Wildfires & Air Quality

Jan 24, 2020

In recent weeks, headlines have been dominated with news of wildfires, specifically in Australia. Wildfires can create a range of air quality contaminants such as particulate matter, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), carbon monoxide, etc. In this blog, we will discuss these air quality contaminants generated by wildfires and some of the health effects associated with them.

Particulate Matter

Particulate matter simply refers to particles of solid or liquid materials in the air. Indoors, larger particles can be generated from dust or debris, while fine particles are generated from cooking, printers, combustion and infiltration from the outdoors. Fine particulate matter is considered to be particles that are 2.5 microns or smaller in size. Wildfire smoke is a combination of gases and fine particulate matter released during the combustion process of a wildfire. The particles can be comprised of black carbon, allergen fragments (mold spores/pollen), and other byproducts of the combustion. Inhalation of fine particles can cause cardiovascular and respiratory health effects. 


Volatile organic compounds, or VOCs, refer to organic substances that are not stable at room temperature or standard pressure so they become gaseous. Another way to put it: VOCs are chemicals in the air. There could be several thousand VOCs emitted during a wildfire and their composition can vary depending on the source and temperature of the fire. Exposure to elevated VOCs can cause a range of health effects depending on the types of chemicals present, the concentration, and the exposed individual’s sensitivity.


Polycyclic aromatic hydrocarbons, or PAHs, are typically semi-volatile organic compounds that contain only hydrogen and carbon. These compounds have a variety of sources – including burning organic material – and they can be cancer-causing compounds. These are the chemicals that contribute to cigarette smoke being carcinogenic. Exposure can be caused by fallen particulate matter generated from the wildfires. PAHs can also affect soil and water supplies. One study has shown that PAHs can be detected in indoor environments from the household dust caused by wildfire ash in the affected properties.

Other Contaminants

Many other air quality contaminants can be produced by wildfires. Carbon monoxide is produced from the incomplete combustion during the fire, while carbon dioxide is a byproduct of complete combustion. Carbon monoxide can replace oxygen in the blood and potentially travel quite a distance with wind patterns, which can impact air quality in other areas. Carbon dioxide can cause headaches and fatigue, along with being a contributor to climate change. VOCs, nitrogen oxides, and sometimes carbon monoxide are considered to be precursors to photochemical ozone. Ozone exposure can cause respiratory health effects.  


Wildfires can create a myriad of air quality issues in the short term, and even after the wildfires have ceased. According to NASA, the increasing intensity of climate change may increase the frequency of their occurences, due to a hotter and drier planet. The increase in frequency could cause air quality issues for residents in the vicinity of the fire, but also other areas, as the wind can transport some of the contaminants across the world. Scientists have detected smoke from the wildfire in Australia in parts of South America. While wildfires don’t commonly occur in the Chicagoland area, Indoor Science does offer post fire testing in homes and buildings that have sustained a structural fire.