What are some of the largest wildfires in U.S. history? How might smoke from wildfires impact your health? How can you help your city create a community wildfire protection plan? You will find science-based answers to those questions and more in these 10 Wildfire FAQs. We’re also providing links to additional resources that can help you prepare for and protect yourself against threats from wildfire and wildfire smoke.

1) What health problems does smoke from wildfires cause?

Smoke from wildfires has been linked to respiratory issues such as asthma attacks, bronchitis, and heart disease. People who are elderly, pregnant, or have chronic lung or heart issues are especially susceptible to health problems from wildfires.

Smoke is made up of a complex mixture of gasses, vapors and fine particles (i.e., soot) produced when wood and other organic matter burn. Among the substances found are gasses from partially burned hydrocarbons (e.g., carbon monoxide) and potentially toxic or irritant volatile organic compounds (e.g., acrolein, formaldehyde). All of these constituents can potentially result in adverse health effects. The National Institute of Environmental Health Sciences estimates that wildfire smoke causes approximately 200 deaths and over 400,000 emergency room visits in the U.S. every year.

From a public health perspective, airborne particulate matter is the primary pollutant of concern over a short-term exposure period (e.g., days to weeks). Particularly, fine particles such as PM2.5 (particles with diameters that are 2.5 micrometers and smaller), which can get into your eyes and respiratory system and can cause health problems such as burning eyes, runny nose, bronchitis and asthma. To monitor the air quality from wildfire smoke, check reports generated at airnow.gov or other local and state air quality management districts.

2) What are some of the largest wildfires in U.S. history?

The size of the wildfire does not necessarily coincide with the amount of property damage or the number of human lives lost due to the fire. California’s Camp Fire (2018) reached just 153,000 acres in size, but destroyed almost 19,000 structures and took 86 lives. Damages reached approximately $16.5 billion.

In terms of size, here are the 10 of the largest wildfires in the United States in this century as compiled by a state-by-state search of wildfire statistics:

  1. 1.3 million acres: Alaska’s Taylor Complex Fire (2004) was caused by lightning
  2. 1 million acres: California’s August Complex Fire (2020) was caused by lightning
  3. 650,000 acres: Idaho’s Murphy Complex Fire (2007) was caused by lightning
  4. 564,000 acres: Georgia’s Big Turnaround Fire (2007) was caused by a downed powerline
  5. 535,000 acres: Arizona’s Wallow Fire (2011) was caused by an unattended campfire
  6. 500,00 acres: Oregon’s Biscuit Fire (2002) was caused by lightning.
  7. 468,600 acres: Arizona’s Rodeo–Chediski Fire (2002) was caused by arson (Rodeo) and a signal fire (Chediski)
  8. 459,000 acres: California’s Mendocino Complex Fire (2018) was ignited by sparks from a hammer
  9. 400,000 acres: Kansas suffered most of the damage from the Anderson Creek Fire (2016). The fire began in Oklahoma, and the origin is unknown.
  10. 363,000 acres: Utah’s Milford Flat Fire (2007) was started by lightning. 

The largest wildfire in U.S. history occurred in Wisconsin (1871). The Peshtigo Fire burned as much as 1.5 million acres and killed over 1,200 people. The fire is believed to have been started by a crew of railroad workers.

3) How does wildfire affect the environment?

Wildfires can occur without notice and spread rapidly, consuming trees, grasses, shrubs, and other plant life, causing massive amounts of smoke to spread into the atmosphere and can cause significant impact to air quality and the environment. 

Wildfires cause changes in vegetation and soil quality, as well as water availability. Effect on the environment can be severe.

Wildfire events release large amounts of smoke into the atmosphere, which can travel hundreds of miles. Wildfire smoke is made up of a complex mixture of gasses, vapors and fine particles (i.e., soot). During wildfire events, massive amounts of carbon dioxide (CO2), a greenhouse gas, is released into the atmosphere.

However, there is a positive side to wildfires. Wildfires are a necessary part of our ecosystem’s renewal and regeneration process. Forest fires can clear away debris, kill diseases and harmful insects, serve as a natural fertilizer for soil, spread seeds, and create new feeding opportunities for wildlife when new plants begin to sprout in the affected area.

4) What are some notable wildfire statistics?

Between 2008 and 2015, there were 120,417 wildfires reported in the United States. These fires resulted in an average of 2,031 injuries and 692 deaths per year. Every year, over 100 million acres of forest burn in the United States. 

