Public Health

CDC heat risk initiative, air pollution statistics and the latest news on bird flu in milk


AMA Update covers a range of health care topics affecting the lives of physicians, residents, medical students and patients. From private practice and health system leaders to scientists and public health officials, hear from the experts in medicine on COVID-19, medical education, advocacy issues, burnout, vaccines and more.

Is it too hot outside? What is the CDC doing for climate change? How bad is air pollution right now? What is particle pollution? Is milk safe to drink?

Our guest is AMA Vice President of Science, Medicine and Public Health Andrea Garcia, JD, MPH. AMA Chief Experience Officer Todd Unger hosts.


  • Andrea Garcia, JD, MPH, vice president, science, medicine & public health, American Medical Association

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Unger: Hello and welcome to the AMA Update video and podcast. Today, we have our weekly look at the headlines with the AMA's Vice President of Science, Medicine and Public Health, Andrea Garcia. I'm Todd Unger, AMA's chief experience officer. Welcome back, Andrea.

Garcia: Thanks, Todd, I appreciate the opportunity to be here.

Unger: Well, in addition to looking forward to summer and possibly cicadas here in Chicago, there is the possibility of, of course, extreme heat, and we're going to begin today's discussion with new heat guidance that was just released by the CDC. Andrea, tell us more about it and why it's needed right now.

Garcia: Well, Todd, hard heat-related illness has really been a growing public health concern both here and worldwide for some time now. Extreme heat events are becoming more frequent and more intense, and it really doesn't matter what state you live in. More than two-thirds of all people in the U.S. were under a heat alert at some point in 2023. And a recent report from the CDC found that daily emergency department visits due to heat-related illness peaked in several regions over the warm season months in 2023, and then they remained exceedingly high for an extended duration.

As you can imagine, these conditions can be especially dangerous for people with underlying health conditions. So in response to those increased health risks, the CDC, in partnership with the National Oceanic and Atmospheric Administration, or NOAA—there's National Weather Service—launched a new Heat and Health Initiative which is designed to protect people from heat exposure. And the CDC Director, Dr. Mandy Cohen, said heat can impact our health, but heat-related illness and death are preventable.

Unger: Andrea, tell us a little bit more about the initiative. Is it targeting patients or physicians?

Garcia: It's really targeting both and public health officials, too. So the initiative offers three new resources that, when combined, can help people be prepared, stay cool, stay hydrated and recognize the symptoms of heat-related illness. One resource is the Heat Risk Forecast Tool, and that provides location-specific seven-day heat forecast that tells people when temperatures may reach levels that could harm their health.

The methodology created by the CDC and NOAA pulls together health and temperature data to deliver that seven-day outlook. They use a five-level scale and the tool indicates how risky the heat level is in a specific area. The tool was really designed for public health audiences, including state and local health officials, and can help jurisdictions in implementing their heat response plans.

Unger: Now you mentioned there were three tools. What's the second tool and who's it for?

Garcia: Well, using data from the Heat Risk Forecast Tool, the CDC also created a Heat Risk Dashboard, and that was designed for the general public. That dashboard allows anyone to enter their zip code, receive a personalized heat forecast for their location and actions they can take to stay safe. That dashboard provides information on local air quality and other important heat and health information, and that's alongside new clinical guidance for people at higher risk who may need to take more protective actions.

Unger: Now given this is a pretty widespread problem, obviously we need to arm physicians with the proper information and guidance. What do physicians need to know now?

Garcia: Well, even though he can impact anyone's physical and mental health, children, especially those with asthma, pregnant women, older adults, and those with cardiovascular disease among other groups may be at greater risk of heat-related illness. The CDC's clinical guidance was developed to help health care professionals speak with their patients about heat and reduce the risk of negative health impacts due to heat exposure with special considerations for people with heart disease, children with asthma, and pregnant women.

That guidance helps doctors talk to patients about the negative health impacts of heat exposure and provides them with simple steps they can take to stay safe, and we'll include links in the description of this episode where physicians can find out more.

Unger: All right, Andrea. Thank you so much for that update. I mean, we've been talking about extreme heat and heat-related illnesses, but you also mentioned issues around air quality. Sometimes those go hand-in-hand, it seems, but a new report suggests that many of us are living in places with unhealthy levels of air pollution. Andrea, what can you tell us about that?

Garcia: Yeah, Todd, there was a new report from the American Lung Association which showed that nearly 40% of people in the U.S. are living in places with unhealthy levels of air pollution. And just to put that percentage into context, the number of people living with levels of air pollution that can significantly affect their health increased from about 119 million in last year's data to 131 million in the current data.

