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Green Air: On Air

GreenAir:OnAir - Episode 1 - 3 things everyone should measure

Very few offices actually present a risky place to work, so a suitable air monitoring regime should assist in creating a comfortable, and more importantly for an employer, a productive place to work.

There are three things that everyone who has or works in a building of any sort, should worry about:
- Thermal comfort – temperature and relative humidity
- Fresh Air – level of fresh air within a space
- Hygienic Cleanliness – level of moulds, fungi and bacteria

Thermal comfort

Research shows that just a few degrees change in temperature can adversely affect productivity. Studies by Cornell University showed 71.5o F (21.9oC) to be optimal for 100% productivity, whereas only 90% productivity was achieved when the temperature rose to 87oF (30.5oC). There is also work being done with AIRLOG on a human thermal modelling system which will allow developers of new and existing accommodation to see how different individuals will respond to the designed environmental conditions.

Testing and monitoring temperatures on a regular basis can check that your environment falls within optimum parameters and/or those set within lease agreements. This often identifies overall issues associated with heating and ventilation systems but also with solar gain or over-occupation in certain areas of a building which can then be addressed. Conversely it also identifies where the environment is within parameters and issues are actually caused by individual factors such as inappropriate dress or specific seating positions – next to the window or below ventilation supply grilles.

Humidity levels can adversely affect individuals with specific conditions or requirements such as allergies for example or by users of contact lenses etc. As with temperature testing, it can identify issues with the heating and ventilation systems and so changes can be made to get closer to an optimum environment for increased productivity.

Fresh Air

Lack of fresh air in enclosed environments causes lethargy and due to poor ventilation can contribute to an accumulation of contaminants; indoor air can be 2 to 10 times more dangerous than the outside environment for this reason.

Carbon dioxide levels are used as a surrogate indicator to establish whether there is sufficient fresh air being supplied for the number of staff in the workspace. The HSE limit for CO² is much higher than would ever occur within a workplace but the level at which CO² will start to affect productivity is much lower – 800-1000ppm. Various research, such as that from Berkeley Lab, has shown a detrimental effect on judgement at increased CO² levels and we have all experienced that wave of lethargy come over us when an office or meeting is stuffy; not exactly conducive to productivity.

The greatest source of CO² in an office is from people. A ventilation system working correctly should be providing sufficient fresh air and removing pollutants generated from staff and the building itself. However, many occupiers do not have control over this system. We would recommend that occupiers insist on acceptable maximum CO² levels being written into lease agreements and that they undertake independent testing.

Carbon monoxide levels should be measured when there is a specific risk for instance through direct fired gas heating systems, depots and car-parks. In a more general workplace it is used as a surrogate measure of the effectiveness of the extract system and to assess the ingress of external pollutants to the workplace via air handling systems.

Hygienic cleanliness

This covers moulds, fungi and bacteria, of which there is a vast array and so impacts on comfort and wellbeing. Impacts could be itchy eyes, runny noses, allergic reactions, nausea and headaches.

Complaints from individuals in an office are usually about illness like coughs and colds. These viruses and bacterial infections are passed amongst staff and visitors usually by contact or through airborne ‘human effluvia’ and brought in by one or more individuals.

With regards to bacteria and fungi etc, the usual first remark is associated with legionella. The legionella bacterium is a water borne organism living only in water and water droplets that proliferate within a certain temperature range. Many bacteria and fungi are ubiquitous in the indoor air environment and their presence should not cause alarm. However, consistently high counts should be investigated and possible causes identified. Where there is a cause for concern additional samples should be collected and evaluated to identify the organisms and so, the source.

Snapshots v Day long surveys

Any indoor environment changes throughout the day, due to constant changes in occupancy, external weather and heating and air conditioning systems controls configuration and strategy with the added complications of emissions from building materials and furnishings. A ‘snapshot’ of the environment with measurements collected early in the morning can produce very different results to measurements collected from the same place late in the afternoon. A survey that covers the full working day is a desirable approach to gain a better understanding of the environment throughout the working day.

For most building occupiers, Green Air Monitoring would recommend a ‘Basic 5’ workday survey, however we would be pleased to discuss particular issues you may feel significant and then we can design a monitoring regime that is relevant over the short, medium or long-term.

01 May 2014