The role of air purifier in reducing indoor airborne particulate matter to improve respiratory health

Abstract

Introduction: The recent surge in respiratory diseases has heightened concerns about air quality, particularly for individuals who spend most of their time indoors. Air purifiers, alongside good ventilation and self-protection are now among the preferred methods for ensuring clean and breathable air. Discussion: Reducing the levels of airborne pollutants is crucial for maintaining respiratory health, reducing the incidence of respiratory diseases, and preserving pulmonary function. Particulate matter (PM) serves as a key indicator of air quality. Conclusion: Air purifiers, such as those with High-Efficiency Particulate Air (HEPA) filters, are closely linked to improved air quality by effectively reducing particulate matter (PM), thereby offering long-term health benefits.

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Kristy & Putra
216 Jurnal Prima Medika Sains Vol.6 No.2
J Prima Med Sains (2024) 6(2):216-219
doi.org/10.34012/jpms.v6i2.6144
REVIEW
*
The role of air purifier in reducing indoor airborne particulate
matter to improve respiratory health
Anastasia Kristy*, Wayan Wahyu Semara Putra
Abstract
Introduction: The recent surge in respiratory diseases has heightened concerns about air quality, particularly for
individuals who spend most of their time indoors. Air purifiers, alongside good ventilation and self-protection are now
among the preferred methods for ensuring clean and breathable air. Discussion: Reducing the levels of airborne
pollutants is crucial for maintaining respiratory health, reducing the incidence of respiratory diseases, and preserving
pulmonary function. Particulate matter (PM) serves as a key indicator of air quality. Conclusion: Air purifiers, such as
those with High-Efficiency Particulate Air (HEPA) filters, are closely linked to improved air quality by effectively
reducing particulate matter (PM), thereby offering long-term health benefits.
Keywords: air purifier, respiratory disease, particulate matter, HEPA
Introduction
The rise in respiratory tract infections due to air pollution and the COVID-19 pandemic, which
required extended periods of indoor living and self-isolation, has significantly raised awareness about the
importance of indoor air quality.1 Poor air circulation and air quality can have a profound impact on human
health leading to various health risks, such as cardiovascular events, and respiratory problems.1 Therefore,
developments regarding these issues are being studied to improve air quality.
Air purifiers, which are devices designed to filter airborne particulates and improve respiratory air
quality, have gained widespread attention.2 Nowadays, a variety of air purifiers are available, incorporating
different technologies.3 It is categorized into several types, such as high-efficiency particulate air (HEPA)
filters, ionization air purifiers, and electrostatic precipitator (ESP) purifiers. Each type of air purifier has its
own advantages and limitations. For instance, while ESP purifiers are cost-effective and easy to use, they
are less efficient at filtering particulate matter compared to HEPA purifiers. Ionization air purifiers are
popular due to their low noise output, whereas HEPA purifiers are considered the most effective for
improving air quality. Selecting the right air purifier is crucial to achieve optimal indoor air quality.
Air particulates and their impact on health
Air quality is determined by the content of airborne pollutant particulates. According to the U.S.
Environmental Protection Agency (EPA), pollutants in the air are classified into six main categories: ozone
(O3), particulate matter (PM 2.5µ, 2.5-10µ, and PM 10µ), nitrogen dioxide (NO2), sulphur dioxide (SO2),
carbon monoxide (CO), and lead (Pb).4 Larger particulates, sized 10µ, generally cannot penetrate the
respiratory tract. However, particulates sized 2.5-10µ can penetrate the upper respiratory tract, and
particulates smaller than 2.5µ can reach deeper into the lower respiratory system, including the alveolar
sacs, in which they may cause significant health issues. As a result, the PM2.5 concentration is used as an
indicator for assessing air quality.
Affiliation
Department of Pulmonology and Respiratory Medicine, Wangaya General Hospital, Denpasar, Indonesia
Correspondence
anastasia_kristy@hotmail.com

