Wildfires: Air Quality & Impact

As many parts of the U.S. experience sustained high temperatures and humidity, and wildfire smoke waves approach, we wanted to share a few resources with you.

• New York’s DEC presents a strong forecast. Check out the Air Quality Index for today and tomorrow: https://appfactory.dec.ny.gov/AQI/. You will note:
  • Smoke is forecast for Wednesday July 15 to bring parts of NYS into Orange AQI (unhealthy for sensitive groups).
• Take a peek at U.S. EPA’s real-time measures of air quality related to wildfire and smoke: https://fire.airnow.gov/Watch.
  • Check out the Real-Time Air Quality Index (across the U.S.) to inform activities, including for sensitive populations.
• To learn more about Wildfire Smoke and Air Quality, including how to interpret the Air Quality Index, what to do when, and which populations are more at risk, check out our Wildfire Smoke + Air Quality Toolkit.
• Finally, our Extreme Heat Toolkit compiles resources to help you prepare, plan, and protect health.

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SMOKE NOT A PROBLEM FOR VEGETABLES

Canadian wildfires are once again impacting air quality here in the Northeast. Smoke has filled the sky and warnings issued for outdoor activities. This is making many growers and gardeners worried about the potential impact the smoke will have on field grown vegetables. The good news is the impact should be minimal at worst.

Smoke-filled skies decrease sunlight and reduce photosynthesis, but to a small degree and temporarily. Despite the shade, there is still enough diffused light penetrating the smoke to maintain growth. Smoke typically does not block the pores in the leaf (stomata) where photosynthesis happens. The most important thing you can do is maintain good soil moisture by optimizing irrigation. This will keep the pores open and clean.

Concerns that leafy greens and other commodities will pick up a smoky flavor are unwarranted. Research done in California after wildfires there showed leafy greens had no issues with flavor or possible volatile chemicals on or within the leaves. The smoke we’re seeing does not contain dangerous chemicals.

The smoke we are experiencing is nearly 100% from burning forests — not plastics, buildings or chemicals. The rain that falls through this smoky layer is also not dangerous to plants, people, or animals. Unlike acid rain that forms from the burning of high sulfur fuels, the rain will be near neutral pH or just slightly acid.

Pollinators will likely stay close to their hives when it’s smoky. That’s a problem for pollination of squash, cucumbers, pumpkins and other fruiting crops. But the smoky conditions should improve in a few days, so the long-term impact is unlikely. Bees will become active again as soon as the smoke clears.

You may notice a bit of burning/spotting/bronzing on leaves, looking a bit like mite damage.This is a symptom of ozone injury that can be made worse by contaminants in smoke.It is caused by the reaction between sunlight and air containing hydrocarbons and nitrogen oxides.We often see this in midsummer when stagnant air and high temperatures cause the problem.Ground-level ozone greater than 60 PPB can cause damage. Plants will recover from this damage as new leaves should be fine.

Mask up when you’re outside tending to your plants, as the smoke is a bigger danger to you and me. But the vegetables should be fine. Keep them well-watered, and you should be enjoying a normal harvest later this summer.

- Steve Reiners, Professor Emeritus in Horticulture, Cornell University, Cornell AgriTech