Pollution source control and ventilation improve health, comfort and productivity

Control of indoor pollution sources and ventilation are both means of improving indoor air quality. Three independent experiments have recently documented that removing a pollution source or increasing the ventilation rate will improve perceived air quality, reduce the intensity of several Sick Building Syndrome (SBS) symptoms and improve the productivity of office workers. In these experiments, the performance of simulated office work (text typing, addition and proof-reading, all typical office tasks requiring concentration) improved monotonically as the proportion dissatisfied with the air quality was reduced by either measure. The quantitative relationship was 1.1 % change in performance per 10% dissatisfied, in the range 25-70% dissatisfied, or 0.5% change in performance per 1 decipol (dp), in the range 2- 13 dp. Significant performance improvements occurred only when the intensity of general SBS symptoms such as headache and difficulty in thinking clearly were significantly reduced, which implies that this was the mechanism of causation. The performance of simulated office work increased monotonically with decreasing pollution load, a 1.6% increase in performance for each two-fold decrease of pollution load in the range 0.3-2 olf/m2floor, and with increasing outdoor air supply rate, a 1.8% increase in performance for each two-fold increase in the outdoor air supply rate in the range 0.8-5.3 Lis per olf. As these results clearly justify increased initial and operating· costs; future developments in HVAC technology may include "personalized air", new ways of improving the quality of supply air (e.g., by filtration), more extensive use of heat recovery from exhaust air and systematic selection of low-polluting building and furnishing materials.