DALLAS — The impact of particulate matter air pollution on death and disability is on the rise worldwide, according to new research published today in the Journal of the American Heart Association, an open access, peer-reviewed journal of the American Heart Association.
Previous research established the association of particulate matter (PM) pollution to CVD death and disability. However, questions remain about the worldwide impact from this type of pollution and how it has been changing over time, the study authors noted.
“We focused on examining the burden globally because particulate matter pollution is a widespread environmental risk factor that affects all populations worldwide, and understanding its impact on cardiovascular health can help guide public health interventions and policy decisions,” said Farshad Farzadfar, M.D., M.P.H., D.Sc., senior author of the study and a professor of medicine in the non-communicable diseases research center of the Endocrinology and Metabolism Research Institute at Tehran University of Medical Sciences in Iran.
The researchers analyzed PM pollution as a risk factor for death and disability using freely available data from 204 countries collected between 1990 and 2019 and detailed in the Global Burden of Disease (GBD) study. Exposure to PM pollution was estimated using a tool from the 2019 update to the GBD study that incorporated information from satellite and ground-level monitoring, computer models of chemicals in the atmosphere and land-use data.
Among the many types of heart disease, the current analysis of cardiovascular disease is restricted to stroke and ischemic heart disease (a lack of blood and oxygen supply to portions of the heart, usually due to plaque build-up in the arteries) because the 2019 GBD study on the global burden of disease attributed to PM pollution only examined these two diagnoses. The Institute for Health Metrics and Evaluation (IHME), which provides the GBD estimates, only reports data for a certain risk factor if there is a large body of evidence about its association with a disease, Farzadfar noted.
“Until now, only the association of PM pollution with ischemic heart disease and stroke has been demonstrated in a large number of studies,” Farzadfar said. “The IHME may include other CVDs in the future. Moreover, ischemic heart disease and stroke contribute to a significant majority of CVDs, and our estimates, despite having limitations, may be used as a good estimate of PM pollution burden on CVDs.”
The investigators analyzed changes over time in years of life lost due to premature death (YLLs), years lived with disability (YLDs) and disability-adjusted life years (DALYs). DALYs is a measure that considers both the loss of life and the impact on quality of life to assess the full impact of a health condition on a population. The cardiovascular disease burden was assessed both overall and with age standardization, which compares health outcomes across a population with a wide range of ages.
The analysis found:
- The total number of premature deaths and years of cardiovascular disability from cardiovascular diseases attributable to PM air pollution rose from 6.8 million in 1990 to 8.9 million in 2019, a 31% worldwide increase.
- The increase in overall deaths was unevenly distributed, with a 43% increase among men compared to a 28.2% increase among women.
- Between 1990 and 2019, there was a 36.7% decrease in age-standardized premature deaths attributed to PM pollution, meaning that while fewer people had died from cardiovascular disease, people are living longer with disability.
- Regions with higher socioeconomic conditions had the lowest number of lost years of life due to cardiovascular disease attributed to PM pollution, yet also the highest number of years lived with disability. The opposite was true in regions with lower socioeconomic conditions, with more lives lost and fewer years lived with disability.
- Between 1990 and 2019, changes in the cardiovascular impact of PM pollution differed between men and women. In all measures, increases in disability and death from ambient PM air pollution were higher in men than women, while declines in disability and death from household PM air pollution were lower in women than men.
“The declines in deaths may be considered positive news, as they indicate improvements in health care, air pollution control measures and access to treatment. However, the increase in disability-adjusted life years suggests that although fewer people were dying from cardiovascular disease, more people were living with disability,” Farzadfar said.
The researchers also found that between 1990 and 2019, age-standardized CVD death and disability attributed to outdoor PM pollution rose by 8.1%, while age-standardized cardiovascular death and disability attributed to household PM pollution, which is produced by solid cooking fuels such as coal, charcoal, crop residue, dung and wood, fell by 65.4%.
“The reason for the decrease in the burden of household air pollution from solid fuels might be better access and use of cleaner fuels, such as refined biomass, ethanol, liquefied petroleum gas, solar and electricity. Moreover, structural changes, such as improved cookstoves and built-in stoves, chimney hoods and better ventilation, might be effective in reducing pollution exposure to solid fuels. Finally, the effects of educational and behavioral interventions should be considered,” Farzadfar said. “The shifting pattern from household air pollution due to solid fuels to outdoor, ambient PM pollution has important public policy implications.”
