Matthew Botill (California Air Resources Board)

This week, we caught up with Matthew Botill, Chief of Climate Investments at the California Air Resources Board, about CARB’s perspective on the wildfire crisis.

Matthew Botill, Chief Investment Officer at CARB

This week, we caught up with Matthew Botill, Chief of Climate Investments at the California Air Resources Board, about CARB’s perspective on the wildfire crisis. CARB is charged with protecting the public from the harmful effects of air pollution and developing programs and actions to fight climate change. The “clean air agency” of California is working towards better understanding the rise and impacts of wildfires as well as devising innovative policy-oriented solutions.

How is CARB addressing wildfires?

  • We track and report air quality impacts from wildfires. CARB supports air districts in monitoring smoke from wildfires, including particulate matter, which is the pollutant from wildfires primarily responsible for the poor air quality we’re seeing across California and the West Coast. California has a network of over 250 permanent air monitoring stations, operated by federal, State, and local agencies, as well as a number of portable monitors that can be deployed as part of the incident air monitoring program. This monitoring data is used in many of the air quality reporting services, like AirNow, that people are using to understand their local air quality and the real-time impacts from wildfires.
  • We estimate GHG and criteria pollutant emissions from wildfires. CARB is also responsible for developing an ecosystem carbon inventory for natural and working lands. This inventory quantifies the carbon stored in the State’s forests, soils, and other natural lands. Looking year-over-year at the data in the inventory, we can see clear trends of carbon-loss in California’s natural and working lands from wildfire and other disturbances
  • We conduct research on the effects of wildfire on California, specifically focused on improving our understanding of the air pollution components, regional/local air quality impacts, health impacts, and other effects of wildfires.
  • We work with our sister agencies on strategies to reduce wildfire emissions. The California Natural Resources Agency (CNRA), and its boards and departments, is the State agency primarily responsible for taking actions to reduce wildfire risk and severity.  ARB staff work closely with CNRA in a number of ways:
  • Through our California Climate Investments (CCI) program, we work with CNRA to identify forest management strategies that improve forest health, lead to long-term carbon sequestration, and reduce the risk of wildfire. We work with CNRA to assess the GHG benefits from these actions. Some of the projects funded through the CCI program include land conservation and management, fuels reduction, prescribed fire, advanced technology biomass utilization, support for alternative wood products from forest residue, and others.
  • Through policy-coordination and technical coordination on forest carbon accounting.
  • By working with land managers and air districts to increase opportunities for prescribed fire, which is an important forest management tool.
  • We work to mitigate the effects of wildfire by supporting and encouraging prescribed burning across the state, when feasible. With recent bills and Executive Orders signed, the amount of prescribed fire will be increasing. CARB staff forecast when weather conditions are favorable for prescribed fire for much of the state. We also work closely with air districts and land managers to ensure more prescribed fire is occurring. Lastly, we are working on effective messaging to promote the benefits of prescribed burning emissions when compared to wildfire emissions.

What makes this year different from the past years of wildfires from an air quality perspective?

As of September 23, 2020, over 3.6 million acres had been burned by nearly 8,000 wildfires in the state (, which is nearly double the previous high of 1.975 million acres in 2018, and the fire season is not over. Although previous years have exhibited a significant degradation in air quality resulting from wildfire smoke, what makes 2020 different from previous years is the unprecedented levels of PM2.5 in the atmosphere (exceeding 600 ug/m3 in some locations) and the geographic extent and duration of the impact, with nearly the entire state experiencing some smoke impacts over the past month.

Can you put into perspective the health and environmental impacts of wildfires (in terms of GHG emissions, air pollution)?


