On this week’s episode, Dr. Stacey Alexeeff and Dr. Jamal Rana discuss how wildfires impact people with cardiovascular diseases (CVD) and how physicians can help vulnerable patients stay prepared.

Dr. Alexeeff: I’m Stacey Alexeeff. I’m a research scientist and biostatistician at the Kaiser Permanente Division of Research, and I’ve been studying the health effects of air pollution for more than 15 years. Unfortunately, with these increasing wildfires generating more pollution, we have more to study and be concerned about.

Dr. Rana: I’m Jamal Rana. I’m a cardiologist at Kaiser Permanente, and I’m also a clinical investigator with the Division of Research.

Before we go into wildfire-related air pollution and exposure to cardiovascular risk assessment (especially for patients who have preexisting CVD), at the foundational level, it’s good to understand that data are very concerning overall regarding the association between air pollution and heart disease. Many physicians don’t even realize that of all the side effects of air pollution, CVD is the number one killer, according to Global Burden of Disease consortium data. Of the 9 million deaths that occurred in 2019, over 5 million were due to CVD. Having that knowledge, both from physician and patient standpoints, is the first step. Once recognizing that high pollution can cause high CVD burden, there are many contributing mechanisms.

I tell patients that if there are high pollution days, it can cause inflammation in your heart, more clotting, endothelial dysfunction—what we call “oxidative stress.” All those things can trigger a heart attack or can have delayed risk effects on your heart arteries, so if you have preexisting disease, you must be extra diligent about taking your cardiac medications. Also, be aware of outdoor pollution. On days where air quality is not good, you should be more diligent about wearing masks. I think in the post-COVID era, it has become easier to raise awareness about wearing a mask, which we did not see as much in the pre-COVID era.

Dr. Alexeeff: Yeah, I think that’s great, Jamal. This is why they developed the air quality index. The APA has some guidance saying anyone with preexisting cardiovascular disease is considered a sensitive subgroup. We have the air quality index that goes from good to moderate to unhealthy for sensitive groups. That includes the entire population of patients with preexisting CVD. It’s just like you said, Jamal: when the air quality is at that level, those patients need take protective actions such as limiting time outdoors, wearing an N95 mask when outdoors, and running an air purifier in their home.

To that point, I think it’s become easier now. There are weather apps. Having patients keep a lookout for those, especially on wildfire days, is key.

In our study, we found a 23% increased rate of cardiovascular events and 35% increased rate of death when the air pollution was high during the Mendocino Complex Fire. But later in November, during the Camp Fire, we did not see any increased risk of events. That was surprising.

We have several hypotheses, which we discussed in the paper. One possibility is “depletion of the susceptibles.” That’s the idea that among people who were the most susceptible to having wildfire pollution trigger a cardiovascular event, that event was triggered when they were exposed to higher air pollution during the Mendocino Complex Fire earlier in the season. Once they experienced those events, there were fewer people at a similar risk level ready to be triggered by pollution. One of our anonymous peer reviewers thought this was an important point and very plausible.

Another reason that this could have happened is greater public awareness, and people could have changed their behavior during the Camp Fire. We did a post-hoc analysis of Google Trends data and found that searching for terms like “wildfire smoke,” “air quality,” and “N95 mask” was highest during the Camp Fire, and it was much lower during the Mendocino Complex Fire. There was a lot of media coverage during the Camp Fire, too. On one day during the Camp Fire, the air pollution in the Bay Area reached the highest level in the entire world. I remember that being a big news story, and people were paying attention, so it could be that people were more aware of bad air quality and limited their time spent outdoors.

We did see some people wearing N95 masks. I personally remember wearing my N95 mask. As Jamal said, this was the pre-COVD era, so we didn’t all just have N95 masks sitting around. I got an N95 mask and wore it on my way to work, and I saw some other people wearing masks, too. That’s anecdotal. Then, in this post-hoc analysis that we did, there was some evidence that people were more aware during the Camp Fire.

If people were taking action to protect themselves, that could be why we didn’t see an increased rate of cardiovascular events and death. It’s important to study that more in future research.

