Story at-a-glance -

• Nature-based solutions can compete with technology to reduce toxic air emissions across the U.S.
• Restoring natural areas to county-level average canopy cover could reduce air pollution by an average of 27%
• In 75% of the counties, nature-based solutions ended up being less expensive than technological interventions such as smokestack scrubbers in mitigating pollution
• Maintaining current levels of vegetation as well as restoring vegetation cover in industrial areas could help reduce some of the most common types of air pollutants, including sulfur dioxide, nitrogen dioxide and particulate matter
• A mycorrhizae network connects trees to each other in mind-blowing ways, such that trees might be viewed as beings with a capacity for intelligence, decision-making, learning and memory

Trees are one of nature's greatest gifts, one that could be harnessed to strategically reduce air pollution in some of the most problematic spaces, such as near factories, industrial sites, roadways and power plants. In fact, nature-based solutions can compete with technology to reduce toxic air emissions across the U.S., according to research published in the journal Environmental Science & Technology.1

What's intriguing is that existing natural areas, including forest, grassland and shrubland vegetation, are already responsible for mitigating a significant portion of U.S. air emissions, according to the study, which suggests that restoring natural land cover where possible could be a key strategy to improving air quality.

Restoring Nature Near Factories Could Reduce Air Pollution

Using data on annual emissions in U.S. counties and existing land cover, researchers from The Ohio State University revealed that restoring natural areas to county-level average canopy cover could reduce air pollution by an average of 27%. Further, in 75% of the counties, nature-based solutions ended up being less expensive than technological interventions such as smokestack scrubbers in mitigating pollution.2

Lead study author Bhavik Bakshi, professor of chemical and biomolecular engineering at The Ohio State University, said in a news release:3

" The fact is that traditionally, especially as engineers, we don't think about nature; we just focus on putting technology into everything … And so, one key finding is that we need to start looking at nature and learning from it and respecting it. There are win-win opportunities if we do — opportunities that are potentially cheaper and better environmentally."

In instances of combating air pollution from agriculture, dust emissions, power generation, metal processing, certain manufacturing plants and on-road emissions, ecosystems are less expensive than technologies. Only in the case of emissions from industrial boilers and some cases of manufacturing did pollution-control technologies win out.

Maintaining current levels of vegetation as well as restoring vegetation cover in industrial areas could help reduce some of the most common types of air pollutants, including sulfur dioxide, nitrogen dioxide and particulate matter. Further, while the study didn't look into how well different types of plants "scrubbed" the air, it's likely that certain plant species could be more effective than others.4

Both urban and rural areas stand to benefit from ecosystem-based approaches to combating air pollution. "This suggests that even though vegetation cannot fully negate the impact of emissions at all times, policies encouraging ecosystems as control measures in addition to technological solutions may promote large investments in ecological restoration and provide several societal benefits," the study noted.5

Health Hazards of Air Pollution

By mitigating air pollution, trees and other plants could save lives across the globe, as contaminated air is a leading cause of death.

Research published in The Lancet revealed that 9 million premature deaths were caused by pollution in 2015, which is 16% of deaths worldwide — "three times more deaths than from AIDS, tuberculosis and malaria combined, and 15 times more than from all wars and other forms of violence," the researchers wrote.6

Among the pollution-related deaths, the majority — 6.5 million — were caused by airborne contaminants.7 A World Health Organization (WHO) report also found that 93% of children live in areas with air pollution at levels above WHO guidelines.8

Further, more than 1 in 4 deaths among children under 5 years is related to environmental risks, including air pollution. In 2016, ambient (outside) and household air pollution contributed to respiratory tract infections that led to 543,000 deaths in children under 5.

In some areas of the world, like New Delhi, India, polluted air has reached crisis levels, with officials warning residents to stay indoors and handing out face masks to children. The air is so polluted due to agriculture and transportation that it causes burning eyes and a thick fog that makes visibility difficult.9

"Over the past days," The Atlantic reported in November 2019, "[air pollution] levels in New Delhi have exceeded 10 times what the U.S. Environmental Protection Agency deems safe. (The idea that any level is 'safe' is disputed, as even very low levels have been found to cause disease.) The effect is lethal, in India and beyond."10

While industry can certainly contribute to dangerous levels of air pollution, many are surprised to learn that the No. 1 cause of air pollution in much of the U.S., China, Russia and Europe is linked to farming and fertilizer — specifically to the nitrogen component of fertilizer used to supposedly enrich the soil and grow bigger crops.

In fact, research published in the journal Geophysical Research Letters demonstrated that in certain densely populated areas, emissions from farming far outweigh other sources of particulate matter air pollution.11

So, when considering the best types of plants to combat pollution, it's important to understand that clearing grasslands and other natural spaces to plant monocrops is part of the problem — not part of the solution.

