Clearing the air about climate change

Climate change is a public health issue, and physicians should be aware of the potential medical consequences and be able to communicate those to patients.

Increasingly, patients are asking more questions about the health risks associated with climate change, said Douglas DeLong, MD, FACP, chief of the division of general internal medicine at Bassett Healthcare Network in Cooperstown, N.Y. He recalled a recent conversation he had with a patient about the Zika virus. “One of her concerns was should she delay pregnancy this summer?”

Dr. DeLong, vice-chair of ACP's Health and Public Policy Committee, which recently developed a position paper on the subject, said that doctors can play a role in the conversations around climate change, not just by discussing potential health effects with patients but also by advocating for policies that might help mitigate the environmental threat.

Illustration by David Cutler
Illustration by David Cutler

The position paper, which was published online April 19 in Annals of Internal Medicine, relied on an evidence-based approach and encouraged physicians to “become educated about climate change, its effect on human health, and how to respond to future challenges.” The paper also recommended that physicians, both individually and collectively, “advocate for climate change adaptation and mitigation policies” along with communicating about related health issues with the public and policymakers.

“I think it's a general recognition that climate change is a public health issue, maybe even the most important public health issue of our generation,” said Dr. DeLong. “I think it's the obligation of physicians to be aware of the potential medical consequences. They don't necessarily have to become proselytizers or necessarily advocates. But I think they do need to become educated.”

The position paper, which Dr. DeLong noted was developed and approved through a lengthy ACP process, including outside review, joins a growing list of papers by medical organizations expressing concerns about the health impact of climate change, including the American Academy of Pediatrics and the American Thoracic Society, among others. Along with outlining the scientific evidence tracking rising temperatures, the paper also discussed related health impacts, ranging from heat stress to respiratory disorders to concerns that a warmer environment will more quickly spread mosquito-borne and other diseases.

Individual doctors also should consider speaking up if they're concerned, including by discussing climate change with patients, said Joel Kaufman, MD, MPH, FACP, a professor of environmental and occupational health sciences at the University of Washington's School of Public Health in Seattle. The position paper provides physicians “a license as it were to become a bit of an advocate on this issue,” he said, noting that adopting such a stance requires doctors to shift beyond patient health into policy.

“It gets them out of their comfort zone, because it's not necessarily what they feel like they were trained to do,” Dr. Kaufman said. “But in fact because they are the most scientifically trained people that their patients are likely to see, they are actually in a good position to step out on it.”

Heat effects

The planet's average surface temperature has increased by 1.4 degrees since 1880, and 2015 was determined to be the earth's hottest year on record, according to research cited in the paper. Heat can pose a significant stress on the body, not only directly in terms of heat exhaustion but by exacerbating underlying cardiovascular or respiratory conditions, the paper said. Roughly 70,000 premature deaths in Europe were connected to the 2003 heat wave, according to 1 study cited.

It is not just obviously extreme heat conditions that are associated with health risks. Even moderate temperatures that are significantly elevated above the usual warm season conditions for a given location can exert substantial public health impacts, said Helene Margolis, PhD, who studied hospitalizations and emergency department visits during California's heat wave of 2006. The unusually high temperatures, with both extremely high daytime maximum temperatures and high nighttime minimum temperatures, affected much of the state, with the Central Valley experiencing daytime temperatures of 100 degrees or more for most of the 2-week heat wave.

During that 2-week stretch, many excess clinical contacts, 16,166 to the emergency department and 1,182 hospitalizations, were calculated statewide compared with non-heat wave periods in the same summer, according to an analysis published in January 2009 in Environmental Health Perspectives.

Somewhat surprisingly, it was the relatively cooler Central Coast region, which includes San Francisco, rather than the Central Valley that saw the greatest increases in emergency department visits for heat-related causes, said Dr. Margolis, an associate adjunct professor of medicine in the department of internal medicine at the University of California, Davis. While it's not clear why, a theory is that San Francisco residents are accustomed to cloudy cool days in the summer, rather than watching the mercury reach 80 degrees and beyond, she said.

“These are people who are not as acclimatized to warmer temperatures; taking advantage of the sunny days they probably went out and exerted themselves resulting in heat stress and illness,” she said. “Notably, the Central Valley saw the greatest increase in hospital admissions, perhaps reflecting the more extreme temperatures and different population vulnerabilities in that region.”

As temperatures edge upward, doctors should watch out for vulnerable patients, whether it's those with respiratory conditions and other chronic diseases such as cardiovascular disease or diabetes, those who have neurologic conditions, or those taking medications that affect thermoregulation and make it more difficult for their bodies to manage heat exposure, Dr. Margolis said. If the patient works outside, stress the importance of drinking water and breaks in the shade, she said. Check which patients have air conditioning at home and whether they use it, and for those who don't, ask about their backup plan in the event of a heat wave, she said. For children or elderly patients, it is critical that caregivers are informed of the risks, signs of heat stress, and prevention measures.

