A new study in mice, published in Science Immunology, challenges the so-called 'hygiene hypothesis', the idea that a contributing factor to allergies is that there is an under-stimulated immune system that has not seen enough exposure to germs from current hygienic conditions. In the research, laboratory mice still developed allergies when exposed to various microbes.

The State Meteorological Agency (AEMET) has issued an information note warning of "exceptionally high" temperatures for this time of year in Spain, especially between Friday 29 September and Monday 2 October.

Chronic exposure to various air pollutants has been linked to an increased risk of stroke, but the short-term effects have been less well studied. A review of 110 papers and more than 18 million stroke cases shows that recent exposure - in the five days prior to stroke - also increases the likelihood of stroke. The results are published in the journal Neurology.

An analysis published in BMJ Evidence-Based Medicine reviews epidemiological research on persistent covid and concludes that many studies overestimate its prevalence due to overly loose definitions, absent or inadequate control groups and other methodological shortcomings.

Training people to get rid of unwanted thoughts can improve their mental health, according to a study from the University of Cambridge (UK). The research team stresses that these results "challenge the century-old wisdom" that trying to get rid of negative thoughts can have harmful effects on mental health. The study, published in Science Advances, involved 120 adults - some with major depression, anxiety and post-traumatic stress disorder - from 16 countries, who underwent a three-day online training to suppress certain thoughts. After the training, participants reported feeling less anxiety, negative emotions and symptoms of depression.

Since the first case of epizootic haemorrhagic disease (EHD) in Spain was detected in cattle in November 2022, it has spread among farms in several autonomous communities in dozens of outbreaks. The mosquito-borne disease does not affect humans, but has the potential to cause economic losses.

Las lluvias torrenciales caídas en Libia hace dos semanas fueron 50 veces más probables por el calentamiento global provocado por la acción humana. Algo similar ocurría con las lluvias caídas en Grecia, Bulgaria y Turquía, que fueron 10 veces más probables por el cambio climático, según concluye un estudio de atribución rápido de la Word Weather Attribution (WWA). La investigación apunta a que la tragedia en Libia se agravó por otros factores humanos, como construcciones en llanuras inundables y presas en mal estado. Los autores también analizaron las inundaciones registradas en España a principios de septiembre y concluyeron que precipitaciones tan intensas se esperan una vez cada 40 años. 

Research published in PNAS has analysed the conservation status of 5,400 terrestrial vertebrate genera, comprising 34,600 species, between the years 1500 and 2022. The authors found that 73 genera have become extinct since 1500. Birds suffered the greatest losses, with 44 extinct genera, followed by mammals, amphibians and reptiles. The results reveal that the extinction rate was 35 times higher during this period than the average extinction rate over the previous million years. According to the researchers, the genera lost in the last five centuries would have taken 18,000 years to become extinct without human impact.

A study conducted with nearly 58,000 boys and girls revealed that increased television or DVD screen time starting from 12 months of age had a negative impact on later development, as reported by JAMA Pediatrics.

Most research has studied marine heatwaves at the sea surface. Now, a study published in Nature Climate Change analyses the effects of these phenomena at depths of up to 2,000 metres. The research, based on data from waves occurring between 1993 and 2019, shows that these waves tend to be more intense between 50 and 200 metres, and that their duration increases up to twice as much with depth compared to the surface, which has an impact on the marine fauna living in that area.