View source for I. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021

The 2021 WHO air quality guidelines encompass a comprehensive framework applicable to both outdoor and indoor environments, covering various settings where people spend their time<sup><small>107</small></sup>. While these guidelines extend to numerous contexts, they do not address occupational settings due to unique exposure characteristics and risk reduction policies, along with potential differences in population susceptibility within the adult workforce<sup><small>108</small></sup>.

The primary objective of these updated global guidelines is to provide evidence-based quantitative recommendations for air quality management, offering long- or short-term concentration values for key air pollutants. Exceeding the air quality guideline levels is linked to significant public health risks. Although not legally binding standards, these guidelines equip World Health Organisation member states with an evidence-driven tool to shape legislation and policies, with the ultimate aim of reducing air pollutant levels and alleviating the substantial global health burden from air pollution exposure<sup><small>109</small></sup>. 

''' Table 2: Recommended AQG levels and interim targets''' (Extracted from WHO IAQ Guidelines 2010)
{| class="wikitable"
| rowspan="2" |'''Pollutant'''
| rowspan="2" |'''Averaging time'''
| colspan="4" |'''Interim target'''
| rowspan="2" |'''AQG level'''
|-
|'''1'''
|'''2'''
|'''3'''
|'''4'''
|-
| rowspan="2" |PM2.5, µg/m3 

|Annual
|35
|25
|15  
|10
|5
|-
|24-hour[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn1|<sup>[1]</sup>]]
|75
|50
|37.5
|25
|15
|-
| rowspan="2" |PM10,  µg/m3 
|Annual
|70
|50
|30
|20
|15
|-
|24-hour[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn2|<sup>[2]</sup>]]
|150
|100
|75
|50
|45
|-
| rowspan="2" |O3, µg/m3     
|Peak season[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn3|<sup>[3]</sup>]]
|100
|70
|–
|–
|60
|-
|8-hour[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn4|<sup>[4]</sup>]]
|160
|120
|–
|–
|100
|-
| rowspan="2" |NO2, µg/m3   
|Annual
|40
|30
|20
|–
|10
|-
|24-hour[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn5|<sup>[5]</sup>]]
|120
|50
|–
|–
|25
|-
|SO2,  µg/m3
|24-hour[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn6|<sup>[6]</sup>]]
|125
|50
|–
|–
|40
|-
|CO, mg/m3
|24-hour[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftn7|<sup>[7]</sup>]]
|7
|–
|–
|–
|4
|}
----[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref1|[1]]] 99th percentile (i.e. 3–4 exceedance days per year).

[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref2|[2]]] 99th percentile (i.e. 3–4 exceedance days per year).

[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref3|[3]]] Average of daily maximum 8-hour mean O3 concentration in the six consecutive months with the highest six-month running-average O3 concentration.

[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref4|[4]]] 99th percentile (i.e. 3–4 exceedance days per year).

[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref5|[5]]] 99th percentile (i.e. 3–4 exceedance days per year).

[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref6|[6]]] 99th percentile (i.e. 3–4 exceedance days per year).

[[9. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide – 2021#%20ftnref7|[7]]] 99th percentile (i.e. 3–4 exceedance days per year).


RL14: Table 0.2. Air quality guidelines for nitrogen dioxide, sulfur dioxide and carbon monoxide (short averaging times) that were not re-evaluated and remain valid (WHO, 2021)
{| class="wikitable"
|'''Pollutant''' 
|'''Averaging time'''
|'''Air quality guidelines that  remain valid'''
|-
|NO2, µg/m3 1-hour 200
|1-hour
|200
|-
|SO2, µg/m3 10-minute 500
|10-minute 
|500
|-
| rowspan="3" |CO, mg/m3 

|8-hour
|10
|-
|1-hour
|35
|-
|15-minute
|100
|}

=== ''' References ''' ===

107 The World Health Organisation, “WHO Global Air Quality Guidelines,” the World Health Organisation, 2021. Available online: https://apps.who.int/iris/bitstream/handle/10665/345334/9789240034433-eng.pdf?sequence=1&isAllowed=y

108 The World Health Organisation, “WHO Global Air Quality Guidelines,” the World Health Organisation, 2021. Available online: https://apps.who.int/iris/bitstream/handle/10665/345334/9789240034433-eng.pdf?sequence=1&isAllowed=y

109 The World Health Organisation, “WHO Global Air Quality Guidelines,” the World Health Organisation, 2021. Available online: https://apps.who.int/iris/bitstream/handle/10665/345334/9789240034433-eng.pdf?sequence=1&isAllowed=y
[[Category: IAQ Policy Landscape]]