PracticeUpdate Conference Series: ERS 2018

The researchers calculated average annual exposure to three air pollutants: two sizes of fine particulate matter (PM2.5 and PM10) and nitrogen dioxide (NO 2 ) from birth until age 18 years. PM2.5 and PM10 are atmospheric, particulate matter of diameter <2.5 and 10 µM, respectively. PM2.5 is approximately 3% of the diameter of a human hair. Sources of PM2.5 include power plants, motor vehicles (internal combustion engines), airplanes, residential wood burning, forest fires, agricultural burning, volcanic eruptions, and dust storms. Sources of PM10 include dust, emissions from industry, vehicle emis- sions, and rubber tire abrasions. Sources of NO 2 include internal combustion engines and burning fossil fuels such as coal. The investigators also calculated annual average exposure to greenness in a 100-m zone near the home for the same period; greenness was assessed by means of the Normalised Difference Vegetation Index (NDVI), which uses satellite images to quantify vegetation in an area. A total of 608 participants (12%) suffered from more than three respira- tory symptoms; 384 (7.7%) severe wheeze; and 444 (9.4%), late-onset asthma. Examples of findings from contributing centers showed that, in Bergen, exposure to PM2.5 and NO 2 increased the probability of late-onset asthma by 6–22%. Exposure to PM10 increased the probability of devel- oping respiratory symptoms by 21% in Uppsala and by 23% in Bergen. Exposure to greenness before age 10 years was associated with a 71% lower probability of wheeze in Tartu. Exposure to greenness between the ages of 11 and 18 years was associated with a 29% lower probability of respiratory symptoms and 39% lower probability of wheeze in Tartu. Until now, little has been known about the association between expo- sure to air pollution as a child and long-term respiratory problems in adulthood.

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environment so it’s important that we continue to monitor their levels and try to learn more about their effects.” She continued, “Babies and children are the most susceptible population since their organs are still under development, and damage to the lungs at birth can have a huge impact in later life. A clear link has been demonstrated between low lung function in early adulthood and respira- tory, cardiovascular, and metabolic issues in later life, and ultimately, in premature death. “There are other chemicals present in the environment, such as phthalates and phenols, for example, that may also have the potential to interfere with children’s developing lungs. Studies on these individual compounds and assessing combinations of chemicals are needed to understand their effects on childhood respiratory and overall health,” Dr. Gaga said.

Dr. Casas Sanahuja and colleagues studied 1308 babies born in the Valencia, Gipuzkoa, and Sabadell regions of Spain between 2004 and 2008. They measured levels of seven different organochlorine compounds in the pregnant mother’s bloodstream or umbilical cord blood. As the children grew, their lung function was measured at ages 4 and 7 years. Spirometry was performed as well as an examination for signs of airway obstruction. Levels of DDE, formed when DDT breaks down, were linked with poorer lung function at both 4 and 7 years of age. For example, exposure to maternal con- centrations of DDE between 0.23 and 0.50 ng/mL was associated with a 50-mL reduction in forced expiratory volume in 1 second. Average (median) level of DDE was 0.28 ng/mL. Dr. Casas Sanahuja stressed, “A reduction this size in the amount of air a child can exhale would not be considered clinically relevant for a healthy child, but these

small changes are highly relevant at the population level and can be important in children with respiratory conditions.” Dr. Casas Sanahuja explained that organo- chlorine compounds include the pesticide DDT, as well as electrical insulators and other industrial products. Though banned in most of the world, these chemicals degrade very slowly and remain present in the environment and in food. Research has suggested links between exposure to these chemicals in the uterus and reports of childhood respiratory dis- eases such as wheezing, asthma, and chest infections. The researchers hope to study the impact of exposure to organochlorine com- pounds in the uterus on older children and teenagers to determine whether this effect persists long term. Mina Gaga, MD, of Athens Chest Hospital in Greece, who was not involved in the study, commented, “We know organ- ochlorine compounds are still in our

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ERS 2018 • PRACTICEUPDATE CONFERENCE SERIES 13