Global Alliance against Chronic Respiratory Diseases Symposium on Air Pollution: Overview and Highlights
Air pollution is a global issue that significantly impacts human health and the environment. The Global Alliance against Chronic Respiratory Diseases (GARD), an alliance of the World Health Organization (WHO), held a one-day symposium on October 25, 2019, in Beijing, China, to discuss the effects of air pollution on health. This symposium brought together 19 experts from around the world to present various aspects of air pollution, its mechanisms, and potential interventions. The discussions highlighted the urgent need for political and public action to reduce air pollution at its source, as it is closely linked to global warming and harms multiple body systems even at levels below international standards.
Health Impact of Air Pollution in Europe
Giovanni Viegi presented data on the health impact of air pollution in Europe. Despite improvements in air quality, pollution levels in Europe still exceed WHO guidelines. The European Environmental Agency’s 2019 report revealed that in 2017, WHO guidelines for particulate matter (PM) were exceeded in 51% of reporting stations across all countries except Finland, Estonia, and Ireland. Ozone (O3) levels exceeded WHO guidelines in 95% of reporting stations, and nitrogen dioxide (NO2) levels were above the guideline in 10% of stations. PM2.5 levels were highest in Northern Italy and Poland, with hotspots in Greece, Turkey, and Romania. Air pollution in Europe was associated with over 400,000 premature deaths in 2016, primarily due to PM2.5, NO2, and O3. Even levels below WHO standards were linked to excess deaths, emphasizing the need for stricter air quality measures.
Impact of Air Pollution on Asthma and Rhinitis
Jean Bousquet discussed the overwhelming evidence linking air pollution to increased incidence and exacerbations of asthma and rhinitis. A significant portion of childhood asthma cases is attributable to outdoor air pollution, and meeting WHO air quality recommendations for NO2, PM2.5, and black carbon could prevent 23%, 33%, and 15% of incident asthma cases, respectively. Allergens and air pollution have synergistic effects, with O3 having a greater impact during the grass season. The POLLAR project, which monitors atmospheric pollutants and pollens, has shown that air quality alerts reduce the use of asthma medications.
Air Pollution and Exacerbations of Chronic Obstructive Pulmonary Disease
Pi-Xin Ran highlighted the association between air pollution and chronic obstructive pulmonary disease (COPD). Pollutants such as sulfur dioxide (SO2), NO2, PM10, PM2.5, and O3 increase the risk of hospitalization for COPD patients. Improved air quality in Guangdong Province between 2013 and 2017 showed that reductions in PM2.5, PM10, and O3 benefited COPD patients the most. Both indoor and outdoor air quality affect COPD exacerbations, with PM10, PM2.5, and O3 having the greatest impact.
Air Pollution, Climate Change, and Allergic Respiratory Diseases
Cun-Rui Huang explained how climate change and air pollution worsen asthma and allergic lung diseases. Warmer temperatures increase O3, NO2, PM, heat waves, dust storms, and wildfires. Climate change also leads to the migration of plants, animals, and humans, exposing people to new allergens. Thunderstorms can concentrate fine-particle pollens and trigger asthma attacks. Temperature variations within the same day and on neighboring days increase asthma exacerbations. Flooding promotes mold growth, which is associated with asthma.
Air Pollution Mechanisms, Systemic Effects, and Benefits of Its Reduction
Dean Schraufnagel discussed the mechanisms by which air pollution harms health. Systemic inflammation is the most well-studied mechanism, with pollutants inducing an inflammatory response in the lungs that spreads to other organs. Particle size determines where inflammation occurs, with PM2.5 and ultrafine particles (PM0.1) reaching the alveoli. PM0.1 can cross cellular membranes and translocate to most cells in the body, including the brain. Reducing pollution at its source leads to prompt benefits, such as halving asthma medical visits and reducing cardiovascular mortality during the Beijing and Atlanta Olympics. National and supranational programs that reduce air pollution have saved hundreds of thousands of lives and trillions of dollars.
Environmental Pollution and Altered Lung Function
Wei-Hong Chen presented cohort studies from Wuhan and Zhuhai, showing that high PM2.5 levels are associated with spirometric lung function decline. Short-term exposure to PM2.5 was linked to a drop in forced vital capacity and forced expiratory volume in 1 second (FEV1), while long-term exposure showed a greater decline in FEV1/forced vital capacity. Polycyclic aromatic hydrocarbon (PAH) metabolite levels were associated with decreased lung function, with more pronounced effects in smokers. PM2.5-bound PAHs reduced lung function through oxidative damage and inflammatory response.
