NEJM Calls Global Warming 'Major Public Health Emergency'

New England Journal of Medicine editorial, articles, and interactive feature spotlight intersection between global warming and healthcare.

In an editorial, three articles, and an interactive feature that includes the impact of climate change on a dozen medical specialties, the New England Journal of Medicine has declared the Earth's ailing atmosphere a "major public health emergency."

At least 97% of actively publishing climate scientists believe the planet's atmosphere is warming and human activity is a primary driver of the process. In addition to healthcare impacts such as air pollution, climate change has been linked to several existential threats to human populations, including sea level rise, extreme weather events, insect-borne diseases, and drought.

"The stark reality is that high levels of greenhouse gases caused by the combustion of fossil fuels—and the resulting rise in temperature and sea levels and intensification of extreme weather—are having profound consequences for human health and health systems," the NEJM editorial says.

The negative effects of climate change on health and healthcare organizations—including damage to public health infrastructure such as flooding, heat-related illnesses, increased pollen fueling allergies and exacerbating asthma, disrupted supply chains, and rising insect-borne diseases—demand a response from the healthcare sector, the editorial says.

"We, as a medical community, have the responsibility and the opportunity to mobilize the urgent, large-scale climate action required to protect health—as well as the ingenuity to develop novel and bold interventions to avert the most catastrophic outcomes."

The three articles NEJM published last week explore climate-sensitive disease, easing of regulations at the Environmental Protection Agency, and air pollution's impact on mortality.

1. Climate-sensitive disease
 

Global warming is linked to the spread of chronic kidney disease of unknown origin (CKDu) around the world, according to "A New Era of Climate Medicine—Addressing Heat-Triggered Renal Disease" by Cecilia Sorensen, MD, and Ramon Garcia-Trabanino, MD.

"CKDu was first described in El Salvador in the 1990s, when unusually large numbers of agricultural workers began dying from irreversible renal failure. It quickly became evident that the phenomenon was pervasive among innumerable agricultural communities in hot, humid regions of Central America. CKDu's presence is now potentially global, with similar disease patterns observed in North America, South America, the Middle East, Africa, and India," Sorensen and Garcia-Trabanino say.

Although several factors may contribute to CKDu, heat exposure is a primary driver of the disease, they say. "What we do know for certain is that CKDu is related to heat exposure and dehydration, although exposure to agrochemicals, heavy metals, and infectious agents, as well as genetic factors and risk factors related to poverty, malnutrition, and other social determinants of health may also contribute."

The increasing reported cases of CKDu in areas of the world that have experienced relatively high temperatures in recent decades shows an ominous link between global warming and illness, Sorensen and Garcia-Trabanino say.

"We may have now reached a physiological limit, in terms of heat exposure, at which acclimatization and behavioral modifications can no longer overcome the biologic stressors of unsafe working conditions and environmental exposures in these hot spot communities. We are now living in an era when climate change is no longer a distant, existential threat. It is happening now, and it is affecting human health in profound ways."

2. Easing of environmental regulations
 

The medical community needs to take a stand against easing of Environmental Protection Agency regulations, according to "Combatting EPA Rollbacks—Health Care's Response to a Retreat on Climate" by former EPA Administrator Gina McCarthy, MS, and Aaron Bernstein, MD, MPH.

"We can demand that proposed climate policies come with a credible accounting of their health effects. We can prioritize research evaluating the health effects of carbon-reduction strategies. We can discuss climate action in ways that make it personal, telling stories about the people we see in our clinics, hospital beds, and emergency departments whose health has been compromised by climate change, in an effort to educate and influence the media, decision makers, and parents," McCarthy and Berstein say.

The EPA has eliminated or weakened air pollution regulations on several fronts, including fuel-efficiency standards for cars, greenhouse gases such as methane, and mercury emissions.

"Burning fossil fuels generates roughly 80% of our country's carbon pollution and the bulk of other air pollutants known to cause or exacerbate a host of ailments, including everything from chronic obstructive pulmonary disease, myocardial infarction, and stroke to lung cancer, type 2 diabetes, pneumonia, and possibly even dementia," McCarthy and Berstein say.

3. Air pollution and mortality
 

In "Ambient Particulate Air Pollution and Daily Mortality in 652 Cities," Cong Liu, MS, et al., found a positive association between increases in particulate matter (PM) pollution and all-cause, cardiovascular, and respiratory mortality. PM is generated in combustion such as power plant operations or formed through atmospheric chemical transformation.

The key findings of the research focused on two classes of PM pollution: PM with an aerodynamic diameter of 10 μm or less (PM10) and fine PM with an aerodynamic diameter of 2.5 μm or less (PM2.5).

• An increase of 10 ug per cubic meter of PM10 concentration was linked to a 0.44% increase in daily all-cause mortality, 0.36% increase in daily cardiovascular mortality, and 0.47% increase in daily respiratory mortality
   
• An increase of 10 ug per cubic meter of PM2.5 concentration was linked to a 0.68% increase in daily all-cause mortality, 0.55% increase in daily cardiovascular mortality, and 0.74% increase in daily respiratory mortality

The stronger association between PM2.5 exposure and mortality may be because this class of PM has more small particles that can absorb toxic materials in the air and lodge deep in the lungs, Liu and his coauthors wrote.

The data, which was collected from 1986 to 2015, shows a correlation between PM pollution and mortality, they wrote. "Our multi-country time-series analysis provides evidence on positive associations between short-term exposure to PM10 and PM2.5 and daily all-cause, cardiovascular, and respiratory mortality. This study indicated independent associations of PM10 and PM2.5 concentrations with daily mortality after adjustment for gaseous pollutants."