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Table 2 Illustration of the influence of the spatial resolution of the exposure model and of the consideration of data on population density in health impact assessment studies (adapted from [51])

From: The methodology of quantitative risk assessment studies

Hypothesis

PM2.5 exposure: 5th–50th–95th percentiles (µg/m3)

PAF (%) (95% CI)

Number of attributable lung cancer cases (95% CI)

Relative difference compared to main model (%)

Approach 1: population-weighted PM2.5 concentration (main model)

 IRIS scale

8.3 – 13.8 – 21.8

3.6 (1.7–5.4)

1,466 (679–2,193)

–

Sensitivity analyses

Approach 2: population-weighted median PM2.5 concentration

 Department scale

9.7 – 13.8 – 19.1

3.6 (1.7–5.4)

1,471 (680–2,203)

0.4

 Country scale

13.8 – 13.8 – 13.8

3.2 (1.5–4.9)

1,303 (598–1,965)

-11.1

Approach 3: median PM2.5 concentration without population weighing

 Department scale

6.0 – 11.1 – 16.4

2.4 (1.1–3.6)

964 (445–1,446)

-34.2

 Country scale

11.2 – 11.2 – 11.2

1.0 (0.5–1.6)

416 (190–631)

-71.6

Approach 4: alternative RR of lung cancer (1.40 per 10 µg/m3 increase in PM2.5, instead of 1.09)

 Neighbourhood

8.3 – 13.8 – 21.8

12.9 (0.2–25.3)

5,232 (78–10,221)

256.8

  1. The table gives the estimated population attributable fraction (PAF) of lung cancer cases attributable to fine particulate matter (PM2.5) exposure in France among subjects aged 30 years and more, for the year 2015 [51]
  2. In approach 1 (main model), the PAF is estimated using a fine scale PM2.5 dispersion model (2 km grid) at the country level, averaged at the “IRIS” (neighborhood) scale and weighted by population density. In approach 2, exposure is smoothed by assuming that all IRIS of each département have the same PM2.5 concentration (corresponding to the median population-weighted value in each département), or that all départements in the country have the same PM2.5 concentration value (“country scale”). In approach 3, values also correspond to the median value at the département (respectively, country) levels, with the only difference compared to approach 2 that median value are estimated without weighting with population density
  3. Approach 4 differs from approach 1 in that an alternative RR of 1.40 per 10 µg/m3 increase, obtained from a meta-analysis from ESCAPE project including 14 cohorts from eight European countries [52] is used, while a RR of 1.09 is used in model 1 [53]
  4. CI Confidence interval, PAF Population attributable fraction, RR Relative risk
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Environmental Health

ISSN: 1476-069X