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The rising tide for clean air: Bridging the gap between aspiration and action

There appears to be a chasm between our avowed goal of breathing and providing clean air and existing filter designs. Can they provide the required performance smartness we demand in achieving filtration perfection? Dr Iyad Al-Attar asks.

| | Dec 4, 2013 | 3:29 am
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nov2013-spotlight01Day by day, the clamour for not only breathing clean air but also for supplying it to several industrial applications that highly influence our life and its style is growing louder. Our well-pronounced reliance on it is substantially increasing. But what are we doing about it?

Demand for clean air

We all demand the best air quality in any indoor environment we spend time in. The industry, too, is increasingly insisting on the need for clean air in critical industrial applications. This certainly highlights the importance of filtration in providing clean air and emphasises the need for a greater understanding of the actual performance of air filters installed in Air Handling Units (AHUs) and in the intake of gas turbines.

Filters in action

When we buy a smart phone, we assess its intelligence according to its capabilities and its data processing power; manufacturers even interact with potential users to predict what they want and direct them towards the appropriate application. However, an integrated factor of a smart phone has to also deal with the owner’s intelligence in capitalising on its features. Air filters, too, can get smarter. However, a major part of its efficient use relies on the owner’s willingness and understanding in order to optimise its performance.

Another aspect of filter success in action is its accurate performance prediction, which is critically important to estimate filter lifetime, reduce energy and maintenance operating costs. However, when air filter performance deviates from that predicted by laboratory results, operational concerns emerge regarding air filter selection. Further, no one can afford to overlook the importance of atmospheric dust characterisation (See Figure 1) in recognising the challenge of dust loading of filters. In addition, other factors, such as effects of face velocity, filter design, filter media properties and the associated Most Penetrating Particle Size (MPPS) are equally important. Another parameter that can contribute to the filter performance deviation is the high dust concentrations due to sandstorms in our region, which may not match the concentration specified by the international standards.

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Compromising filter efficiency to lower pressure drop

What drives filtration engineers? Is it the same drive as that of building owners and operators? Is it merely lowering operational and maintenance costs? Should that be done at the expense of lowering the quality of the filtration material, or reducing design features, or minimising parameters, such as filter depth and filter class, or even using a different design? Are there untouched parameters that one should not alter or, at least, leave until they are the last resort?

It seems to be a trend that when a high-pressure drop is experienced, the decision immediately tends to lean towards lowering filter efficiency. At this point, we pause and ask: What is our objective? Is it to save energy? Usually the question is, how can we save energy while improving or, at least, maintaining the filter efficiency? However, on the contrary, the tendency should be directed towards optimising the efficiency while lowering the pressure drop. Therefore, prior to lowering the filter efficiency, we must consider the consequences on the human occupants and the HVAC and/or gas turbine applications we are trying to protect. Further, a cost analysis must be conducted to consider the additional maintenance cost that would be required as a consequence of lowering the efficiency. Same consideration has to be looked at when we analyse the impact of lowering IAQ on productivity and absenteeism.

Living in the 21st century, I can only imagine that the ongoing research and development is moving towards providing the world with efficient and aerodynamic air filters. Settling for the option of lowering filter efficiency to save energy would imply that we are surrendering ourselves to old techniques that provide higher dust concentration settlement on the equipment and human occupants. In my judgment, lowering the efficiency to lower the pressure drop of the filter to save energy is simply an easy way out, and the road map to an expensive filtration mistake.

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The surprise factor

I accept the fact that the Icelandic volcano that spewed ash three years ago took us by surprise and questioned our readiness as to whether or not we humans could combat such environmental cataclysms. However, what strikes me as strange and unacceptable is that we have been encountering sandstorms for centuries, and yet, every time we get one, we seem to be both stunted by and unready for it. We still seem to be in the questioning stage: What can we do to tackle them? How can air filters sustain such high dust concentration? And yes, what is wrong with 100% air recirculation as a quick “over-the- counter” solution to protect Air Handling Units of the indoor spaces?

A firm stand on the sand

I believe what we need is a firm stand on the sand to investigate and correlate adverse health impacts, such as respiratory and heart disorders towards sandstorms. In fact, several studies suggested that sandstorms could be related to the increased risk of respiratory diseases, daily mortality and primary haemorrhagic stroke admission1,2,3. Other studies have shown PM2.5 and PM10 of sandstorms have cytotoxic effects on the human lungs and a possible consequential effect on a completed DNA synthesis4. Another study has shown that the ambient particles collected during Asian Dust Storm (ADS) events could increase lung inflammation and injury5. While previous studies have addressed ADS, little has been accomplished in terms of quantifying sandstorms and correlating them to health effects in the GCC region.

Smart filtration

Certainly, if we hold the smartest phones in our hands, which, by the way, requires cleanrooms to manufacture its parts, why don’t we demand the smartest air filters for our indoor spaces? Why do we surrender ourselves to conventional techniques to combat such storms? Why don’t we grant such storms the research they deserve? Why don’t we characterise sandstorms particle by particle? If sandstorms have been visiting us for centuries, why don’t we take a stand and pay the storm a visit?

Dr Iyad Al-Attar is an Air Filtration Consultant. He can be contacted at: iyad@iyadalattar.com

References:

  • [1]Chen, Y.S., Sheen, P.C., Chen, E.R., Liu, Y.K., Wo, T.N., Yang, C.Y., 2004. Effects of Asian dust storm events on daily mortality in Taipei, Taiwan. Environmental Research 95, 151-155.
  • [2] Kwon, H.J., Cho, S.H., Chun, Y., Lagarde, F., Pershagen, G., 2002. Effects of the Asian dust events on daily mortality in Seoul, Korea. Environmental Research 90, 1-5.
  • [3] Yang, C.Y., Chen, Y.S., Chiu, H.F., Goggins, W.B., 2005. Effects of dust storm events on daily stroke admissions in Taipei, Taiwan. Environmental Research 99, 79-84.
  • [4] Deng, F., Guo, X., Liu, H, Fang, X.,Yang, M. Chen, W. “Effects of dust storm PM2.5 on cell proliferation and cell cycle in human lung fibroblasts” Department of Occupational and Environmental Health Sciences. 632-638.
  • [5] Lei, Y.C., Chan, C.C., Wang, P.Y., Lee, C.T., Cheng, T.J., 2004. Effects of Asian dust event particles on inflammation markers in peripheral blood and bronchoalveolar lavage in pulmonary hypertensive rats. Environmental Research 95, 71-77.

NOTE: Unless otherwise referenced, the images used in this article are copyright of the author.


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