Dangerous Air

Country/area: United States

Organisation: The California Newsroom, a collaboration of California public radio stations, NPR and CalMatters.

Organisation size: Big

Publication date: 28/09/2021

Credit: Alison Saldanha, Farida Jhabvala Romero, Caleigh Wells, Aaron Glantz, George LeVines, Scott Rodd, Adriene Hill


Alison Saldanha was the lead data journalist for The California Newsroom’s Dangerous Air investigation. She was also part of The New York Times’ graphics department, running the admin for its Pulitzer Prize-winning COVID-tracking project, and a correspondent for its Midwest bureau. In 2019, her project tracking religious hate crimes across India won the Global Editors Network Data Journalism Award for a small newsroom. Alison is now a graphics reporter for The Seattle Times. 


Farida Jhabvala Romero is a reporter for KQED and The California Newsroom. She has reported extensively on immigration, and most recently, on wildfire smoke and its impact on communities. She was part of a team of journalists who won a national Edward R. Murrow award in 2020 for the series titled, “Graying California.” Before joining KQED, Farida worked as a producer and reporter at Radio Bilingüe, a national radio network. 


Caleigh Wells is a reporter and producer at KCRW in Los Angeles. In 2021 she co-hosted KCRW’s “Wasted” series, led the station’s coverage on COVID vaccines and aided a statewide investigation on California’s wildfires. She regularly reports on climate change and public health. When she’s not reporting, she fills in for her colleagues as a host or producer on Morning Edition, All Things Considered, Press Play and Greater LA. 


Aaron Glantz is The California Newsroom’s senior investigations editor. His work has sparked dozens of Congressional hearings, numerous laws, and criminal probes by the DEA, FBI, Pentagon and Federal Trade Commission. A two-time Peabody Award-winner, finalist for the Pulitzer Prize, multiple Emmy nominee, and winner of the Selden Ring and Alfred I. duPont-Columbia Award, his work has appeared in New York Times, Chicago Tribune, NBC Nightly News, Good Morning America and the PBS NewsHour. A former senior reporter at Reveal and JSK Fellow at Stanford University, his books include Homewreckers, The War Come Home and How America Lost Iraq.


Scott Rodd covers California state government for CapRadio in Sacramento, with a focus on wildfire response and prevention policy.


George LeVines is a data journalist in The California Newsroom. His current work covers the environment, police surveillance, racial justice and more. He enjoys riding motorcycles whenever possible. 


Adriene Hill is The California Newsroom’s managing editor. A public radio veteran, she was previously the managing editor of the Los Angeles public radio station, KPCC, and also served as a correspondent and fill-in host for the public radio business program Marketplace. 

Project description:

The scourge of climate change devastates the American West. More than 7.3 million acres burned in California’s wildfires alone in the last two years. Vast amounts of soot foul the air, entering hearts and lungs. Yet the phenomenon is so new that peer reviewed science hasn’t caught up. Our collaborative investigation, Dangerous Air, turned satellite images into data, allowing us to map the menace of growing smoke exposure down to ZIP codes. We linked that growth with rising hospitalizations and asthma prescriptions, and showed how California wildfires impact cities like Philadelphia and Washington D.C., thousands of miles away.

Impact reached:

The impact of our Dangerous Air investigation has been immediate, far-reaching and is ongoing. Lawmakers in both Sacramento and Washington have called for hearings. A raft of legislation has been promised for the new year covering everything from additional worksite protections for farmworkers to the construction of federally-funded air shelters for “smoke refugees” who need a safe place to breathe. A story included in the supporting materials provides further details on the actions lawmakers are taking in response to Dangerous Air. 

This resounding impact was built both on the strength of the reporting and the power of a collaborative model that serves as a force multiplier for the entire media ecosystem. Customized stories produced as part of this series ran on NPR’s national shows and in hard-hit rural communities that are most impacted by the blazes. We showed clearly why these stories mattered to particular communities and to the nation as a whole and what leaders at each level could be held accountable for.

Before the investigation publication, we also convened a national webinar for local journalists, showing them how to report on the impact of California wildfire smoke drift over their region. The reporting tools we developed led to localized accounts of wildfire smoke risk produced by newsrooms in places as different as Seattle, St. Louis, Denver, and Columbus, Ohio, where the local NBC affiliate leveraged our data analysis to show how smoke from California wildfires was lowering crop yields in the Midwest, by stifling sunlight and preventing photosynthesis.