We are still continuing to grow our knowledge, but CARB is deploying our laboratory, research, and monitoring teams to better understand the health effects of these wildfires:

  • Wildfires produce harmful complex mixtures of air pollutants, including particulate matter (PM), toxic air contaminants, and carbon monoxide (CO).
  • Smoke from structural fires, such as residential, commercial, and industrial fires, can contain dangerous toxins, including metals, CO, hydrogen cyanide and toxic VOCs (volatile organic compounds).
  • Smoke particles in soot, ash and dust can build up in our bodies and cause a number of immediate health problems even in healthy individuals, including burning eyes, runny noses, scratchy throat, irritated sinuses, and headaches. Wood smoke can cause lung irritation leading to cough and shortness of breath and the effects can be seen even after the smoke clears, although healthy people will recover more quickly.
  • Research shows a strong associations between exposure to small particulate matter (PM2.5) from wildfire smoke and increasing severity of asthma, other respiratory disease, such as COPD, inflammation or infections, including bronchitis and pneumonia, emergency department visits, and hospital admissions.
  • Long-term exposure to PM2.5 is linked to a wide range of human health effects, such respiratory and heart related illnesses and hospitalizations, adverse brain effects, depression, memory loss, learning disorders, reduced lung function growth in children and premature death. Often these effects can be seen days after the smoke exposure.


  • California’s forests cover about 1/3 of the State. Approximately 85% of terrestrial carbon is stored in forests and shrublands.
  • According to our inventory, our natural and working lands lost approx. 140 MMT of carbon between 2001 and 2014. This is equivalent to a loss of  510 MMT of CO2 that was previously sequestered in California’s lands. It’s worth noting that these emissions come from natural systems are distinctly different from emitting carbon from fossil-fuels that has been sequestered underground for millions of years. As California seeks to address changing wildfire regimes, the severity of carbon losses from wildfires will have implications for ecosystems, biodiversity, the economy, public health, and more.
  • 2018 inventory was based on existing data and is the first comprehensive carbon inventory for the state. California is investing in advancement in measuring and monitoring carbon fluxes.

Do you find that certain groups (e.g., low-income folks or minorities) are more impacted by the environmental and health consequences of wildfires than others?

Even healthy people may experience symptoms in smoky conditions or after exposure particularly those who work outdoors. However, some groups are more impacted by wildfire smoke – especially children, the elderly, pregnant women and people with heart or respiratory conditions. These sensitive groups are advised to limit outdoor activities, especially when the Air Quality Index (AQI) reaches ‘Unhealthy for Sensitive Groups.’

Elevated pollution from other sources such as high ozone in the summer and pollution from living near traffic or other industrial sources will compound the effects of wood smoke exposure. People living near high traffic and other sources are often in communities of color and are known to be more sensitive to the impacts of pollution, including particulate matter pollution.

How can we quantify the cost of health impacts of wildfires (ie. AQI)? In the short term and long term?

The impacts and health costs of the impacts of wildfire are an ongoing research concern, but it is known that short term exposure to wildfire results in increased hospitalizations and emergency room visits. The long term impacts of wildfire are still being studied. Effects in wildland firefighters have shown reduced lung function and a possible increase in hypertension.

What are areas of innovation / investment that can mitigate wildfires and its effects? What kind of projects do you focus on funding at CCI?

Right now one of the big questions that California is grappling with is how to fund/ support and maintain the large increase in forest management activities needed to reduce wildfire risk and support resilient forests with long-term carbon storage. According to CNRA, over 15 million of California’s 33 million acres of forest-land is in need of treatment through thinning, restoration, or prescribed fire.

There are plenty of opportunities for innovation/investment here. One area CARB and other State agencies are interested in is how to utilize the forest residue to produce advanced biofuels and/or hydrogen that can support California’s long-term goals to decarbonize transportation fuels and industrial energy needs. We need strategies that can economically turn forest residue into fuels or energy without the criteria and toxic emissions associated with typical biomass combustion. Anaerobic digestion, advanced gasification, and other techniques are promising from an energy/fuels standpoint. There are also opportunities to look at forest residue to create alternative wood products, like cross-laminated timber, to displace more traditional carbon-intensive materials.

Every year sets a new record for wildfires. Where do we go from here and what will the future look like?

California state agencies are working together to better understand natural carbon in a changing climate and how best to stabilize carbon in California’s ecosystems. Maximum carbon sequestration in natural and working lands is not the goal; sustainable lands are the goal (e.g. overstocked forests have high sequestration, but are not sustainable).

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