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Study finds indoor HEPA filters significantly reduce pollution indoors.

Outdoor air pollution is a major contribution to air pollution. This study found high-efficiency particulate air filters (HEPA) used in the home significantly reduces fine particulate matter in the air compared to non-HEPA air filters. In this study, researchers monitored air quality for 12 weeks in homes enrolled patients who have respiratory issues. HEPA filters were found to reduce fine particulate matter by 55% and outside pollution coming inside reduced by 23%. Fine particulate matter is defined as small airborne particles often found in areas with heavy air pollution. When inhaled they can lead to respiratory difficulty, heart attacks, or exacerbate symptoms of COPD or asthma. The study was partially done in response to patients who had asked their doctor what they could do to protect their lungs during poor air quality days (Carlton, 2018).


In the US, there are over 5.6 million commercial buildings containing over 87 billion square feet of floor space. This translates as many people who spend a considerable amount of time in buildings with heating, cooling and ventilation systems at work and as consumers. Indoor air quality is more important than ever. After the oil embargo of the 1970’s the amount of outside air used in buildings was reduced. This lack of fresh outside air leads to the accumulation of indoor air contaminants.

Two main reasons for poor indoor air are the presence of indoor air pollution and poorly designed, maintained, or operated ventilation systems. Even the CDC has put forth building ventilation is one important factor affecting the relationship between airborne transmission of respiratory infections and the health and productivity of workers. In an effort to find ways to improve indoor air, ultraviolet germicidal irradiation (UVGI) for sterilization has been studied. It has been pioneered in hospitals and is now expanding into residential, office buildings, and vehicles.

And while the oil embargo did improve ventilation, it did little to address the pollution issue. Because of the significant amount of time spent indoors, the fact modern buildings mostly contain non-operable windows and lead to continued poor quality indoor air. Technology has finally found a way to install a combination of UVGI lamps and high-efficiency filtration. And while many studies have indicated major improvements, building owners are going to have to be willing to make the initial investment (deRobles, 2017).

Air pollution is a serious global public health problem that is managed most effectively by collective action to control emissions. Unfortunately, the concentration of ambient air pollutants currently exceed levels believed to substantially increase the risk of acute and chronic adverse human health effects. Affected areas include many of the urban communities where a majority of the world’s population now lives and works. Scientific studies have shown strong evidence for a growing number of adverse health effects of exposure to air pollutants. Personal exposure to ambient air pollutants occurs in both indoor and outdoor environments and levels of exposure depend on the fractions of time the individuals spend in various indoor and outdoor environments.

In the developed world, people spend about 90% of their day indoors with about 70% of that time in residential homes. And while ambient pollutants such as particulate matter (PM) infiltrate indoors from outdoors, concentrations are generally reduced compared to outdoors. Infiltration rates vary due to differences in building structures, air handling systems and building operating conditions. Generally, individuals with chronic cardiovascular (heart) or respiratory (breathing, lungs) disease, children, unborn and elderly are thought to be the most sensitive to major air pollutants. Improved management of chronic diseases that are affected by air pollution will help decrease the overall risk of adverse outcomes. In addition, reducing outdoor activity on high pollution days are also important (Lambach et al, 2015).

Exposure to air pollution remains one of the most global health risks today; in 2015 exposure to air pollution was the sixth leading risk factor for deaths in the US. It accounts for an estimated 88,400 deaths (3% of all deaths) and 1.49 million disability-adjusted life years. Many policy targets in the US over the past 50 years have focused on this issue. Unlike many cities in the US, New York City (NYC) is most affected by traffic-related air pollution, residential, commercial and institutional heating systems. And they are estimated to release 50% more fine PM than vehicles.

As of 2009, residential buildings burning #6 oil (5,500 boilers) and #4 oil (3,500 boilers) comprise 1% of all the city’s buildings but accounted for 86% of NYC heating-related PM. This study evaluated both indoor and outdoor air pollution in 48 northern Manhattan apartments in two successive winters; before and after building conversion to cleaner heating fuels in compliance with NYC Clean Heat policies.

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A primary analysis shows that outdoor PM fell significantly among apartments converting to cleaner fuels, largely driven by the reduction of upper floor apartments. Upper floor apartments largely observed a greater reduction in outdoor air pollution as compared to lower floor apartments. The Clean Heat policies are an important aspect of the effort to improve public health. Unfortunately, this study did not consider the realities of neighborhood inequalities and observed limited effect on indoor/outdoor air quality of upper Manhattan apartments. The study looked at 48 northern Manhattan apartments were followed during the two week heating period two years in a row. After integrating weather data and individual behavior patterns there it was noted there may be a relationship between the change in fuel and indoor/outdoor exposure (Gould et al, 2018).

Fine particulate matter has a diameter less than 2.5 microns. There have been many studies done that show indoor air quality is directly significantly influencing on health and is becoming increasingly worse. Some researchers have said that PM₂․₅ has existed since before man came in the form of volcanic eruptions and forest fires. When man came, they built houses effectively trapping the PM₂․₅ inside.

At present, cooking with biofuels is still the main source of indoor pollution. Reasonable measures should be used to control indoor PM₂․₅ concentration. High indoor PM₂․₅ concentration has a direct impact on human health. There are a plethora of relative problems that need further study. Things like high-rise buildings and super high-rise buildings are increasing which has better airtightness. Meantime because the outside air remains polluted, people are reluctant to open a window, trapping stale inside air.

Unfortunately, the public isn’t aware of this trend as a whole. Research scope of indoor PM₂․₅ needs to be broadened. At present most current researches focus on cities and towns with very little focus on rural areas. At the same time, it was reported in the WHO Indoor Air Quality Guidelines 2014 that there are over three billion in the poorest populations that use solid fuels for cooking and heating in stoves with low efficiency and high pollution. Indoor PM₂․₅ study needs to be deepened. So far adverse health effects have been determined, but the specific mechanism contribution of particles in different sizes and the effects of other pollutants still remain largely undetermined (Li et al, 2017).

Works Cited
Carlton, J.M. (2018). Indoor HEPA filters significantly reduce pollution indoors when outside air is unhealthy, study finds. Intermountain Healthcare News Release. https://intermountainhealthcare.org/news/2018/09/

deRobles, D. & Kramer, S.W. (2017). Improving indoor air quality through use of ultraviolet technology in commercial buildings. Creative Construction Conference Procedia Engineering. Science Direct. Doi:10.16/j.proeng.2017.08.021

Gould, C.F. et al. (2018). Soot and the city: Evaluating the impacts of Clean Heat policies on indoor/outdoor air quality in NYC apartments. PLoS ONE,13(6). https://doi.org/10.1371/journal.pone.0199783

Lambach, R., Meng, Q.,& Kipen, H. (2015).What can individuals do to reduce personal health risks from air pollution? Journal of Thoracic Disease,7(1). http://dx.doi.org/10.3978/j.issn.2072-1439

Li,Z., Wen, Q., & Zhang,R. (2017). Sources, health, effects and control strategies of indoor fine particulate matter (PM₂․₅ μ-microns): A review. Science of the Total Environment. Science Direct. http://dx.doi.org/10.1016/j.sciotenv.2017.02.029