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To monitor air pollution levels, air quality index (AQI) is used in several countries, including
Indonesia.4,5 The AQI assigns a numerical value to the level of air pollution, where a higher value indicates
worse air quality and greater potential health risks. This index helps the public understand the level of
pollution and its impact on health.5
Pollutants and particulates can be found both outdoors and indoors. While the types of particulates
and pollutants circulating indoors and outdoors are similar, there are significant differences between the
two based on their concentrations. These differences mainly occur because outdoor pollutants come from
sources such as forest fires, trash burning, and transportation emissions. Indoor pollutants, however, are
primarily generated by activities like cooking, heating combustion, poor ventilation, tobacco smoking, and
certain building materials.5 With proper ventilation in the room, reducing tobacco smoking, choosing the
right furniture materials, and controlling sources like cooking and heating combustion might help improve
indoor air quality.
Particulate sources in developed and developing countries are typically different. In developed
countries, the primary source of particulates is environmental tobacco smoke (ETS). A study of 73 homes
in Italy found higher levels of PM2.5 in homes with active smokers compared to those without. In
developing countries, particulate sources include biomass, as well as the use of charcoal and coal for
cooking or heating. The combustion of these materials results in the release of carbon monoxide, nitrous
oxide, particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs).5,6 The inhalation of these
chemicals is believed to have a detrimental effect on human health, affecting mucociliary clearance,
increasing the adherence of microorganisms to respiratory cells, impairing the immune system, and causing
a decrease in lung function. This can also elevate the risk of infections, respiratory symptoms, and
exacerbations of chronic obstructive pulmonary disease (COPD) and asthma, potentially leading to more
hospitalizations.5 PM2.5 can remain airborne and adhere to surfaces for hours after exposure, further
impacting indoor air quality.6,7 Additionally, the growing popularity of electronic cigarettes has contributed
to increased PM2.5 concentrations indoors, reaching 197–818 μg/m3.8
A 2015 study in the U.S. found that long-term exposure to PM2.5 could cause changes in lung
function, such as forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the
FEV1/FVC ratio. The study indicated that an increase of 2 µg/m3 in PM2.5 was associated with a 13.5 ml
lower FEV1 and an additional decline of 2.5 ml per year.6 The main factor contributing to lung disease from
PM2.5 exposure is increased oxidative stress. Oxidative stress is pathological damage resulting from
excessive reactive oxygen species (ROS) production or an imbalance between antioxidant systems in tissues
or cells.9 ROS accumulation in mitochondria leads to increased membrane permeability, morphological and
functional changes, and mitochondrial cell death and damage. Nuclear factor erythroid-2 related factor
2/antioxidant responsive element (NRF2-ARE) is a cytoprotective component crucial for maintaining
cellular balance.10 The antioxidant heme oxygenase 1 (HO-1) is regulated by the NRF2-ARE pathway and
catalyses heme to produce carbon monoxide (CO) and biliverdin. HO-1 also plays a role in BEAS-2B cell
damage.9 BEAS-2B cells, derived from the bronchial epithelium, are involved in lung carcinogenesis and
infections.11
Apart from oxidative stress mechanisms, exposure to indoor pollutants can increase neutrophil
inflammation, damage macrophage phagocytosis, reduce bacterial and mucociliary clearance, and disrupt
the alveolar and capillary barrier in the lungs, resulting in a decreased immune response to bacterial and
viral infections.12 Beyond respiratory infections, exposure to pollutants and particulates can induce genetic
and epigenetic changes that persist after exposure ends. These changes may contribute to impaired lung
development in children, airway hyperactivity, asthma, and chronic obstructive pulmonary disease (COPD)
in adulthood.12,13
Air purifiers: types and effectiveness
Several strategies exist to reduce air pollution, such as switching to cleaner cooking fuels like
liquefied petroleum gas (LPG) and reducing tobacco smoke. While these strategies focus on reducing
pollutant sources, technological advancements have also introduced new methods for directly improving
air quality. Recently, air cleaning interventions using machines, commonly known as air purifiers, have

