A study of the reliability on the passive sampler in the tropical area has been made by simultaneous determinations of the passive sampler (improved Amaya) and Filter Badge NO
2and the active sampler in April, 2000 during a dry season on Visayas Road, Quezon City, Philippine.
As the result, its external temperature was 33°C on average, and the relative humidity was 49% on average, not showing high humidity as expected. The NO
2and NO concentrations were in the ranges of 41 to 98 ppb, and 33 to 329 ppb, respectively, and the contribution ratio of moving and generation source NO×100/NOx was 60 to 7000, from April 10 to April 12, 2000. From the comparison of the results for the passive sampler with those for the active sampler, the coefficient (β) for concentration conversion is calculated to be:
β=5 for Amaya-sampler, β=71 for Filter-Badge NO
2The concentration of NO
2, (24 hours exposure) from April 24 to 28 was 36 to 56 ppm in the land estate owned by Department of Environmental Natural Resources (DENR) facing Visayas Road obtained by using the coefficient for concentration conversion. This concentration of NO
2measured by the passive sampler was 35% higher than the average concentration determined on December, 1997 at the same place.
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