Short-term Cardiopulmonary Effects of Indoor PM in Patients with COPD
Fu-Rong Deng emphasized the importance of indoor air quality, as people spend over 80% of their time indoors. Indoor-originating PM2.5 was more strongly associated with decreased cardiopulmonary function in COPD patients than outdoor-originating PM2.5. Higher body mass index had an additive effect with air pollution in decreasing heart rate variability and increasing cardiovascular risk. Smaller-size PM had larger effects on the heart and lungs, and oxidative stress caused by air pollution altered seven urinary markers.
Taurine Ameliorates PM0.1-Induced Emphysema by Affecting Mitochondrial Function
Rui Chen discussed the long-term effects of lower concentrations of air pollution and potential therapies. Taurine ameliorated PM0.1-induced emphysema in mice by inhibiting oxidative stress and autophagy in the lungs. PM0.1, a toxic pollutant in diesel exhaust, causes mitochondrial dysfunction, and taurine showed potential in mitigating its effects.
Air Pollution and Cardiopulmonary Disease
Tang-Chun Wu highlighted the risks of indoor air pollution, particularly from solid fuel use in rural China, which is associated with higher cardiovascular, respiratory, and all-cause mortality. Switching to clean fuels and better ventilation can lower these risks. PAHs, especially from diesel exhaust and coal fires, cause DNA damage and increased frequency of micronuclei, a marker of genotoxicity. PAH exposure alters regulating microRNA and accelerates aging through DNA methylation.
Effects of Air Pollution on the Elderly
Song Tang discussed the greater impact of air pollution on the elderly. Personal monitoring for PM2.5 in healthy elderly individuals identified several responsive biomarkers and underlying mechanisms associated with PM2.5 exposure. PM2.5 exposure was linked to metabolic profiles in urine and serum and electrocardiographic changes.
COPD Hospitalization Expenditure due to Respiratory Tract Infections and COPD in China
Shao-Wei Wu analyzed national PM2.5 levels and hospital expenditure data from 2013 to 2017. Although PM2.5 levels decreased during this period, air pollution was still associated with increased hospital stays and expenditures, particularly for lower respiratory tract infections and COPD.
Lung Cancer Risk Assessment in Hong Kong, China
Lap-ah Tse linked air pollution to lung cancer, the leading cancer killer worldwide. The shift from squamous cell carcinoma to adenocarcinoma may reflect the larger influence of environmental factors. A screening algorithm developed in Hong Kong that considers air pollution predicted lung cancer risk better than other models.
Action for Clean Air in Cote d’Ivoire
Isabella Annesi-Maesano highlighted the significant air pollution problem in Africa, with about 700,000 deaths in 2012. PM2.5 is the major pollutant, with traffic, waste burning, and domestic fires being the primary sources. Cote d’Ivoire has implemented policies to reduce emissions and improve air quality.
Personal Intervention
Hai-Dong Kan discussed the reduction in air pollution in China over the past seven years. Air purifiers and respirators have shown some benefits in reducing inflammatory markers and blood pressure, but their effects on lung function and heart rate variability are mixed. More evidence is needed to support their use.
Clean Air Actions and Plans for China
Xiao-Ming Shi outlined China’s concerted efforts to reduce air pollution since 2013. The country has established 1436 monitoring sites in 338 cities to release hourly data on pollutants. Goals include eliminating coal-fired boilers and highly polluting cars, promoting clean energy, and upgrading standards and laws.
Air Pollution Effect Reduction: Planetary Health Approach
Josep Antó advocated for a planetary health approach, emphasizing that what is good for the planet is good for human health. Climate warming, microplastic particles, fertilizers, herbicides, insecticides, and antibiotics have negative effects on health and the environment. Health authorities and organizations should adopt regenerative health policies.
Political Action for Clean Air, Vilnius Declaration
Arunas Valiulis stressed the importance of political will in improving air quality. The Vilnius Declaration in 2018 sought to reduce air pollution and improve health through multi-sectoral involvement, new technology, and shared decision-making. Achievable goals and evidence-based guidelines are essential for success.
Conclusion
Air pollution is a global problem that significantly impacts health and longevity. It affects vulnerable populations more severely, contributing to heart attacks, stroke, and lung disease. Both indoor and outdoor air quality are important, with smoky homes accounting for over 4 million deaths annually. Air pollution and climate change are synergistic in their harm to health, and global warming exacerbates the effects of pollutants. Political will and public demand for clean air are crucial for reducing pollution at its source, which leads to prompt and significant health benefits.
doi.org/10.1097/CM9.0000000000000877
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