Wildfire Smoke and Asthma Emergency Visits in New York, June 2023

From June 6 to 8, 2023, smoke from wildfires in eastern Canada brought poor air quality across New York, driven by fine particulate matter (PM2.5). The air quality index reached "unhealthy" or "very unhealthy" levels statewide. PM2.5 from wildfire smoke is linked to more medical emergencies, including asthma attacks, and New York's health department, with CDC, measured what happened.

How it was measured

The state Department of Environmental Conservation's air monitors — one in each of eight regions — supplied hourly PM2.5 readings from June 1 to 14, compared against a 10-year June baseline (2013–2022). Asthma-related emergency department (ED) visits came from the state's syndromic surveillance system, which covers all 134 EDs in New York outside New York City (the city was not included).

The smoke

PM2.5 peaked on June 7 everywhere except the Adirondacks, where it peaked a day earlier. Daily averages that day ranged from 55.2 µg/m³ in the Western region, 590% above its baseline of 8.0, to 122.3 µg/m³ in the NYC metro region (measured in Westchester County), 1,229% above its baseline of 9.2.

The asthma visits

There were 1,310 asthma-related ED visits over June 1–14. On June 7, visits statewide jumped 81.9% above the June 1–5 average, from 80.8 to 147 a day, and rose at least 35.4% in every region except the Adirondacks, where they fell slightly (from 2.4 to 2). Across the regions other than the Adirondacks, daily PM2.5 and asthma visits moved together, with correlations from 0.31 (Western) to 0.80 (Central).

The largest increases came in:

By age, statewide visits on June 7 rose:

• 197.6% among people aged 10–29 (16.8 → 50.0);
• 77.1% at 30–49 (19.2 → 34.0);
• 89.0% at 50–69 (16.4 → 31.0);
• 76.5% at 70 and older (6.8 → 12.0);

but fell 7.4% among children aged 0–9 (21.6 → 20.0).

Daily mean PM2.5 and asthma-related ED visits, statewide and in selected regions, New York excluding New York City, June 1–14, 2023. CDC, MMWR.

What it means

The near-real-time regional data supported the state's response, including advice to limit outdoor activity. As wildfire smoke events become more frequent and widespread, findings like these can sharpen warnings and focus help on people at higher risk of asthma attacks. Children and non-Hispanic Black people disproportionately need emergency care for asthma, and extreme weather may widen those inequities, so responses should prioritize reaching them — for example, by working with physicians to warn patients with asthma about smoke, and with schools on wildfire smoke plans.

The analysis had limits: one monitor stood for each whole region, asthma attacks may be underreported, and there was little data on other factors.

Sources

• Meek HC, Aydin-Ghormoz H, Bush K, et al. "Notes from the Field: Asthma-Associated Emergency Department Visits During a Wildfire Smoke Event — New York, June 2023." MMWR 72(34). CDC.