In sum, Dangerous Air has changed the national conversation, demonstrating that California’s climate-induced wildfires are a threat not only to people of the Golden State, but the health of the entire nation.

Techniques/technologies used:

Dangerous Air revealed how climate-change fueled wildfires in California impact the air people breathe across the U.S. 

A detailed account of how we took images from the National Oceanic and Atmospheric Administration’s Hazard Mapping System into localized data can be found in a “how we did it blog” in the supporting materials section. 

We used Big Query and Python to clean this data and ready it for analysis and visualization. We divided the dataset into two periods, defining 2009 to 2013 as the “base period” when extreme fire events weren’t as frequent and 2016 to 2020 as the “current period” and calculated the average smoke days per ZIP code. We then quantified the change in smoke exposure over time and placed the ZIP codes within their city, county and state limits. We merged the resulting dataset with geospatial data to build an interactive choropleth map in Mapbox. In Excel, we analyzed the EPA’s regional data on PM 2.5 pollution over 20 years to provide context. We used Datawrapper to visualize our findings. 

To determine the impact on health outcomes in California specifically, we analyzed Office of Statewide Health Planning and Development’s (OSHPD) data on every hospital discharge for respiratory and cardiovascular conditions between 2016 and 2019. With each hospital’s unique OSHPD ID, we geocoded the dataset and merged our smoke days dataset at ZIP code level. We aggregated this to regions delineated by the California Hospital Association for the best estimate of how patients may move across county borders.

We also dug into Centers for Medicare and Medicare Services’ open data (available for 2013 to 2018) to analyze the growth of federally funded prescriptions for albuterol, a common asthma medication. We filtered for California’s data and refrained from further analysis without more specific temporal data. 

What was the hardest part of this project?

Our initial instinct to quantify the impact of wildfire smoke on air quality and human health was to use EPA data on PM 2.5 fine particulate matter. PM2.5 is one of the primary (and most dangerous) pollutants in wildfire smoke. These tiny bits of airborne ash are 30 times smaller than the width of a strand of human hair and can be inhaled deep into the lungs, and even enter the bloodstream. 

However, we quickly learned that the EPA’s measurement of the PM2.5 pollutant would not isolate wildfire smoke as the cause for pollution, rendering our investigation ineffective and prone to errors. Further, the EPA monitors do not run every day in every zip code in the U.S. In fact, there were many counties without a single EPA monitor. The data as it existed did not allow us to expand our investigation to every part of the country, nor did it allow us to meaningfully localize our findings. We spent months talking to scientists at Harvard, UC Berkeley and other major research universities. Eventually, a consensus developed around an innovative approach – using satellite images taken by the National Oceanic and Atmospheric Administration to calculate “smoke days.” 

However, this still posed challenges. These satellite images needed to be placed on ZIP codes and extracted for further analysis. Researchers at Stanford University helped us with this aspect. Even after extraction, the raw data was difficult to analyze given the intermittent nature of fires and smoke year-over-year. 

In further consultation with experts, we decided to average the exposure over five years to get a better estimate of how average smoke exposure had grown over the years. We picked our “before” and “after periods” for comparison based on analysis of CalFire data on the prevalence of destructive wildfires in California.

What can others learn from this project?

Climate change is a challenge so great that coverage of it can sometimes provoke a feeling of powerlessness and nihilism in its audience. It doesn’t need to be this way. There are steps officials at every level can take to mitigate the wildfire threat climate change poses — saving lives and property, and enabling society to adjust to a world where hotter, drier conditions are the new normal. 

Dangerous Air offers journalists a lesson on how to radically harness open government data to report on climate change. Our partnership with academic institutions like Stanford University, expands the possibilities of what journalists can do to deeply report and investigate with data. Using methodologies rooted in sound science and research that are then distilled to the public through radio and interactive digital media, this work is an example of making research and reporting on climate change more accessible and engaging for the general public. In merging different open datasets to form connections that previously went unreported, we offer journalists an opportunity to creatively think about how they can use their experience and grassroots knowledge of issues to expand on the possibilities of data analysis in a way that resonates meaningfully for local audiences.

On the heels of the worst fire season in the state’s history,  California’s public radio stations banded together and set out a deliberate, coordinated strategy to hold powerful interests accountable for making our lives better.

This collaborative approach based on analysis of open data, academic partnerships, and training is one that can be used to confront many challenges that uniquely vex local communities while impacting the nation as a whole.

Project links:




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