In a 2020 scientific statement and a 2020 policy statement, the American Heart Association details the latest science about air pollution exposure and the individual, industrial and policy measures to reduce the negative impact of poor air quality on cardiovascular health. Reducing exposure to air pollution and reversing the negative impact of poor air quality on cardiovascular health, including heart disease and stroke, is essential to reducing health inequities in Black and Hispanic communities, those that have been historically marginalized and under-resourced, and communities that have the highest levels of exposure to air pollution.
The study has several limitations. Because the assessment of exposure to particulate matter pollution in the study is based on regional estimates, it may not accurately reflect individual exposure. In addition, results from this analysis of the association between particulate matter pollution and cardiovascular outcomes may not be generalizable to other health conditions or other pollutants.
DALLAS — The combination of soaring heat and smothering fine particulate pollution may double the risk of heart attack death, according to a new study of more than 202,000 heart attack deaths in China. The study published today in the American Heart Association’s flagship journal Circulation.
"Extreme temperature events are becoming more frequent, longer and more intense, and their adverse health effects have drawn growing concern. Another environmental issue worldwide is the presence of fine particulate matter in the air, which may interact synergistically with extreme temperatures to adversely affect cardiovascular health," said senior author Yuewei Liu, M.D., Ph.D., an associate professor of epidemiology in the School of Public Health at Sun Yat-sen University in Guangzhou, China. "However, it remains unknown if and how co-exposure to extreme temperatures and fine particulate pollution might interact to trigger a greater risk of death from heart attack, which is an acute response potentially brought on by an acute scenario and a great public health challenge due to its substantial disease burden worldwide."
To examine the impact of extreme temperatures with and without high levels of fine particulate pollution, the researchers analyzed 202,678 heart attack deaths between 2015-2020 that occurred in Jiangsu province, a region with four distinct seasons and a wide range of temperatures and fine particulate pollution levels. The deaths were among older adults with an average age of 77.6 years; 52% were older than age 80; and 52% were male. Particulate exposure on the day of each death and one day before death were included in the analysis.
Extreme temperatures were gauged according to the daily heat index (also referred to as apparent temperature) for an area, which captures the combined effect of both heat and humidity. Both the length and extremeness of heat waves and cold snaps were evaluated. Heart attack deaths, or case days, during these periods were compared with control days on the same day of the week in the same month — meaning that if a death occurred on a Wednesday, all other Wednesdays in the same month would be considered control days. Particulate levels were considered high on any day with an average level of fine particulate matter above 37.5 micrograms per cubic meter.
"Our findings provide evidence that reducing exposure to both extreme temperatures and fine particulate pollution may be useful to prevent premature deaths from heart attack, especially for women and older adults," Liu said.
Compared with control days, the risk of a fatal heart attack was observed at the following levels:
The most common heart- or stroke-related diagnoses for women seen in the emergency department were high blood pressure (16% of visits), high blood pressure-related heart or kidney disease (14.1%) and atrial fibrillation (10.2%). The most common diagnoses for men were high blood pressure-related heart or kidney disease (14.7%), high blood pressure (10.8%) and heart attack (10.7%).
"Previous studies have shown sex differences in patterns of CVD among hospitalized patients," Mamas said. "However, examining CVD encounters in the emergency department provides a more complete picture of the cardiovascular health care needs of men and women, as it captures encounters prior to hospitalization." He also points out that previous studies of CVD emergency visits are limited to suspected heart attack visits. "Therefore, this analysis of 15 CVD conditions helps to better understand the full spectrum of acute CVD needs, including sex disparities in hospitalization and risk of death."
The study found that outcomes from the emergency CVD visits were slightly different for men and women. Overall, women were less likely to die (3.3% of women vs 4.3% of men) or be hospitalized (49.1% of women vs 52.3% of men) after an emergency department visit for CVD. The difference may be due to women’s generally lower risk diagnoses, said Mamas, but there could be an underestimation of deaths in women.
"We did not track deaths outside of the hospital setting," said Mamas. "Given past evidence that women are more likely to be inappropriately discharged from the emergency department, and strong evidence for the systemic undertreatment of women, further study is warranted to track outcomes beyond the emergency department visit."
An additional limitation of the data includes potential misdiagnosis errors in cases where the final diagnosis did not match the emergency diagnosis, particularly after a hospitalization and additional bloodwork and other health information could be obtained. Furthermore, the data is limited in that it does not capture information related to severity of disease, which may make comparisons around mortality differences between different patient groups challenging.
"Our work with this large, nationally representative sample of cardiovascular emergency visits highlights differences in health care needs of men and women, which may be useful to inform planning and provision of health care services," said Mamas. "We also encourage further research into understanding the underlying factors driving the differences in CVD patterns and outcomes between men and women."
