During the summer of 2023, the northeastern United States, particularly the densely populated New York/New Jersey metropolitan area, experienced a significant environmental event: the arrival of wildfire particulate matter (WFPM) from extensive Canadian forest fires.
A recent study published in Communications Earth & Environment delves into the multifaceted impacts of this incident, revealing complex interactions between atmospheric conditions, urban infrastructure, and public health.1
What is Wildfire Particulate Matter (WFPM)?
Wildfire Particulate Matter (WFPM) refers to the complex mix of tiny airborne particles released during the burning of plants and other organic materials in wildfires. These particles are predominantly carbon-based – known as carbonaceous aerosols – and include black carbon (BC), organic carbon (OC), and brown carbon (BrC) which has light-absorbing properties that can affect both climate and visibility.2
WFPM isn’t just soot or ash – it’s a chemically diverse mix that includes a wide range of organic compounds. Many of the items are still not fully identified by scientists but we do know WFPM often contains harmful substances like polycyclic aromatic hydrocarbons (PAHs), dioxins, and furans – compounds known to cause respiratory inflammation, cellular damage, and even cancer. These toxic chemicals tend to adsorb onto the particle surfaces, making WFPM especially hazardous when inhaled.
Because these particles are so small – often less than 2.5 micrometers in diameter (PM2.5) – they can penetrate deep into the lungs and even enter the bloodstream, posing serious health risks, especially for children, the elderly, and individuals with preexisting respiratory or cardiovascular conditions.
The 2023 Canadian Wildfires and Their Far-Reaching Effects
During the summer of 2023, Canada faced unprecedented wildfires, burning 66,000+ square kilometers (25,000+ square miles) of land. The smoke and particulate matter from these fires didn’t remain confined to Canada; atmospheric currents transported them hundreds of miles southward, enveloping cities like New York and Newark in a dense, orangey-brown haze. In addition to being historic and shocking, this transboundary pollution event provided researchers with a unique opportunity to study the effects of WFPM on urban environments.
Radiative Cooling: A Double-Edged Sword
One of the study’s key findings was the significant radiative cooling effect caused by the WFPM. This cooling is tied to a concept called radiative forcing, which refers to the change in the balance between incoming energy from the sun and outgoing energy radiated back into space. It’s measured in watts per square meter (W/m²).
When the value is positive, it means the Earth is retaining more heat – leading to warming. When it’s negative, as in this case (about -352.4 W/m²), it indicates that more solar energy is being reflected or blocked from reaching the ground, resulting in a cooling effect.
WFPM, especially the carbon-based particles like black carbon and brown carbon, can absorb and scatter sunlight. In the 2023 event, the dense haze from the Canadian wildfires reflected enough solar radiation to cause a ground-level temperature drop of around 3°C (5.4°F) in the New York/New Jersey metropolitan area.
On the surface, this cooling might seem like a temporary reprieve from summer heat – but it’s not without consequence.
This cooling suppresses natural atmospheric convection – the vertical mixing of air – which is crucial for dispersing pollutants. In urban environments, this stagnation can trap dangerous pollutants closer to the ground, creating persistent exposure conditions that elevate health risks for city dwellers. The haze also lingers longer when air movement is minimal, extending the duration of poor air quality events.
In short, while radiative cooling from WFPM temporarily lowers temperatures, it can worsen overall air quality, increase human exposure to toxic particles, and place additional stress on vulnerable populations.
Health Implications of Wildfire Particulate Matter
Exposure to WFPM has been linked to a range of health issues. Respiratory problems, such as asthma exacerbations and decreased lung function, are among the immediate concerns. Cardiovascular effects, including increased risk of heart attacks and strokes, have also been associated with prolonged exposure to fine particulate matter (PM2.5). Additionally, emerging research suggests potential neurological impacts like increased risk of Dementia.
The 2023 event underscored the vulnerability of urban populations to distant environmental disturbances. Cities like New York, with their dense populations and infrastructure, face unique challenges in mitigating and responding to such transboundary pollution events.
How to Protect Yourself from Wildfire Particulate Matter
When wildfire smoke blankets your area or 1,000 miles away, it’s more than just a nuisance – it’s a serious health threat, especially due to the ultrafine particles and toxic compounds in Wildfire Particulate Matter (WFPM). Here are some key steps you can take to protect yourself and your loved ones during air quality emergencies:
Stay Informed: Monitor your local Air Quality Index (AQI) through trusted sources like AirNow.gov or weather apps. Pay special attention when AQI levels exceed 100 (unhealthy for sensitive groups) or 300 (hazardous for everyone).
Stay Indoors When Possible: Limit outdoor activity, especially during peak smoke events. Vulnerable individuals– children, seniors, pregnant people, and those with respiratory or cardiac conditions – should take extra precautions.
Seal Your Indoor Environment: Close windows and doors. Use weather stripping and door draft stoppers to reduce smoke infiltration. Turn off any HVAC systems that draw in outside air unless they have strong filtration capabilities.
Wear a Mask Outdoors When Needed: If you must be outside, wear a properly fitted N95 or KN95 mask, which can significantly reduce inhalation of hazardous particles. Cloth masks and standard surgical masks do not offer the same protection from WFPM.
Use a High-Performance Air Purifier Indoors: Invest in an air purifier capable of removing both particles and gases. The Austin Air HealthMate Plus is designed for wildfire events, featuring a medical-grade HEPA filter for fine particulates and a powerful activated carbon blend to capture VOCs and chemicals like benzene, formaldehyde, and PAHs found in wildfire smoke.
Create a Clean Room: Designate a room in your home to be the clean air space – ideally one with few windows and doors. Run your air purifier continuously in that space to maintain a protective indoor environment.
What’s Next?
The 2023 Canadian wildfires were more than a regional disaster – they were a global wake-up call. With smoke traveling thousands of miles and plunging cities like New York and Newark into historically hazardous air conditions, the far-reaching consequences of wildfire particulate matter became impossible to ignore, especially in light of the temperature cooling impacts of WFPM.
Understanding how WFPM affects our health, climate, and daily lives is the first step in mitigating its impact. But beyond awareness, action is essential. From staying indoors and monitoring AQI, to equipping your home with a high-efficiency air purifier like the Austin Air HealthMate Plus, preparation can make all the difference during an air quality emergency.
As wildfires become a more frequent part of our environmental reality, clean indoor air should no longer be considered a luxury – it’s a vital layer of protection. Safeguarding your air means safeguarding your health.
REFERENCES
1 Kelesidis GA, Moularas C, Parhizkar H, et al. (2025 April 21). Radiative cooling in New York/New Jersey metropolitan areas by wildfire particulate matter emitted from the Canadian wildfires of 2023. Commun Earth Environ 6, 304. doi: 10.1038/s43247-025-02214-3.
2 The carbonaceous aerosol—a remaining challenge. (2017 November 27). World Meteorological Organization. https://wmo.int/media/magazine-article/carbonaceous-aerosol-remaining-challenge.
