know specifically what types of pollutants are present, how many days it lasts, and how many towns and cities have been affected by that plume…”, suggested Linares.
Díaz emphasised the need to develop surveillance plans to monitor this data. “Just as the MoMo system, which monitors mortality, automatically records deaths occurring within two days, a very important step would be to see if we can move from theory—that is, our theoretical studies—to practice, in other words, to determine whether this is actually happening,” he stressed.
As an example of the usefulness of this type of study, Díaz spoke of an initiative they are carrying out with La Paz University Hospital (Madrid), where they are developing a model to predict emergency admissions for various causes—such as respiratory, circulatory and neurological conditions—based on environmental indicators. “Once this model is up and running, if ozone concentrations have risen today from 20 micrograms to 40 micrograms, the prediction tool will tell us that tomorrow, instead of 20 admissions, there will be 27 admissions due to respiratory problems,” he concluded.
