Experiments

Experiments

health and productivity

At the “Healthy Buildings” conference (Espoo, Finland), Dr. David Wyon, presented a paper titled “The effects on health and self-estimated productivity of two experimental interventions which reduced airborne dust levels in office premises”. Below is a short summary of their findings. Their conclusion is that better supply-air filtration and more frequent filter changes would have a positive effect on health and productivity in offices.

An earlier field study succeeded in showing that intensive office cleaning leads to reduced exposure to airborne dust, but did not examine the possible impact on health, comfort or productivity. Another study reported that mucus membrane symptoms of the eye, nose and throat were significantly reduced by thorough cleaning of offices, and that improved cleaning significantly reduced nasal airways congestion.

In a U.S. study replacing conventional office supply-air filters with high efficiency air filters (95% for 0.3 μm particles) reduced airborne dust levels in size ranges above PM2 and had a positive effect on three Sick Building Syndrome (SBS) symptoms: “too stuffy”, “too humid” and “mental confusion”.

These results justify the claim that other methods of reducing dust exposure, such as choice of materials, closed shelves, better supply-air filtration, more supply air or free-standing air cleaners may have a positive effect on health.

London office experiment

The London experiment was performed to determine whether changing prefilters or operating air cleaners would affect health and productivity.

Over an 18-week period, airborne dust levels in a central London office were altered by replacing well-used supply-air prefilters (P-filters) with new ones and operating free-standing electrostatic filters (E-filters).

     
 

Conclusion

Changing supply air prefilters in the office building significantly reduced the intensity of several SBS symptoms and increased self-estimated productivity by 5.7%.

Consequently, there seems little doubt that better supply-air filtration and more frequent filter changes would have a positive effect both on health and on productivity.

The size of the latter effect alone is sufficient to justify many times over the increased economic costs associated with these improvements in IAQ.

"Supply-air filtration improves IAQ without increasing the air change rate: energy costs increase only to the extent that increased fan power is required to overcome the pressure drop at the filter, and this is decreased by more frequent filter changes”, Dr. Wyon says.

 
     

 

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