Studies using fixed site monitoring data
Studies using fixed-site monitoring data rather than personal monitoring data are subject to misclassification of the exposure because fixed site monitors do not account for individual mobility that affect exposure. Although, this typically results in non-differential exposure misclassification that underestimates the risk of air pollution. Additionally, fixed-site monitors average the exposure of air pollution in a region, thereby not accounting for the geospatial variation of air pollution levels in a region. Future studies could incorporate land use regression models to assess the interaction of spatial differences of air pollution across a city along with acute temporal variation. Misclassification of the cases is also an important consideration. The study used International Classification Disease (ICD-9) codes to identify patients presenting to the emergency department with upper gastrointestinal bleeding secondary to orexin receptor disease. All studies relying on administrative databases unfortunately include false-positive cases and miss true cases. Furthermore, in case crossover studies, cases serve as their own controls. Because within-individual comparisons are being made, confounding from time-independent risk factors (eg, colonization by ) are controlled for by the design of the study. However, residual confounding might occur with time-dependent factors such as NSAIDs, whose use might vary day by day. Air pollution studies can also be limited by multiple comparison errors because associations are explored with multiple pollutants and across several exposure time periods. Consequently, the probability of observing statistically significant findings by chance alone is increased. Tian and colleagues attempted to account for chance findings by including positive control cohorts of respiratory and circulatory diseases that are well known to be affected by acute elevation in air pollution exposures. Nonetheless, replication studies are necessary in other cities in Asia with similar levels of air pollution.
Tian and colleagues\' Article suggests that upper gastrointestinal bleeding secondary to peptic ulcer disease might be triggered by exposure to high levels of NO in elderly patients living in Hong Kong. If these findings are corroborated in the future, then the association between air pollution and peptic ulcer disease would add to a growing body of scientific literature suggesting that air pollution can harm the gastrointestinal tract. Moreover, air pollution is a modifiable and avoidable risk factor. If air pollution promotes the onset of upper gastrointestinal bleeding secondary to peptic ulcer disease, then policies to reduce emissions could be preventive policies. Additionally, clinicians can warn elderly patients at risk of peptic ulcer disease to avoid outdoor exposures on days of high NO levels.
Ecosystems worldwide are threatened by climate change and a massive reduction in biodiversity. The main causes are human emissions of greenhouse gases, agriculture, deforestation, and overfishing, all of which are often driven by food production. Because human life depends on the stability of the earth\'s ecosystems, the destabilisation of planetary health represents the greatest challenge of our time, and the future of our species will depend on the actions we take. Physicians around the world counsel millions of patients every day and enjoy societies\' recognition and trust. These attributes offer physicians large personal and political influence; as such, physicians should become aware of their potentially healing role, not only for patients\' health, but also for planetary health. In promoting healthy lifestyles, physicians should consider that animal products are not only an independent risk factor for cardiovascular disease and cancer, but also that their production causes 25% of global greenhouse gas emissions and harms biodiversity due to its large land requirements. Therefore, physicians should use their societal influence for the common good and advocate for healthy lifestyles and healthy public policies aligning efforts of medicine, public health, and planetary health. In moving towards a locally produced, biologically grown, plant-based diet, everyone can participate in promoting planetary ecosystem stability and global health.