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Be More Negative

15 December 2006

Six years of research has demonstrated that indoor environments, particularly in city centres and air-conditioned workplaces, need enhanced levels of negative ions if the occupants are to remain healthy and perform effectively, as this resume of the findings shows

ASUBSTANTIAL BODY OF RESEARCH DATA has been published over the past 70 years relating to the health and performance effects of two components of indoor air often overlooked in workplace studies - air-ions and airborne particulates. A broad range of physiological responses are attributed to these factors such as respiratory function, stress conditions, hormonal balance, immune response, skin conditions, wound healing, concentration and mood. There is also mounting evidence that negative ions have a biocidal capability. But is there sufficient evidence for professionals concerned with the productivity of workforces to look beyond the temperature, humidity and refresh rate of indoor air?

John Jukes, Andrew Jenkins and Julian Law's work has monitored the effect of combined negative ionisation and air filtration units on the health and productivity of 1,159 office, control room and call-centre staff working in eight different locations. Substantial reductions in sickness symptoms, sickness absenteeism and staff turnover were recorded with significant improvements in productivity.

British Telecom's policy of continuous improvement in workplace health and productivity provided them with an opportunity to conduct a series of studies over a six-year period. Air quality has long been a common source of complaint by staff, with dissatisfaction ratings of 70-80 per cent being normal. Previous studies by this team in the early 1990's had confirmed Dr Leslie Hawkins's findings that the ion and particulate content of the air had a major effect on staff health and performance. Air processors - combined ioniser and air filtration units - and ion measuring instruments were provided by Air Ion Technologies, who had also supplied Dr Hawkins for the majority of his trials.

The studies used the WESTRA symptom scoring system developed by John Jukes and Prof Derek Clements-Croome from the principles used in a number of major studies of Sick Building Syndrome (including Wilson & Hedge (1987) and G J Raw of the UK Building Research Establishment). The system comprises a list of 19 symptoms and the question is confined to whether any of those symptoms have been experienced in the previous four weeks. All of the trials used the same air processors. These units pass the air through a series of charged, pleated and activated carbon filters and then add negative ions to the recycled air.

Ions are a natural component of outdoor air, being molecules of the respirable gases which have either lost or gained electrons due to the ionising action of cosmic rays, solar radiation, UV, lightning, etc. These natural processes endow each millilitre of clean country air with approximately 1500 negatively charged and 1800 positively charged ions. The proportion of negative ions increases with altitude, under the influence of the earth's electric field, with alpine air containing as many as 10,000 negative ions/ml. In general terms, the higher the concentration of negative ions, the fresher the air feels and the better it is for people's health.

Airborne particulates act as condensation nuclei for ions, therefore city air tends to be ion depleted. However, the main losses occur when ion charges are lost within the earthed metal ducts, heat exchangers and grilles of ventilation systems, or through attraction to surfaces such as carpets, furnishing fabrics, ceiling tiles and laminated desk-tops which typically carry a positive static charge. Negative ion levels in
sealed, mechanically ventilated offices typically fall as low as 50 ions/ml, with many naturallyventilated buildings not much better at approximately 250 ions/ml . The only natural parallel can be found immediately prior to a thunderstorm when the earth's field is severely disrupted.

Air processors use a high voltage corona discharge technique to generate negative ions and in their studies, the aim was to maintain minimum concentrations of 2000 neg.ions/ml throughout the trial area. These particular units are 100 per cent free of ozone and nitrous oxides. Negative ions attach themselves to airborne particulates and accelerate the speed with which they settle out. The overall reduction in respirable particulates - both organic and inorganic - is usually in excess of 90 per cent in a busy working environment. Raising the negative ion level also results in the neutralisation of static charges which have been linked to skin rash.

It has long been suggested that negative ions may also exert a lethal effect on microorganisms and recent work by Leeds and Southampton Universities using the same air processors, has confirmed that this does indeed occur with at least some infectious agents and other organisms are slowly being added to the list. Analysis of the results of various studies, found that it was probable that the precipitation of particulates and micro-organisms from the air, together with the biocidal effect account for the high reductions in infection rate.

The researcher's trials attempted to quantify the extent to which short-term exposure to unnaturally low levels of ions and the accompanying high level of particulates typical of many modern working environments, impairs human health and performance and the degree to which this could be economically ameliorated by artificially generated negative ions.

Four of the trial sites belonged to BT and four were studies conducted in the UK premises of other household-name organisations, using the same trial procedures and air processors. It is clear that the studies display a surprising consistency of before and after symptom patterns despite a variety of building structures, air handling systems, interior furnishings and types of activity.

Results to date involve a total of 1,159 subjects and show an overall 57 per cent reduction in reported environmental stress symptoms at work, 59 per cent reduction in the five respiratory stress symptoms and 71 per cent reductions in headaches. The ionisers also made a major contribution to a 38 per cent reduction in general stress symptoms and a reduction in sickness absence in excess of 35 per cent.

They also studied other aspects of performance in the different sites, reflecting the various commercial concerns of the clients. In one call-centre with 124 staff they monitored call response over a nine-month period and found that following their interventions, the number of calls answered per day increased by 3.74 per cent and that the average call handling time was reduced by 1.7 per cent. An additional 4.8 per cent saving derived from the fall in sickness absenteeism. A productivity improvement equivalent to 10.5 additional staff was achieved. Productivity results ranged between 5-15 per cent, the variation, they believe, reflects the commitment of the various executive teams, HR departments and line managers to understand and realise the full productivity potential.

They were also interested to discover whether they could detect any underlying physiology which might indicate how the ions were exerting their influence. During earlier trials involving four companies, they had measured substantial, beneficial changes in the following areas, with no indications of adverse effects:

Blood pressure reduced by 14%
Heart rate reduced by 19%
Muscle tension reduced by 29%
Fatigue (flicker fusion) reduced by 39%
Reaction times reduced by 48%
Grip Ttst increased by 32%
Skin resistance increased by 43%

(These figures support the independent findings that negative air ions have a normalising effect on blood levels of the 'stress' hormone serotonin, on the EEG and the ECG.)

Other significant results from the BT sites were a 30 per reduction in the turnover of new staff during their first 12 months with the company, attributable to ionisation and other environmental improvements.

A trial at Leeds hospital trial demonstrated that air processors can provide a high level of protection against even multi-resistant organisms. The conclusion drawn is that the reductions in coughs, colds and flu-like symptoms achieved in these office studies, were attributable both to the removal of particulates and infectious organisms from the air and to the biocidal action of negative ions.

The conclusion of the researchers is that their work has demonstrated that indoor environments need enhanced levels of negative ions if the occupants are to remain healthy and perform effectively, and that it is in the best interests of every organisation to ensure that such levels are provided and maintained.

... John Jukes, WESTRA (Workplace Environment Science & Technology Research Association); Andrew Jenkins, BT Workstyle; Julian Laws, Air Ion Technologies Ltd, Their research paper, The impact of Improved Air Quality on Productivity and Health in the Workplace, was presented at the Health Building Conference -HB2006 - in Lisbon in June. Copies can be obtained from

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