Planting 1.2 Trillion Trees Could Save the Earth

Planting 1.2 trillion trees could be the answer to saving the Earth and would be capable of storing so much carbon dioxide (CO2) that they would cancel out a decade's worth of human-made CO2 emissions.12

The findings come from the work of ecologist Thomas Crowther and colleagues at Swiss university ETH Zurich, who also revealed that there's room for an additional 1.2 trillion trees on the planet. Writing in the journal Science, Crowther and colleagues explained:13

"We mapped the global potential tree coverage to show that 4.4 billion hectares of canopy cover could exist under the current climate.

Excluding existing trees and agricultural and urban areas, we found that there is room for an extra 0.9 billion hectares of canopy cover, which could store 205 gigatonnes of carbon in areas that would naturally support woodlands and forests. This highlights global tree restoration as one of the most effective carbon drawdown solutions to date."

Currently, the Earth is home to 3 trillion trees, which is seven times more than previously believed. "There's 400 gigatons [of carbon] now, in the 3 trillion trees, and if you were to scale that up by another trillion trees that's in the order of hundreds of gigatons captured from the atmosphere — at least 10 years of anthropogenic emissions completely wiped out," Crowther told the Independent.14

The United Nations responded to the findings, changing their Billion Tree Campaign to the Trillion Tree Campaign, which states, "Global reforestation could capture 25 percent of global annual carbon emissions and create wealth in the global south."

More than 13.6 billion trees have already been planted as part of the campaign,15 which tracks not only where trees have been planted, but also where forests currently exist and where forests could be restored. The Trillion Tree Campaign states that there is actually space for up to 600 billion mature trees on the planet, without taking space away from agricultural land.

However, since some planted trees won't survive, the target is to plant at least 1 trillion trees to reach the 600 billion mature tree goal. "Additionally, we must protect the 170 billion trees in imminent risk of destruction. They are crucial carbon storages and essential ecosystems to protect biodiversity," they state.16

Worldwide, communities have been coming together to encourage reforestation. In Kenya, 51 million trees have been planted since the late 1970s, largely at the hands of local, rural women.

Likewise, in Colombia, more than 54,000 trees have been planted in 32 communities since 2016, and each area has its own local tree nursery. Pakistan is also committed to the Billion Tree Tsunami, with plans to reforest more than 860,000 acres of deforested land.17

The Root Brain and the Intelligence of Trees

Amidst the growing realization that plant life may be key to undoing some of the harm man-made pollutants have done to the Earth is the acknowledgement that plants are not benign objects but rather living beings.

An extensive underground network connects plants by their roots, serving as a complex interplant communication system or "plant Internet," if you will. One organism is responsible for this amazing biochemical highway: a type of fungus called mycorrhizae.

Suzanne Simard, a professor in the Department of Forest & Conservation at the University of British Columbia, is among those who have revealed that this mycorrhizae network connects trees to each other in mind-blowing ways, such that trees might be viewed as beings with a capacity for intelligence, decision-making, learning and memory.

Speaking to Nautilus, Simard expanded on the root brain hypothesis first suggested by Charles and Francis Darwin:18

"Behind a growing root tip is a bunch of differentiating cells. Darwin thought those cells determined where roots would grow and forage. He thought the behavior of a plant was basically governed by what happened in those cells.

The work I and others have been doing — looking at kinship in plants, how they recognize each other and communicate — involves the roots. Except now we know more than Darwin did; we know that all plants, except for a small handful of families, are mycorrhizal: The behavior of their roots is governed by symbiosis.

It's not just those cells at a plant root's tip, but their interaction with fungus, that determines a root's behavior. Darwin was onto something. He just didn't have the full picture. And I've come to think that root systems and the mycorrhizal networks that link those systems are designed like neural networks, and behave like neural networks, and a neural network is the seeding of intelligence in our brains."

Among some of Simard's and colleagues' fascinating work is evidence that old trees recognize their own seedlings and change their behavior to provide them advantages. "A parent tree will even kill off its own offspring if they're not in a good place to grow," Simard explained.19 She points out that while such ideas may seem wild, ancient peoples also expressed them:20

"I f you go back to and listen to some of the early teachings of the Coast Salish and the indigenous people along the western coast of North America, they knew that [trees can be connected by fungal networks and communicate] already. It's in the writings and in the oral history.

The idea of the mother tree has long been there. The fungal networks, the below-ground networks that keep the whole forest healthy and alive, that's also there.

That these plants interact and communicate with each other, that's all there. They used to call the trees the tree people. The strawberries were the strawberry people. Western science shut that down for a while and now we're getting back to it."

Everyone Can Help Plant Trees

One of the simplest ways to get involved in supporting the environment and reconnecting to nature is by planting trees. Even if you live in a region where you can't plant trees, or in an apartment with no backyard, you can donate or gift trees to be planted.

Every tree makes a difference, and if you're feeling competitive, the Trillion Tree Campaign website has a tool for you to set a tree-planting goal and keep track of your target.21

The Campaign suggests everybody should plant at least 150 trees, with those in wealthy countries setting a higher target of 1,000. Mercola.com, in partnership with Trees for the Future, is also getting involved and has planted over 200,000 trees to date.22