September 21, 2026
Wildfire | September 21, 2026 | 2 min read
Not all fine particle pollution may be equal. Two new studies from Mount Sinai researchers suggest that PM2.5 from wildfire smoke may be more harmful than the same amount of fine particles from traffic, industry, and other sources. The findings add weight to a growing concern: smoke doesn't stay near the fire, and communities far from any flames can end up breathing it.
Both studies were led by Min Zhang, PhD, with Yaguang Wei, PhD, as senior author. The first, published in The Lancet Oncology on September 15, 2026, followed 414,016 adults aged 65 and older with lung cancer. Wildfire smoke made up about 4% of their total PM2.5 exposure but was tied to about 17% of PM2.5-related deaths. (Mount Sinai)
The second, published in Nature Communications on September 17, looked at more than 57 million cardiovascular and about 33 million respiratory hospitalizations across 20 states from 2006 to 2019. At the same concentration, wildfire PM2.5 was linked to larger increases in hospitalizations for conditions like heart failure, asthma, and COPD than PM2.5 from other sources.
The researchers don't know yet. Wildfire smoke is a complex mix of fine particles and gases, and its makeup changes depending on what's burning. Their next step is to pin down which chemical components drive the stronger effects.
"Wildfire smoke is no longer a regional environmental issue. It is becoming a nationwide public health challenge," Wei said.
The studies point to people with lung cancer and chronic heart or lung disease. The hospitalization study also found disproportionate impacts on racial and ethnic minority groups, people in metropolitan areas, and communities with lower education levels and higher economic hardship.
"For people with lung cancer or chronic heart and lung diseases, monitoring air quality and limiting exposure during smoke events may be especially important," Wei said.
No. An HVAC filter captures particles by size, not by where they came from. The EPA recommends an HVAC filter rated MERV 13 or higher to remove fine particles from smoke in indoor air, along with keeping windows closed and shutting the fresh air intake on your system if it has one. For a closer look at how ratings compare, see our guide to MERV 13 vs. HEPA for wildfire smoke.
One honest limit: filters capture particles, not smoke gases, and they aren't a substitute for medical advice. If you or someone in your home has a heart or lung condition, follow your doctor's guidance on smoke days.
Have your smoke-day filter ready before you need it
The worst time to shop for a filter is the day the air quality alert goes out. Order a MERV 13 filter in your system's size now and store it with the rest of your smoke-season supplies, so the swap takes minutes when the AQI climbs.
Two quick checks before smoke season: confirm your system can handle a MERV 13 filter (your HVAC manual or technician can tell you), and make sure the filter sits snug in its slot with no gaps around the edges. Air that slips around a filter doesn't get filtered.
Don't forget to buy your MERV 13 filters from Filterbuy