Ambient Air Quality – PAHO/WHO | Pan American Health Organization
Table 1 – Total number of towns and cities in WHO AAP database in 2016, by income groups in the Americas
Number of towns and cities
Number of countries
Number of countries in region
America, LMI
102
13
24
America, HI
524
6
11
AAP = Ambient Air Pollution; LMI = Low and Middle Income countries; HI = High income countries. Source: WHO, 2016.
In LAC, only 24 out of 43 cities with one million or more inhabitants have measurements of PM10 (56%), and only 16 for PM2.5 (37%). Table 2 shows the distribution of the cities with monitoring sites for fine particles in LAC according to population size (Riojas etal., 2016); Table 3 shows the WHO guidelines for Ambient Air pollution (WHO AQG) and Table 4 shows the compliance with WHO AQG for annual median exposure levels of fine particles in these cities (Riojas etal., 2016).
Table 2 – Number of cities in LAC (?100 000) with ground level monitoring sites of fine particles (PM10 and PM2.5)
City population size
Number of cities
PM10
PM2.5
100.000 – 500.000
463
66
35
500.000 – 1.000.000
58
14
6
1.000.000 – 5.000.000
35
16
9
5.000.000 – 10.000.000
5
5
5
10.000.000
3
3
2
TOTAL
564
104
57
Table 3– WHO Air Quality Guidelines
PM10 (µg/m3)
PM2.5 (µg/m3)
IT- 1
70
35
15% higher long term mortality risk relative to AQG levels
IT- 2
50
25
6% lower long term mortality risk relative to Tier 1
IT- 3
30
15
6% lower long term mortality risk relative to Tier 2
WHO AQG
20
10
Lower level at which health risks have shown to increase in response of long term exposure to PM2.5
Table 4– Compliance with WHO AQG for annual median exposure levels of fine particles in LAC cities with 100 000 inhabitants or more with ground level monitoring sites of fine particles (PM10 and PM2.5).
No compliance
IT-1
IT-2
IT-3
WHO AQG
TOTAL
PM10
9
20
46
24
5
104
PM2.5
7
12
25
9
4
57
When comparing compliance with WHO AQG between HI and LMI countries in the Americas, more than 80% of the towns and cities assessed in HI are below the guidelines, while less than 10% of them in LMI were below the guidelines. Figure 1 show the distribution of the modelled PM2.5, where the concentration of air pollutants is clearly higher in LMI countries. For additional information on the methodology for modelling PM2.5 see: Ambient air pollution: A global assessment of exposure and burden of disease (WHO, GBoD 2016).
Figure 1: Modelled levels of PM2.5, Region of the Americas. Source: WHO Global air pollution data portal.
