A study of personal exposure to nitrogen dioxide using passive samplers

A group of 60 people from an age of 22 to 45 was selected for a study of their personal exposure to nitrogen dioxide (NO₂). All the participants were selected from the group of people who spent most of their time at home and in an air-conditioned office environment, which also represented the majority of the people in the population. Among this group of participants, 12 were selected to participate in a more detailed investigation on the NO₂ levels in various locations in their home environment. It was found that the average personal exposure to NO₂ of the 60 participants was 46.0 μg/m³, which was quite close to the average level of 47.3 μg/m³ of the 12 participants who were involved in the measurement exercises in their home environment. The 12 residential premises were studied for NO₂ levels in different locations in both the indoor environment and the surrounding outdoor environment. It was found that the average NO₂ level in the indoor environment (living room, bedroom and kitchen) was 55.2 μg/m³ while the corresponding outdoor NO₂ level was 71.8 μg/m³. The study indicated that cooking activities in the kitchen had strong impact on the NO₂ level. When cooking existed, the average indoor NO₂ level was 59.7 μg/m³ and when cooking did not exist, the NO₂ level was 41.8 μg/m³. Average indoor to outdoor NO₂ ratio was 0.80. The study indicated that the home environment showed the highest impact to the total personal NO₂ exposure due to the relatively higher NO₂ level caused by combustion effect in the kitchen as well as the long time period spent every day in this micro environment. NO₂ level in an air-conditioned office was low and the impact from other outdoor sources was not significant due to the small amount of time spent in those micro-environments even though in some occasions the instantaneous levels would be high.