Doctors can give patients handouts to further emphasize the physical stress of heat and ozone, among other climate risks, said Catherine Thomasson, MD, an internist and executive director of Physicians for Social Responsibility. Also, tell patients directly why they might be personally vulnerable, for example, by saying, “You are an elderly person on a diuretic medication, and you're more at risk of having a heat stroke when there is a heat wave.”

Similarly, with air pollution, state the climate change connection as a way to educate patients on the concern and related health risks, Dr. Thomasson said. “I wouldn't belabor it,” she said. “I would say that climate change is increasing the level of pollen, the length of the pollen season, and ground-level ozone, and all of these things can make your asthma more likely to flare and have worse attacks.”

ACP's position paper stated that climate change “may already be having a troubling effect on respiratory health.” Some 7 million deaths worldwide in 2012 could be connected to the joint effects of outdoor air pollution and household indoor air pollution, according to a World Health Organization report that was cited.

Dr. Kaufman, principal investigator of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), a federally funded study on air pollution, said that such research already shows that air pollution can be linked to atherosclerosis. The 10-year study involved nearly 6,800 participants. Recent findings, published online May 24 by Lancet, have shown that exposure to air pollution accelerates the cardiovascular process, as measured by calcium deposits in the coronary arteries.

By using coronary artery calcification as a surrogate for the development of atherosclerosis, researchers monitored change over the course of a decade and found that pollution exposure could pose additional cardiovascular risk, Dr. Kaufman said.

“I think it's probably fair to say that the difference between the most polluted areas of a major urban area and the least polluted areas of a major urban area were on par with cardiovascular risk factors like diet and exercise that internists spend a lot of their time thinking about,” he said.

Other climate change links

Vector-borne diseases also are discussed in the ACP position paper, including malaria and West Nile virus, although the degree to which they can be linked to climate change varies. The mosquito-borne disease Zika has dominated the news in recent months, but the species involved, the Aedes aegypti, has long been present in the United States. “It is likely an example of a vector-borne disease that is being further transported,” Dr. Thomasson said.

A better example is Lyme disease, which is transmitted by infected deer ticks and is moving across the United States as winter cold snaps become less frequent, she said. Maps from the CDC document the migration of Lyme, which is gradually moving southward from regions of the Northeast and upper Midwest, where it was initially confined. ACP's position paper also points out that West Nile virus may be transmitted into drought-prone areas when birds and other vectors turn to water sources used by humans.

Other health ripple effects have been correlated with rising temperatures, Dr. Thomasson said. Heat can aggravate underlying volatile tempers and temperaments, resulting in more conflict, including domestic violence, she said. Climate effects also can undercut emotional resilience. Nearly half of New Orleans residents surveyed reported anxiety mood disorder following Hurricane Katrina, according to a 2007 study cited in the ACP position paper. Dr. Thomasson also noted that some hospitals closed after the post-Katrina flooding, a hit to the local health system.

Still, physicians should be careful to put climate-related health risks into context as they discuss health threats with their patients, Dr. Kaufman said. For example, most patients shouldn't be allowed to use ozone worries as an excuse to skimp on outdoor exercise, he said. “For almost everybody on almost every day in the United States, the benefits of exercise are going to be more important than the concerns about air pollution,” he said.

But patients with lung difficulties should be cautioned to limit physical activities on high-ozone days. Also, educate patients that if they have a choice of where they run or work out, look for a location away from a polluted area such as a busy roadway, Dr. Kaufman said.

Communication challenges

Dr. DeLong, a geriatrician, said he's tried to help local clinicians by giving grand rounds about climate change and health effects, and he's considered writing an op-ed to raise heat awareness. Another way doctors can get involved is to find out more about how their local communities protect agricultural workers and others who labor outside all day in the sometimes blistering sun, Dr. Margolis said. For example, she pointed out, are there any rules about water and shade breaks? Doctors can bring their clinical expertise to bear in these areas by speaking up, she said.

Dr. DeLong acknowledged that there are still some people who are “not buying into the climate change argument.” Within the ACP membership, there has been some pushback about why the organization is getting involved with this issue, “but surprisingly very little,” he said, with more positive feedback from members.

“From the ACP point of view, we're experts at health care,” he said. “We're not experts at politics. But there is an interface between medical knowledge and policy, and I think that's what we're trying to straddle somewhat.”

Dr. DeLong also can't recall any patients getting irritated when he's discussed health concerns in the context of the changing climate. “If I did get some pushback from patients, I would say, ‘Well, I respectfully disagree. But let's agree to disagree and move on.’”

Dr. Thomasson agreed with that approach, saying that doctors should drop the subject rather than interfere with the doctor-patient relationship. “The most important thing is taking care of that patient in that moment,” she said.

So how did Dr. DeLong counsel the woman contemplating pregnancy who was worried about the Zika virus? “I said that I thought the risk was miniscule here,” he said, noting that his practice is based in New York State. “It would probably have been a different answer if I was in Houston, Texas.”