Atmospheric chemist Manvendra Dubey has been at Los Alamos National Laboratory for 24 years. He is a Laboratory Fellow and chair of the Fellows Committee. Photo Courtesy LANL
Smoke during the recent Medio Fire was studied at the LANL Center for Aerosol-Gas Forensics (CAFÉ) by Manvendra Dubey and the team. Photo Courtesy LANL
Instrumentation at the LANL Center for Aerosol-Gas Forensics (CAFÉ) includes a Soot Particle Time of Flight Spectrometer and an aerosol aging chamber as well as various optical, microphysical and water uptake instruments. Photo Courtesy LANL
BY MAIRE O’NEILL
When experts in atmospheric chemistry, climate and meteorology weighed in at a Sept. 23-25 National Academy of Science, Engineering and Medicine virtual workshop on improving understanding and forecasting of the air quality impacts of wildland fires, Los Alamos National Laboratory’s Manvendra Dubey was there to contribute to the discussion.
Dubey, an atmospheric chemist, has been at LANL for 24 years. He is a Laboratory Fellow and chair of the Fellows Committee.
“I run a small but tight team that looks at both smoke and aerosol greenhouse gases for climate, energy and air quality and make sure we are all safe. I’m an experimentalist by training and my goal is to improve models,” Dubey told the Los Alamos Reporter in a phone interview.
He did his undergraduate work in India and noted that many of his professors were Indians who had earned their PhDs in the United States and returned to India and that he was inspired by many of their careers.
“I came and did my graduate school at Harvard University. I studied the stratospheric ozone that was happening at that time and then I moved to SRI International and worked with Lawrence Livermore National Laboratory on the stratospheric ozone impact of supersonic aircraft and I’ve been at LANL since then. It’s fair to say my career has mostly been built around LANL,” he said.
As scientists everywhere look at how wildfires are expected to change in the next decade due to climate change, Dubey said they get better every year and every decade at understanding and measuring what they do.
“And as we do that, policy follows,” he said. “For example, smoke is not regulated but air quality is. If forest fires were a commercial activity – meaning if you were doing open biomass burning – it would be regulated. But fires aren’t regulated – they’re natural innate emissions,” he said.
The Environmental Protection and others look at particulate matter below 2.5 microns as a measure of exposure. The reason they use 2.5 microns is because it can penetrate your respiration system and go to the lungs, Dubey said. Scientists are studying smoke from wildland fires, fires that move from wildland to urban areas, prescribed burns and agricultural fires. They are looking at what could be toxic in wildland fire smoke particularly in light of the exposure of people in California, Oregon and Colorado to large fires.
“While forests burn to produce mostly carbon dioxide and water, they also produce smaller amounts of gases like carbon monoxide and even smaller amount of organics like formaldehyde and methanol that are known to be toxic,”Dubey said. “Finally, what we really see and smell are the fine particles or aerosols in smoke that are also toxic as they get through our respiratory system causing damage to our health (such as asthma) and are regulated by the EPA. Fires also can produce and mobilize metals in the particle or gas phase – like mercury – that can be a concern.”
Smoke at the surface is what causes human health problems while smoke at higher altitudes allows it to move farther away and cause health problem there if it gets to the surface Dubey said. This longer range transport also has consequences to weather and climate as it can reduce sunlight at surface and scatter or absorb sunlight depending on how dark or sooty it is.
“Generally early in a wildfire the forest burns fast and quick – this flaming phase produces a large amounts of dark soot (20%) can be seen as dark rising plumes that are lofted high and amenable to long-range transport. Later as the fire is controlled, the lower temperature result in smoldering, less-hot fires that emit white organic-rich smoke that is white,” he said. “At these temperatures more organic compounds are emitted and the toxicity of smoke is larger. The smoke also smolders at night as temperatures are cooler and also as the boundary layer is capped it results in accumulation and increased exposure to nearby communities”.
Smoke that is transported over longer distances, such as the smoke seen in the Los Alamos area in the last few months, gets mixed with cleaner air and the dilution reduces the concentration relative to the source region, Dubey said, however, more people can be affected. In addition studies are showing that as the smoke ages it gets more oxidized and those particles can be more toxic to humans. He noted that much more research is needed to look at the tradeoffs between chemistry and particle concentrations (PM2.5) with the latter being the principal regulatory tool to assess damage.
How do scientists measure the characteristics or composition of smoke?
“We use research-grade instruments such as spectrometers that use lasers to mimic sunlight to measure their particle size and optical properties as well as the composition of the gases like carbon monoxide, formaldehyde, carbon dioxide, methane, ethane and nitrous oxide,” Dubey said. “We also measure soot using a laser-induced incandescence (the black soot absorbs the laser heat, and glows). We use an aerosol mass spectrometer to measure the composition of the smoke including metals that can be a health hazard.”
At LANL, scientists have a reactor with a lamp that mimics sunlight, Dubey said.
“It also has oxidants like ozone and water so you can basically mimic what’s happening in the air, in the atmosphere with the sunlight in a more controlled environment and control them and scan them usually at much higher concentrations. This allows us to more repeatable science and what we learn can basically be incorporated into models,” he said.
Scientists are also paying attention to smoke from urban fires.
“When you burn cars and buildings and metals, you get a lot of things like aluminum and hydrochloric acid, but the amount of information available on these urban materials is much less than wood burning in fires. We are very concerned about these ‘urban fuels’ as we call them. That’s something we know a lot less about than forest fires and they’re both very complex,” Dubey said. “We’re actually looking at that for many facets. For example, war fighters are also exposed because in a battlefield we also have fires. It’s nice we match our science with our mission to make sure our military is also safe as they keep our world safer.”
Dubey said LANL is very proactive studying fire and climate having experienced two very large fires, Las Conchas and Cerro Grande, in the last 20 years. The Lab’s Center for Aerosol-Gas Forensics (CAFÉ) has about a dozen scientists on the team that conducts field observations, records laboratory measurements, and works on modeling and simulations. The Center has acquired a Soot Particle Time of Flight Spectrometer and an aerosol aging chamber as well as various optical, microphysical and water uptake instruments.
The CAFÉ’s work is only beginning as health and smoke has become a huge topic. Dubey noted that at the National Academy meeting, he learned that that smoke from Oregon last month reached Washington, DC.
“They had the highest ever recorded amount of black powder. That day the number of COVID cases went up. What happened? Were more people going to the doctor to get checked because of smoke or is there correlation between the two? Those are the kinds of things that we discuss,” he said.
With the impact of fires being felt far afield, increased risks to human health are being posed and Dubey and his team will continue to investigate ways to cope with air quality and other impacts of wildfires as they study the makeup and movement of smoke.