One of the advantages of this data set is that, to our
knowledge, it is the first daily mortality data set compiled
for a city in a tropical climate. Bangkok experiences
a hot and humid climate throughout the year, with 24-
hr average temperatures always above 80 °F. Therefore,
the seasonal weather patterns are very different from
those observed in most previous daily mortality studies.
In addition, the seasonal patterns in mortality are not as
distinct as those found in nontropical climates, where
mortality shows clearly defined peaks in the winter, when
respiratory infections are common, and troughs in the
summer. As a result, seasonality in daily mortality counts
would appear to be less of a potential confounder in this
analysis of daily mortality in Bangkok than in many previous
analyses in which both daily air pollution concentrations
and daily mortality counts have shown distinct
seasonal patterns. In addition, relevant population characteristics
such as smoking habits, occupational exposure,
time spent outdoors, exercise patterns, daily activities,
use of air conditioners, and the provision and use of
medical services may differ in Bangkok relative to the
United States and Western Europe. Therefore, replication
of the previous mortality findings using data from
Bangkok provides an important test of the hypothesis of
an association.