Globally, people populating urban areas spend as much as 90% of their time indoors (Weyens et al., 2015). While walls and a roof may provide sufficient protection from the elements, even the rogue intruder, the rooms we barricade ourselves in more often than not do us more harm than good. Building designs intended to be more energy efficient are frequently ventilated poorly, contributing to acute levels of indoor air pollution which the EPA has identified as a top five risk to public health. Concentrations of particulate matter within buildings oftentimes exceed ten times the level found outdoors, only outdone by findings that suggest amounts of carcinogenic compounds measured indoors can be greater than 70 times the level of its outdoor counterpart (Weyens et al., 2015). With the documented link between large quantities of indoor particulate matter and negative health effects, including higher rates of mortality and respiratory disorders, finding efficient ways to ensure clean air within the home or workplace is imperative.
As outlined in our previous blogpost on the efficacy of HVACs, these systems which are ubiquitous in modern buildings routinely exacerbate indoor air pollution through improper installation and/or negligence. However, some of the latest trends in environmental biotechnology, a field rapidly growing in response to shifts in climate, has demonstrated the potential for plants to be used in concert with properly functioning HVACs to remedy contaminated indoor air through a process called phytoremediation. As it turns out, the aboveground parts of plants, specifically their leafs and stems, are incredibly effective at drawing significant amounts of pollutants out of the air. Through leaf fall and other processes, these pollutants are subsequently absorbed, metabolized, sequestered and excreted by the soil and rhizosphere below.
Another component making plants an incredibly useful tool for air purification are the thousands, if not millions of microbes accompanying them. Fungi and bacteria are well known to have a symbiotic relationship with their plant host, helping them mitigate stress and increase nutrient uptake among other things. These microorganisms, in fact, also perform a pivotal role during phytoremediation by squestrating pollutants, in turn promoting further plant growth.
Of nearly 120 plant species assessed for their ability to remove pollutants from indoor air, the common spider plant (Chlorophytum comosum) is one of the most active (Gawrońska & Bakera, 2015). As its name suggests, the plant’s array of long, reaching leafs provide ample surface area for harmful particulate matter to accumulate. Paired with a vigorous rhizosphere, the plant has demonstrated the ability to remove toxic nitrogen dioxide, carbon oxide, ozone, benzene, toluene, ammonia, cigarette smoke, and formaldehyde, the last of which it can utilize as a source of energy directed towards biosynthesis of new molecules (Gawrońska & Bakera, 2015).
While it is true that phytoremediation takes longer to rid indoor air of its pollutants, it is much cheaper, environmentally friendlier, and more dynamic in its application than standard technical methods of indoor air filtration. Considering the fact that trees and shrubs in US urban areas absorb nearly 215,000 tons of particulate matter a year (which equates to 969 million dollars), introducing the limitless abilities of plants to purify through bioremediation into the indoor sector is the logical and necessary next step (Weyens et al., 2015).
Gawrońska, H., and B. Bakera. “Phytoremediation of Particulate Matter from Indoor Air by Chlorophytum Comosum L. Plants.” Air Quality, Atmosphere, & Health 8.3 (2015): 265–272. PMC. Web. 7 July 2017.
Weyens, Nele et al. “The Role of Plant–Microbe Interactions and Their Exploitation for Phytoremediation of Air Pollutants.” Ed. Jan Schirawski. International Journal of Molecular Sciences 16.10 (2015): 25576–25604. PMC. Web. 7 July 2017.