**1. Introduction**

Air pollution is one of the major threat to ecosystem services and imposes negative impacts on all living organisms [1]. The composition and type of air pollutants in a particular region majorly depends upon its sources, emission rate, and climate conditions. The pollutants that contribute to air pollution are as follows: carbon monoxide (CO), lead (Pb), nitrogen oxides (NOx), ground-level ozone (O3), sulfur oxides (SOx), particulate matter (PM), volatile organic compounds (VOCs), poly-aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) [2–4]. Ground-level ozone is a colorless secondary pollutant and is produced when NOx and VOCs react in sunlight and stagnant air [5]. On the other hand, particulate matter (PM) is comprised of carbonaceous particles with accompanying adsorbed organic substances and reactive metals [6]. Gaseous pollutants such as SOx and NOx also aid particle formation through complex atmospheric photochemical reactions involving ammonia released from agricultural fields [5]. Road traffic is a significant source of NO2, particularly from diesel automobiles that contribute to the global air pollutants emission in large cities. However, the main sources of SO2 are industrial emissions and maritime transportation.

Global organizations are concerned about the increasingly deteriorating air quality because it is believed to be one of the leading causes of approximately 3.1 million fatalities each year [7–10]. The average life expectancy of urban populations is decreasing as exposure to high levels of air pollutants over a longer period of time. Pollutants like fine particulate matter (PM2.5) and ground-level ozone are unquestionably linked to an increase in mortality rate [11]. Particulate matter alone causes23% of total damage to human health despite representing only 6% of the total air pollutants [12]. Pollution-related illness has been estimated to cause as many as 9 million premature deaths during 2015, which was three times greater than the number of deaths from other illnesses such as malaria, AIDS, and tuberculosis altogether [13]. Alongside, the air quality of the indoor environment has become a global issue as people in urban areas spend more than 90 percent of their day in office spaces or residential areas [14]. Poor indoor microclimate adversely affects the health, happiness, and productivity of occupants [15]. Major indoor air pollutants such as PMs, VOCs, PAHs, PCBs, NH3, SO2, H2O2, HNO3, HNCO, CO, and H2S upon inhalation are linked to a range of health problems including asthma, heart disease, reproductive problems, neurological issues, irritate the eyes, and respiratory disorder [13].

Remediation of these pollutants for sustaining ecosystem and human health using either physical, chemical, or biological approaches is applicable but limited due to the cost, labor requirements, and safety hazards [16]. Here, phytoremediation can be effectively used as an alternative technique, and it is gaining popularity, acceptance, and implementation due to ease and an array of benefits. Phytoremediation is the use of plants and associated microorganisms to reduce or degrade the concentrations or toxicity of pollutants. Phyto-stabilization, rhizo-degradation, phyto-extraction, phyto-degradation, phyto-volatilization, and phyto-filtration are the fundamental mechanisms of the phytoremediation process. The efficiency of these processes can be improved by using synthetic and natural additives, suitable microbes and host, and genetic engineering/editing. Various modes of biological remediation include microbes-related remediation, enzyme-assisted remediation, vermi-remediation, phyto-remediation, and zoo-remediation exists in nature. However, microbialassisted phytoremediation including plants and microbes is one the most effective, sustainable, and economical approach to reduce harmful pollutants from the environment [17, 18]. The bioremediation of air pollutants by the phyllosphere or microbes associated with the leaves, not just the microbes themselves, is known as phyllo-remediation. While rhizo-remediation is the process of degrading organic contaminants in the soil region around plant roots (the rhizosphere), typically as a consequence of enhanced catalytic activities of root associated microbes [19–21].

Various ornamental plant species have been used for the enhancement of air quality. Previously, *Chamaedorea elegans* and *Opuntia microdasys* plants have been shown to reduce the concentrations of formaldehyde and BTEX. Also, *Chlorophytum comosum* L. plants are able to accumulate indoor particulate matter pollutant (PM10, PM2.5, and PM0.2). The rhizospheric microbes associated with the *Aloe vera, Tradescantia* 
