Smoke whether from wildfires, bonfires, or even prolonged cigarette use, can definitely harm outdoor and indoor plants by impacting their growth, health, and survival. Several gases commonly found in smoke have detrimental effects on plants.
Sulfur Dioxide (SO2) is a gas that is often produced by burning fossil fuels or organic matter, is highly damaging. Plants absorb SO2 through their small pores on their leaves where it can disrupt chlorophyll and enzyme production. Nitrogen Oxides (NOx) is similar to SO2 gases and can also damage plant tissues and impair photosynthesis. Nitrogen oxides contribute to the formation of acid rain, which acidifies the soil and harms plant roots.
Carbon Monoxide (CO) is consumed by plants for photosynthesis, high concentrations can be toxic when they interfere with cellular respiration and nutrient uptake. Ozone (O3) at ground level is formed by chemical reactions involving pollutants in sunlight that harms plants. It degrades chlorophyll, reduces photosynthesis processes. Volatile Organic Compounds (VOCs) in smoke act as phytotoxins that are directly poisonous to plants. They disrupt cell membranes and interfere with plant hormone production.
Beyond gases, wildfire smoke carries tiny solid particles like soot and ash, also known as particulate matter. When these particles physically coat plant surfaces, they create barriers that hinder vital functions. Photosynthesis is significantly reduced when coated plants aren’t able to absorb sunlight effectively. Larger ash particles and embers can cause physical abrasion and damage delicate leaf surfaces.
Raju Soolanayakanahally, a researcher with Agriculture and Agri-Food Canada in Saskatoon, said smoke dries out the atmosphere, making plants think they’re experiencing drought. As a result, they close their stomata which are tiny pores on the surface of their leaves that keep water stored, instead of releasing it into the atmosphere. Soolanayakanahally said that can impact plant growth. “Even a simple 30-minute exposure to smoke can reduce photosynthesis by almost 50 per cent,” he said.
When the impacts of wildfire smoke deposits hamper the photosynthesis processes of plants, they develop signs of blocked growth, weakened structure, reduced flowering and fruiting. This makes them more susceptible to other environmental stresses, diseases or pest infestations. Visible signs of smoke damage are leaves that turn brown or black as the cells die due to chemical injury. Bleached or discoloured spots can appear and in severe cases, plants may shed their leaves prematurely.
While much of the direct impacts of wildfire smoke deposits are on the leaves and stems of plants, smoke can also indirectly affect the soil and roots. Sulphur dioxide lowers the soil’s pH, making essential nutrients less available to plants and potentially releasing toxic metals. This is a concern for long-term exposure. Heavy ash deposition can alter soil structure, potentially leading to poor drainage or aeration, which can affect root health.
If plants are covered with smoke and ash, both sides of their leaves should be cleaned with water. As for garden produce, simple washing with water before consumption should remove any of the residues. In conclusion, the good news is if plants are thoroughly washed down with water after wildfire smoke is gone, they will most likely suffer little or no harm. The bad news is that the wildfire smoke is still hazardous to humans.
.