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. 2008 Oct 30;105(44):16860–16865. doi: 10.1073/pnas.0808927105

Table 2.

Risk factors analyzed in this article, their exposure metrics, alternative exposure levels, disease outcomes, and data sources for relative risks and exposures (19, 24, 25)

Risk factor Exposure metric Sources for exposure data Alternative exposure Disease outcomes affected Sources for relative risks
Unsafe water and sanitation Four categories of water and sanitation access (Table S4) 2005 Census Access to piped water and a flush toilet in all homes Diarrheal disease Systematic reviews of multicountry randomized controlled trials and observational studies (25)
Urban PM pollution Average annual concentration of PM10 and PM2.5* Municipal air quality monitoring systems, Global Model of Ambient Particulates (GMAPS) Annual average PM10 concentration of 15 μg/m3 and PM2.5 concentration of 7.5 μg/m3 Acute respiratory infections in children <5 y old; lung cancer and cardiopulmonary diseases in adults ≥30 y old Systematic review of cohort studies (19, 26)
Indoor air pollution from household solid fuel use Household solid fuel use 2000 Census, 2005 Encuesta Nacional de Salud y Nutrición No household solid fuel use Acute lower-respiratory infections in children <5 y old; chronic obstructive pulmonary disease in adults ≥30 y old Systematic review and meta-analysis of cross-sectional, cohort and case-control studies (24)

See Table S5 for relative risks.

*PM with an aerodynamic diameter of ≤10 μm and ≤2.5 μm, respectively.

Validated annual concentration data for PM10 are available for 8 cities and for PM2.5 for only Mexico City (9). We used measured PM10 concentrations for these cities. We used PM2.5/PM10 ratios of 0.5 for cities in the central area of Mexico based on monitoring in Mexico City, 0.32 for Monterrey from early monitoring data, and 0.25 from measurements in Ciudad Juarez for the cities in the U.S. border to calculate annual average PM2.5 concentration (9, 27). For other cities with population >100,000, we used the estimated PM10 and PM2.5 concentrations from GMAPS, an energy and economic model developed at the World Bank (19). In the main analysis, we assumed that the remaining rural population was not exposed to urban PM pollution.

For urban PM, although there is no clear threshold below which there are no effects on health, we used an alternative scenario of 15 μg/m3 PM10 or 7.5 μg/m3 PM2.5, based on the lowest concentration at which health benefits were observed in cohort studies (19, 28).

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