Table 2.

Significant associations between mortality rates and air pollutant concentrations nationwide and in capital, non-capital, urban, and rural areas

Ischemic heart disease mortality rate
Air pollutant	Nationwide	Capital	Non-capital	Urban	Rural
CO				–
SO2	+	+	+	+	+
NO2			+
O3				+
PM10
Cerebrovascular disease mortality rate
Air pollutant	Nationwide	Capital	Non-capital	Urban	Rural
CO					+
SO2	+	+	+	+
NO2		–	+
O3			–
PM10	+		+		+
Pneumonia mortality rate
Air pollutant	Nationwide	Capital	Non-capital	Urban	Rural
CO
SO2	–
NO2	–	–		–
O3	+			+
PM10	–			–
Chronic Lower Respiratory Disease mortality rate
Air pollutant	Nationwide	Capital	Non-capital	Urban	Rural
CO	–		–	–
SO2					+
NO2	–	–	–	–	+
O3	+	+		+
PM10	–

“+” denotes a positive association, which means increased air pollutant concentrations are associated with higher mortality rates in the study districts

“–” denotes a negative association, which that means the opposite of “+”

Blank denotes null associations

The significance of the associations was determined using 95% confidence intervals