I think it's important to note that this year's State of the Air Report is using EPA's new more protective National Air Quality Standard for fine particulate pollution that allows for the recognition that many more people are breathing unhealthy air than was previously acknowledged under the previous standard.

But there are other contributing factors, including extreme heat, drought and wildfires. And as you know, wildfire smoke in particular is getting worse every year, and much of this is driven by climate change. 

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Unger: And indeed, I think many of us remember the wildfire smoke from fires in Canada last year creating a pretty surreal appearance in many cities across the country. Andrea, tell us a little bit more about the connection between the trend on air quality and our health. It seems pretty straightforward to understand, but how are physicians seeing this play out in their exam rooms?

Garcia: Well, one factor that researchers assessed was particulate matter or particle pollution. This is a mix of solid and liquid droplets that may come in the form of dirt, dust, soot, smoke and it's often difficult to see. Coal and natural gas-fired power plants create it, as do cars, agriculture, unpaved roads, construction sites and wildfires.

This pollution is so tiny, it's about 1/20 of a width of a piece of human hair. It can travel past our body's usual defenses and is associated with an increased risk of death from cardiovascular disease, respiratory disease and lung cancer. And then another factor is ozone pollution.

Unger: Well, tell us a little bit more about that. How does that differ in terms of its impact on air quality?

Garcia: Well, ozone pollution is the main ingredient in smog. It's formed from emissions from many sources, including cars, power plants and refineries. Exposure to ozone can exacerbate asthma symptoms. And people with long-term exposure to higher levels also face a higher risk of death from respiratory diseases.

As Harold Wimmer, who's the president and CEO of the American Lung Association, said in their news release, "Climate change is causing more dangerous air pollution every day that there are unhealthy levels of ozone or particle pollution. It means that someone—a child, a grandparent, uncle or mother struggles to breathe, and we must do more to ensure that everyone has clean air."

Unger: All right. And I know the AMA, for its part, has adopted policy nearly two years ago at its annual meeting to address climate change and declared climate change a public health crisis. Andrea, before we end today, I want to shift gears and talk about something we've been covering for the past few weeks, which is bird flu. This week's headlines were particularly concerning. Bird flu found in our milk supply. Tell us what's going on there and how worried do we need to be.

Garcia: Yeah. Last week, the FDA said that preliminary results from nationwide samples of retail milk indicated that about 1 in 5 samples were positive for traces of the bird flu virus. However, the agency added that so far the testing did not detect any live infectious virus in commercially sold milk.

They also acknowledged that it's too soon to know, though, with absolute certainty. The FDA has maintained that pasteurization should kill the virus, pointing out that avian flu doesn't stand up well to high temperatures, and past research on pasteurization indicates that it's very likely to effectively inactivate heat sensitive viruses like H5N1 in milk from cows.

The agency also said that to date, the retail milk studies have shown no results that would change its assessment that the commercial milk supply is safe. It did reiterate its longstanding warning against drinking raw milk. While these findings may not indicate dangers in our milk supply, they do speak to the broader question of how this virus is spreading.

Unger: What do you mean by that?

Garcia: Well, currently the virus has only been detected in a small fraction of dairy herds in the U.S. As of Friday, outbreaks have been confirmed in 34 dairy herds in nine states with the first outbreak in Colorado reported on the same day. But I think it's hard to know the significance of those numbers when we don't know the overall number of cattle tested.

The USDA has taken some new steps that could give us a clearer picture of the outbreak. There will now be mandatory reporting of positive tests in cattle and a requirement that dairy cattle test negative for the virus before they move across state lines. However, that testing only requires 30 animals in a given group no matter its size to be tested.

The other issue is that cattle may be shedding the virus without showing any obvious symptoms. Because milk from sick cows is supposed to be discarded, this is one possible explanation for how remnants of the virus entered the milk supply in the first place. A lot of testing is needed to understand the true scope of this issue, and we'll certainly continue to follow this as more information becomes available.

Unger: All right. Well, thank you so much for that update. That's where we'll end today. Andrea, again, appreciate you being here and keeping us informed. Everyone out there who's listening or watching, if you found this discussion valuable, you can support more programming like it by becoming an AMA member at We'll be back soon with another AMA Update. In the meantime, you can find all our videos and podcasts at Thanks for joining us. Please take care.

Disclaimer: The viewpoints expressed in this video are those of the participants and/or do not necessarily reflect the views and policies of the AMA.

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