New York, April 20 : Exposure to ultrafine particles during pregnancy enhances the risk for respiratory viral infection, shows a study. During pregnancy, women are more susceptible to severe respiratory infections from multiple viruses, including influenza A virus (IAV), respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus (SARS-CoV-2). In addition, pregnant women are disproportionately affected by influenza, resulting in a more than 10-fold increase in hospitalisation risk. "We know that air pollution affects the pulmonary immune system, making individuals more susceptible to viral infections," said Dr. Natalie Johnson, associate professor in the Texas A&M University School of Public Health. In the study, published in the journal Particle and Fibre Toxicology, the team pointed out that there are several physiological characteristics that explain maternal susceptibility to viral infection. Among those are increased cardiac output and decreased tidal volume - the amount of air that moves in or out of the lungs with each respiratory cycle - as well as immunological changes such as selective modulation of immune cell subsets to protect the developing foetus. The researchers also highlighted that vaccination compliance during pregnancy is generally below 50 per cent, despite vaccination against influenza being safe and effective, leading to increased risk for developing respiratory infection. As a result, air pollution, which is a worldwide environmental health issue, is responsible for one in nine deaths with an annual premature mortality of more than 7 million. A mixture of gases and tiny airborne particulate matter, which is categorised as UFPs, are critical to recognise and identify, especially to protect vulnerable populations. The team said these findings support future clinical and regulatory interventions for protecting pregnant women and controlling UFPs. AIt is imperative that pregnant women in urban cities, where influenza and UFPs are more prevalent, are provided vaccinations and preventive measures limiting UFP exposure to protect maternal health, they noted. "Air pollution is a pervasive environmental health issue," Johnson said. "Strategies to protect the most vulnerable, like pregnant women, are of high priority to decrease adverse health effects." /IANS