The APHEA2 mortality study covered a population of more than 43 million living in 29
European cities, which were all studied for > 5 years in the early-mid 1990s.

The APHEA2 hospital admission study covered a population of 38 million living in 8 European cities, which where studied for 3 to 9 years in the early-mid 1990s.

The NMMAPS mortality study covered a population of more than 50 million living in 20 metropolitan areas in the United States of America, which were all studied over the 1987–1994 period.

The NMMAPS hospital admission study covered 10 large metropolitan areas in the United States of America with a combined population of 1 843 000 subjects over 65 years old.”

Source: WHO Regional Office for Europe  "Health Aspects of Air Pollution" (2003)
Chapter 5, Particulate matter (PM) Section 5.2 Answers and rationales, Question 9

Air Pollution Particulate Matter

Table 1. Estimated effects of air pollution on daily mortality and hospital admissions from APHEA2 and NMMAPS studies

Table 2. Summary of time series relating coarse particulate matter to mortality

Figure 1. Direct Release of Particles

Figure 2. Indirect Formation of Particles

Figure 4. Modelled deposition of particles in the human respiratory tract using the MPPD (Price et al., 2002) model

Fig. 1: Funnel plot of black smoke and "daily all cause mortality" in 47 studies.

Table 1. Summary estimates for studies of PM10 and daily mortality by GAM or non-GAM statistical model and by single-city or multicity study design.