Formaldehyde exposure risk in air-conditioned offices of Hong Kong

Formaldehyde (HCHO) is a carcinogenic toxicant commonly present in an air-conditioned office environment. This study examines the lifetime exposure risk of HCHO in air-conditioned offices of Hong Kong under various indoor environmental conditions. Using the regional indoor air quality assessment results of 511 Hong Kong offices recorded from 1996 to 2005, together with the mathematical correlations among HCHO exposure concentration, ventilation and thermal environment verified at 43 other local air-conditioned offices, the exposure risk in terms of loss of life expectancy (USEPA standard) was predicted for an office environment preset at certain air temperature and atmospheric carbon dioxide (CO2) level. It was reported that the average increment of HCHO exposure risk was 2% for every 1°C increment in the air temperature range of 22.5-25.5°C, or 2.5% for every 10 ppm increment in the CO2concentration range of 800-1000 ppm. This study presents useful information on HCHO exposure risk evaluation for air-conditioned offices associated with various policies on indoor air temperature and ventilation demands. Practical applications: This studyoutlines an approach to lifetime exposure risk assessment for HCHO inhaled in air-conditioned offices of Hong Kong under various indoor environmental conditions. In a typical office environment, the findings demonstrated that the average increment of HCHO exposure risk was 2% for every 1°C increment in air temperature or 2.5% for every 10 ppm increment in CO2concentration.