Here are notable U.S. wildfire statistics for 2017-2021:

  • 2021: 52,729 wildfires burned 6.6 million acres 
  • 2020: 58,590 wildfires burned 10.1 million acres
  • 2019: 50,477 wildfires burned 4.7 million acres
  • 2018: 58,083 wildfires burned 8.8 million acres
  • 2017: 71,499 wildfires burned 10 million acres

How severe will the coming fire season be? The degree of drought is an indicator, but nobody knows when or where wildfires will break out. What we do know is that we can expect more than 50,000 fires and see millions of more acres in flames. 

5) How big is a smoke particle?

The particulate matter that makes up wildfire smoke includes a wide range of sizes.  Particulates form during combustion, as well as other chemical reactions that occur during a wildfire event. The size of these particles varies depending on their source. For example, cigarette smoke contains primarily very large particles, whereas volcanic ash has smaller ones. How big is a smoke particle? That depends on the type of particle.

Particles from wildland fires vary in size, but about 90 percent of the particles are PM2.5 (.0025mm). PM2.5 are defined as particles with diameters that are 2.5 micrometers and smaller. PM 2.5 particles are capable of penetrating deeply into the lungs and contributing to serious health problems. To put the size into perspective, a typical human hair is around 70 microns (0.07mm) wide. In comparison, a grain of sand is around 2mm wide.

6) Is fire emergency planning important even if I don’t live or work near forests? 

Wildfires are common in the U.S., especially during the summer months. Wildfires can cause significant damage to property and threaten lives. If you live in an area where wildfires are likely to occur, you should prepare for them by creating a fire emergency plan in advance of the next event. Most often, wildfires occur without warning. You should have a plan for evacuation and know how you will respond to a wildfire whether you shelter in place or need to go elsewhere.

Even if you don’t live or work near forested areas, you can still be negatively impacted from wildfire smoke. Loss of power can also be an issue. In 2019, for instance, hundreds of thousands of California residents were without electricity on several occasions. Don’t gamble on wildfire. Get and stay prepared by conducting fire emergency planning. 

7) What wildfire regulations does a business need to consider? 

Building codes and regulations exist to keep public safety at the forefront of everyone’s minds, and it is important to follow these procedures in order to keep people safe. 

Since laws regarding wildfire vary according to region, check with local authorities to determine the wildfire regulations for business that apply to your location. For reference, check the Cal OSHA wildfire smoke standards.

Fires that destroy retail stores usually occur in rural areas where there is little development. These fires often cause extensive damage because the business failed to establish a wildfire emergency plan in advance. They may also lack insurance coverage for their buildings. In addition, many retailers sell products that are flammable such as gasoline, paint thinner, kerosene, etc. This makes them particularly susceptible to the effects of a wildfire.

Firefighters know that commercial structures burn faster and hotter than residential buildings. Many large-scale fires start on roofs or other high points within these buildings. The heat generated by this type of fire can be intense enough to melt steel beams. Here again, advanced planning for wildfires is essential.

8) Do some cities create a community wildfire protection plan? 

A community wildfire protection plan (CWPP) is a comprehensive approach to prevent or reduce the impact of wildfire. This plan helps communities identify their risks, develop strategies and implement them. If your community has yet to develop a CWPP, urge your local government and civic groups to consider doing so.

The need to understand and address the problem of wildfires is one that is increasingly important due to the increasing exposure of communities and their property, as well as the long-term effects on the environment.

9) What is the best air purifier for wildfire smoke? 

According to the American Lung Association, wildfires emit particulate matter that can remain suspended in the air for days. Air purifiers (also known as portable air cleaners) are designed to filter the air, which can help reduce the negative impact on indoor air quality as well as provide protection for indoor pets.

There are several types of air purifiers, each designed to filter specific pollutants from the air. Some are effective at removing particulate matter (e.g., PM2.5), while others are good at removing gasses and odors.

Using an air purifier in your home or business can reduce fine particle pollution (PM2.5) which is the primary contaminant of concern during a wildfire and one of the most common causes of respiratory diseases. While we have no particular brand recommendations, do choose units that can filter PM2.5 particles. You can also check the CADR rating to determine the area the equipment you are using will service, although not all air purifiers will display that information.

10) How can I get help with wildfire preparation planning?

Wildfires are a serious concern for many homeowners, especially in areas where these devastating events happen frequently. If you live in an area that is at risk for wildfires, you should take time to conduct wildfire preparation planning. Communities are at risk of potentially devastating impact by these fires. 

In order to get ready for a wildfire, you should get educated on what to do before, during, and after a wildfire starts. Ask officials from your local government about what fire risk assessments have been taken. That knowledge will help increase your understanding of how prepared you are for a potential fire. 


If you need assistance with developing a wildfire preparation plan for your business or community, call FACS at (888) 711-9998. Our smoke and fire experts can help you establish a wildfire preparation plan that is both actionable and effective.