Dr. Rana: What can we do once the wildfire smoke is spreading everywhere? For healthcare systems, there could be a considered effort to send a mass message to patients that there are fires. Along with all the other things people are worried about, just be extra careful that this pollution can exacerbate your heart and lung disease. Public messaging, or messaging direct from the healthcare system to their patient, can be very helpful for extra awareness. We can’t presume that everyone realizes the danger, especially when they are worried about so many other things.

The other issue that comes up is that it’s a stressful time for the folks who lost their homes. It can be devastating, psychologically. That mental stress can have a direct effect on the heart. For instance, there is what we call stress cardiomyopathy, or Takotsubo syndrome, where acute stress can cause heart failure. Studies have shown that the smoke and stress can trigger a heart attack. People need to be aware of those symptoms, that if they suddenly have shortness of breath, it could be acute heart failure, so call 9-1-1 or seek care.

Finally, the extra smoke and stress can also trigger arrhythmias or irregular heartbeats, so people start having palpitations. All those things can be summarized as what to look out for and when to seek healthcare.

Dr. Alexeeff: As Jamal said, there are individual protective actions that people can take. Certainly, we need more physicians to be talking to their patients about what they can do and raising awareness of the health effects of air pollution. We’ve seen public officials sending out messages, but are those messages reaching patients? Are patients aware? I think physicians are the best point of contact to the patients. We’re empowered by technology, so it is even helpful just to make patients aware they can check their phone for the current air quality or the forecast for the next day.

Also, people don’t need to wait for the fire to happen to be prepared. You can get an N95 mask and an air purifier today so that you can be prepared when the next wildfire happens, the same way we prepare for other of emergencies. Unfortunately, having large wildfires blowing smoke and causing poor air quality is becoming a regular emergency that people might encounter—and not just in California. We saw that with the Canadian wildfires that blew smoke all the way to the east coast, causing terrible air quality. It is worth being prepared.

Dr. Rana: Unfortunately, not only within our lifetimes but within the last 5-10 years, we’ve seen an increasing frequency of these devastating events. More than just the individual level, I think we need societal policies to mitigate these events. Climate change is an existential crisis. Advocacy and policy changes are important. As a society, what can we do?

We already mentioned the individual level—how we can take care of ourselves as a patient or physician. But another example is the fact that Dr. Alexeeff and I joined forces to explore the impact of pollution on heart disease. This is where physicians and scientists come together. More such work needs to happen, and more awareness and advocacy are the ways to go.

Dr. Alexeeff: I agree, Jamal. The best long-term strategy is to all do our part to reduce the impacts of climate change by reducing greenhouse gases. We know wildfires are increasing because of climate change, and unfortunately, if climate change continues to get worse, we’re expecting even more wildfires affecting more people.

Healthcare systems can take action to reduce their greenhouse gas emissions. Kaiser Permanente has made huge efforts to reduce the greenhouse gas emissions of our healthcare system and to become carbon neutral.

There are a few important areas that we should explore in future research. One thing we mentioned earlier is that we consider patients with preexisting CVD to be a sensitive group that we need to be concerned about. We need more research to understand which cardiovascular conditions make people the most susceptible to wildfire air pollution.

Right now, we lump everyone with preexisting CVD into one group and say they’re all sensitive, but we know it’s much more complicated. There are many different types of underlying cardiovascular conditions. It is important for clinicians to have better knowledge of which patients they need to be the most concerned about and ensure take the most protective actions.

Building on our conversation about the different outcomes between the two fires, we need to research which actions people have been taking during wildfires and try to quantify, rigorously, what the impacts are. How many lives are we saving with public health warnings and people taking individual actions? Then, we can figure out how many more lives could we save if even more people were taking those actions. Those are really important areas of research, and I hope we’ll be working on both of them in the future.

Dr. Rana: I would add that, from sense of optimism and courage, our cardiovascular professional societies such as the American College of Cardiology and American Heart Association are increasingly publishing data, review articles, and campaigns to raise awareness about this very serious matter.

Dr. Alexeeff: Unfortunately, this is a very timely topic and something that we all need to be concerned about.

Dr. Rana: Absolutely. Unfortunately, the frequency of such tragic events may get even worse in coming years unless we start taking action today.

Thanks for listening. Stay tuned for next week’s episode. To hear more, follow PeerPOV: The Pulse on Medicine on Apple Podcasts, Spotify, or Amazon Music.

This transcript has been edited for readability.