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218 Jurnal Prima Medika Sains Vol.6 No.2
gained attention.12 Nowadays, there is a wide variety of air purifiers available, differing in models and
technologies used. In general, air purifiers can be divided into two types: those which work by filtering and
absorbing harmful particulates and gases or by catalysing oxidation reactions to neutralize pollutants.14
Aside from that, air purifiers also reported to be effective in reducing pollutant and particulate
concentrations indoors by diluting ventilation.2,12,14 Based on the technology used, air purifiers can be
categorized as filter-based, water-based, ionization, ozone, photocatalytic, and hybrid types.14
The most widely used air purifiers fall into categories based on the technology they use. These
include those with mechanical filtration, such as high-efficiency particulate air (HEPA) filters, ionization air
purifiers, and electrostatic precipitator (ESP) purifiers.15 HEPA air purifiers are widely regarded as the most
effective for removing particulate matter, with the ability to capture 99.97% of particles with a diameter of
0.3 µm. However, they require regular replacement and are difficult to clean, making them more expensive
in the long run. 16
ESP air purifiers, while less effective at filtering particulates, are easier to clean and do not require
frequent replacements, making them more cost-effective. Ionization purifiers, known for their low noise
production, are popular for use in schools and other spaces where noise is a concern.15 One study
concluded that ion-type air purifiers could reduce PM2.5 concentrations by 50% (from 8 µg/m3 to 4 µg/m3)
without significant changes in lung function in older adults. Another study involving 44 boys and girls aged
11–14 found improved lung function, reduced airway inflammation, oxidative stress, and a decreased risk
of ischemia after using ion-type air purifiers. Measured parameters included FEV1, FVC, ambulatory
electrocardiography, and FeNO levels.15
Despite their benefits, air purifiers have limitations. They are unable to eliminate all pollutants, and
they may lead to higher energy consumption and noise levels, particularly when used continuously.5 These
factors must be considered when evaluating the effectiveness and suitability of air purifiers for improving
indoor air quality. The effectiveness of air purifiers is also influenced by environmental factors, such as the
ratio of the device to the room size, device placement, and ventilation.5 Thus, while air purifiers can
significantly improve indoor air quality, they should be considered as part of a broader strategy for
managing air pollution.
Discussion
Numerous studies have shown that the use of HEPA air purifiers leads to improvements in air quality
that is eventually beneficial to cardiovascular and respiratory function. Specifically, HEPA filters have been
linked to improved peripheral artery tone, reduced systemic inflammation and enhanced endothelial
function, all of which are associated with lower cardiovascular risks. Moreover, the use of HEPA filters has
been shown to benefit individuals with asthma, particularly those living with pets, by reducing symptoms,
airway hypersensitivity, nighttime symptoms, and medication use.17 Additionally, air purifiers can alter
airborne bacterial colonization compared to control conditions, which may reduce respiratory infections
due to fewer bacteria and decreased transmission risk.18
Therefore, air purifiers using HEPA technology are reported to provide positive outcomes for
respiratory and cardiovascular health. Though this is a promising study, they should not be seen as a
standalone solution for improving indoor air quality. Other conventional interventions, such as improving
ventilation, reducing tobacco smoke exposure, switching to cleaner cooking and heating methods, and
using eco-friendly building materials, can lead to even more substantial improvements in indoor air quality.
Combining these approaches with natural methods like plant-based air purifiers may result in more
effective, long-term solutions for enhancing indoor air quality. Further research is needed to explore the
long-term effects of air purifiers and integrated technologies to ensure optimal air quality outcomes.
Conclusion
In conclusion, the rise in respiratory diseases linked to poor air quality has highlighted the need for
effective solutions, particularly in indoor environments. The COVID-19 pandemic has further emphasized
the importance of indoor air quality, and the role air purifiers can play in mitigating health risks. While air
purifiers with HEPA technology are shown to be effective, there are opportunities for further research,

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Jurnal Prima Medika Sains Vol.6 No.2 219
particularly concerning their long-term health effects and the limitations of existing models. In addition to
air purifiers, strategies such as improved ventilation, reduced tobacco smoke exposure, and optimized
heating and cooking methods are essential for creating healthier indoor environments. Public awareness
campaigns and policies that support cleaner air should also be promoted. These efforts are key to improving
public health and ensuring the continued effectiveness of air quality management.
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