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The health of those living in congested towns and cities is increasingly affected by pollution, which can cause breathing difficulties and other serious conditions. Once that polluted air enters a building, it’s essential that these pollutants be removed to ensure occupant safety and wellbeing. Steve Hope, from Guardian Water Treatment, discusses.


INDOOR AIR QUALITY BSEE


abelled as the ‘greatest environmental risk to health’ by the World Health Organisation, ambient air pollution is something that needs to be tackled on the global stage, yet another driver behind reducing our reliance on fossil fuels in our cars and power stations. The damage caused by poor air quality ranges from the deadly (it is estimated some 40,000 deaths a year are caused by it), to less serious ailments which, in a working environment, could lead to time off and loss of productivity – something that should ring alarm bells with business owners. In fact, a survey by the Building Engineering Services Association (BESA) in 2016 reported that almost 70% of office workers believe poor air quality in their place of work is having a negative effect on their day-to-day output.


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So, while the air outside is hard to control, once indoors ensuring it is clean and safe should be a priority, a task that must begin when a building is constructed by choosing appropriate Air Handling Units (AHUs) and ventilation. Once in situ, ongoing maintenance is essential to keep air moving plant working efficiently, without contamination.


Keeping ductwork and ventilation clean


For building occupants in our towns and cities, opening a window, the simplest form of ventilation, may not be a healthy option, making the role of AHUs even more important. And, with our increasing desire to create air tight, waste free properties, mechanical ventilation is increasing in demand to avoid stale environments, devoid of natural air intake.


It is essential that ventilation and ductwork systems have a general level of cleanliness as a minimum. AHU grilles, for example, should be free from dust and grime that could restrict airflow,


TACKLING POOR IAQ Keeping the outside out ‘


cause unwanted germs and even stop the unit working altogether. As a first step, filtration is key to prevent debris entering the system in the first place. Regular cleaning of coil sections should take place on a six to twelve monthly basis, with filters changed every three to six months, depending on the type of system and the area served. Filters used in kitchen ductwork, for example, may need more frequent attention. It’s worth noting that ductwork cleaning in kitchens is not only about air hygiene, it is also essential for mitigating fire risk as the high volumes of grease often expelled during cooking can be flammable. Many insurers now require specialist contractors to undertake the cleaning in accordance with B&ES TR/19 – Internal Cleanliness of Ventilation Systems, which details best practice guidance for keeping ventilation ductwork clean.


Other ‘high risk’ locations include healthcare premises, where ensuring air is clean is vital to the health and wellbeing of vulnerable patients. HTM 03 01: Specialised Ventilation for Healthcare Premises states annual inspections are a must, with the performance of critical ventilation systems (such as those serving operating theatres) verified in particular. As hospitals can be germ filled places, it’s important that plant doesn’t contain any material or substance that could support the growth of micro-organisms. A pro-active approach to ductwork and ventilation should be bespoke in its nature. While the guidelines and standards describe timeframes and necessary activities, it is crucial that how a building is used (and changes) is considered. For example, in an office environment, layout alterations to accommodate new staff or different ways of working may leave an existing AHU system struggling to meet its requirements. Regular appraisal of a building and IAQ monitoring will help to ensure that air quality remains at acceptable levels.


Air quality monitoring


Monitoring air quality will allow building managers to ensure staff safety and address problems quickly, before bigger issues arise. Covering important factors, such as temperature, pollutants, humidity levels, carbon monoxide, dust, fungus and bacteria, IAQ monitoring will not only highlight hygiene levels, it will also flag up issues that could cause operational problems.


For employers, IAQ monitoring contributes towards compliance with Control of Substances Hazardous to Health (COSHH) Regulations. Regulation 7 (1) requires the employer prevent exposure and where this is not practicable, ensure that any exposure is adequately controlled. Without monitoring, employers have no way of knowing what substances their staff come into contact with. The air we breathe is one of the fundamentals of human life and, as such, should be treated with due respect. Apart from health reasons, poor IAQ may reduce employee output and affect the efficient running of associated systems, so it is a cost issue as much as anything. The best approach should always be holistic, covering design, monitoring and fit-for-purpose maintenance.


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uFresh-air should flow at minimum of 8 litres per second, per person. uAreas with an air flow velocity in excess of 0.25 to 0.3 metres per second should be considered draughty.


IAQ essentials


uAn area with an air flow velocity of 0.1 metres per second is stagnant.


uFor an area of normal temperature, air velocities should be between 0.1 to 0.15 metres per second, and 0.25 metres during the summer.


uWhere a room houses machinery, separate extract ventilation should be included.


uAir inlets for the ventilation system should be sited to avoid introducing pollution from outside the building – a particular issue in city centres or areas of high traffic.


It is essential


that ventilation and ductwork systems have a general level of cleanliness as a minimum. AHU grilles, for example, should be free from dust and grime that could restrict airflow, cause unwanted germs and even stop the unit working altogether.





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