‘There are no safe levels of pollution’: an interview with wildfire researcher Sam Heft-Neal | Climate crisis


As the climate crisis brings drought and dried-out landscapes, wildfires in the US west are spreading smoky air to millions of people, even those who live far from where the fires burn. The problem is becoming so pronounced that some television weather forecasters in California now include “smoke casts” in their reports, displaying models that predict where smoky air from a wildfire will travel days into the future.

Wildfire smoke in recent years accounted for up to 50% of all dangerous, small particle air pollution in the western US, research shows, and the problem is growing.

The largest fire to hit California this year, the McKinney fire, is raging through the Klamath national forest.

Scientists warn that current health policies are not effectively protecting people against smoke inhalation dangers, and a new study published in July underscored how dangerous levels of tiny pollution particles in wildfire smoke travel into households not threatened by the fire itself.

The Guardian spoke with one of the authors of that new study: Sam Heft-Neal is a wildfire researcher at Stanford University’s Environmental Change and Human Outcomes Lab (ECHO).

What was the most striking finding of the study?

One is that even if you look at really high-income homes around the [San Francisco] Bay Area, their indoor air quality is really poor during wildfires on average. That surprised me. I thought that wealthy people who care about air quality would be able to protect themselves effectively. And that does not seem to be the case. That’s concerning, because we expect many groups to be less able to protect themselves.

What do you think the implications of the study are for policymakers?

Wildfire pollution is just fundamentally different from other types of pollution. When there’s pollution from transportation, it’s relatively straightforward to try to reduce the pollution source by regulating vehicle emissions and taxing gasoline or whatever policymakers want to do. But that’s really hard to do with wildfires. There’s no policy we can implement that will eliminate or reduce wildfires dramatically in the short run. And so instead, the main policy is just telling people to protect themselves.

So I think there has to be huge efforts to try to identify the vulnerable populations and help them protect themselves. So you’re not just leaving everyone to their own devices. That’s just going to exacerbate existing inequalities.

Asthma patients are often among those most affected by wildfire smoke. According to CDC data from 2016-2018, Puerto Ricans have the highest asthma rates of any ethnic group in the US, followed by African Americans. What measures could be taken to address vulnerable populations?

The most effective measure would be to provide air purifiers to vulnerable households. Maybe that means low-income households. It could certainly mean people with asthma or other respiratory issues that are going to be exacerbated.

In California, the Bay Area Air Quality District, for example, has a program to loan out air purifiers during bad wildfires. It’s just a really expensive policy that is difficult to implement at a broad scale. But efforts are under way to try to expand these, because if you are able to keep your windows and doors shut and stay home and turn on an air purifier, it seems like the best way to protect yourself.

What about using N95 masks?

N95 masks are definitely effective if you need to go outside. They have to be worn effectively. A lot of people wear N95 masks too loose and so they’re not that effective. But when they’re worn effectively, they definitely alleviate the problem when you’re outdoors.

What other research is happening in the world, as we’re all looking at the news and seeing fires and heatwaves all over Europe?

There are several main takeaways from recent work. One is that there are no safe levels of pollution. You see health impacts even at really low levels. So really, there’s no safe level of exposure.

And the second main point is that people had initially hypothesized that pollution from wildfire smoke might be less harmful than pollution from other sources. And that does not seem to be the case. It looks like wildfire smoke is just as bad as pollution from other sources.

Last year there was a study showing that California fires increased hospital visits on the east coast. Smoke can be transported very far and can really impact pollution levels all over.

What are you working on now?

One of the real unanswered questions is trying to understand what drives the differences in indoor air quality. Even neighboring households can have very different indoor air quality. And that’s true even once you account for the year people’s houses were built, whether they have air conditioning, all these other things.

And we’re really interested in monitoring lower-income households. We want to learn more about households that don’t necessarily have the resources to buy their own air quality monitors.

Who’s measuring the global pollution impacts?

That’s a really promising new avenue of research that’s progressed quickly. The European Space Agency put up a new satellite three or four years ago that has sensors specifically designed to monitor pollution. That has really given us new insights into global pollution patterns, because you can see pollution every day everywhere in the world.

And you can break down the types of pollution using satellite data. We still don’t have the historical records that we would need to study long-term impacts … but we can at least now see what current pollution patterns look like and see how movements are progressing.

  • This story is co-published with The New Lede, a journalism project of the Environmental Working Group.