REPORT-COVID-19-Impact-on-Air-Quality-in-10-Major-Cities_V6.pdf
Media
Part of COVID-19 Air Quality Report by IQAir
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COVID-19
AIR QUALITY
REPORT
2019 coronavirus
pandemic lockdowns
result in unprecedented
reductions in deadly
particle pollution
Publication date: Apr. 22, 2020
About this report
As lockdowns were implemented in response to the deadly coronavirus pandemic, the
dramatic changes brought about by these restrictions have been described as the ‘largest
scale experiment ever’ into air quality.1
Coinciding with the
50th anniversary of
Earth Day, this report
investigates the impact
COVID-19 lockdowns
have had on global
particulate pollution
levels
In many places, the halt of movement and industry has
shown a glimpse of a cleaner world, with many reports
of exceptional blue skies. However, visual perception
alone can be deceiving when observing air pollution. This
report compares measurements of the world’s deadliest air
pollutant, fine particulate matter (PM2.5), prior to and
during the pandemic in 10 major global cities under lockdown: Delhi, London, Los Angeles, Milan, Mumbai, New
York City, Rome, São Paulo, Seoul and Wuhan. Findings
reveal a drastic drop in PM2.5 pollution for most global
locations under lockdown conditions.
These findings coincide with the 50th anniversary of Earth Day, whose theme this year is
climate action. While ground-level air pollution poses our greatest environmental health hazard today, many sources of PM2.5 pollution - such as fossil fuel combustion - also contribute
to climate change.
1
2 |
https://le.ac.uk/news/2020/march/24-largest-experiment
https://www.iqair.com
Methodology
This report analyzes levels of PM2.5 reported by ground-level monitoring stations in 10
major global cities.
The data is based on a 3-week period for each city during lockdown conditions, and compares
this to the same time period in 2019, 2018, 2017 and 2016.
The same time period across different years was chosen, because air pollution levels often
vary greatly with seasonal changes in weather and other conditions.
The 3-week timeframe has been selected for each city to reflect either the period when the
most stringent lockdown measures were in place or, during longer lockdown periods such
as in Wuhan, to coincide with the ‘peak’ of daily reported COVID-19 cases.
Cities were selected based on the extent of lockdown measures and the number of coronavirus
cases relative to other cities in the same country. The methodology and data representation
strives to highlight the effects of the COVID-19 lockdowns on a wide variety of cities with
different air quality challenges.
How the data is collected
This report uses hourly PM2.5 readings recorded by 7 governmental agencies: the U.S. State
Department, China National Environment Monitoring Center, European Environment Agency, Seoul Metropolitan Government, Companhia Ambiental do Estado de São Paulo, and
Ayuntamiento de Madrid. Supplemental data has been obtained from validated non-governmental air quality monitoring stations.
All locations and their data sources are visible on the IQAir AirVisual app and website:
https://www.iqair.com/air-quality-map.
How the data is presented
In order to correlate concentration values to a more relatable reference for health risk, this report uses the
US EPA standard color index, supplemented by the WHO annual mean exposure threshold of 10 µg/m³.1,2
PM2.5
(µg/m³)
Level of
Concern
1
2
3 |
12.0
WHO
Good
Guideline
35.4
Moderate
55.4
Unhealthy for Sensitive
Groups
150.4
Unhealthy
250.4
Very Unhealthy
Hazardous
https://www.airnow.gov/aqi/aqi-basics/
https://www.who.int/airpollution/publications/aqg2005/en/
https://www.iqair.com
Summary
• 9 of 10 key global cities experienced PM2.5 reductions from the same period in
2019
• Cities with historically higher levels of PM2.5 pollution witnessed the most substantial
drops, including Delhi (-60%), Seoul (-54%) and Wuhan (-44%)
• During Wuhan’s 10-week lockdown, the city experienced its cleanest February and
March air quality on record
• Delhi’s ‘unhealthy’ and worse rated hours plummeted from 68% in 2019 to 17% during the
lockdown period1
• Los Angeles experienced its longest stretch of clean air on record meeting the WHO
air quality guidelines
Average PM2.5
during lockdown
2020 (µg/m³)
Reduction
compared to
2019
Reduction
compared with prior
4 year average
3-week lockdown dates,
2020
Delhi, India
32.8
-60%
-55%
Mar 23 - Apr 13
London, UK
16.2
-9%
+6%
Mar 23 - Apr 13
Los Angeles, US
5.5
-31%
-51%
Mar 23 - Apr 13
Madrid, Spain
6.4
-11%
+2%
Mar 23 - Apr 13
Mumbai, India
28.8
-34%
-43%
Mar 23 - Apr 13
New York City, US
4.4
-25%
-29%
Mar 23 - Apr 13
Rome, Italy
16.7
+30%
No data available
Mar 9 - Mar 30
São Paulo, Brazil
10.1
-32%
-26%**
Mar 23 - Apr 13
Seoul, South Korea
24.1
-54%
-32%
Feb 26 - Mar 18
Wuhan, China
35.1
-44%
-50%
3 Feb - Feb 24
City
** Data for São Paulo is based on a 3-year average, rather than a 4-year average
PM2.5
(µg/m³)
WHO
10.0 12.0
PM2.5 Guideline 12.0
(µg/m³)
WHO
Level of
Good
Concern Guideline
1
4 |
Moderate
35.4
55.4
35.4
55.4
Unhealthy for Sensitive
Groups
150.4
150.4
Unhealthy
250.4
250.4
Very Unhealthy Hazardous
According to the US Air Quality Index
https://www.iqair.com
Global Findings
9 of 10 key global cities experienced PM2.5 reductions from
the same period in 2019
Ten major global cities have been studied in this report for their relatively high number of
coronavirus cases and government-mandated COVID-19 lockdown measures.
In 7 of these identified cities, drastic restrictions on people’s movement and economic
activity imposed during lockdowns resulted in PM2.5 reductions of 25-60%, as compared to the
same time period last year.1
Map 1: Percent reduction in PM2.5 levels when comparing 2020 lockdown period to the same period in 2019
1
PM2.5 (Particulate matter with a diameter of 2.5 micrometers or less) is widely regarded as the pollutant that poses the greatest threat to health of all
commonly measured air pollutants. Due to its small size, PM2.5 is able to penetrate deep into the human respiratory system and into the blood stream,
potentially causing a wide range of short- and long-term health effects. For more information, go to https://www.iqair.com/blog/air-quality/pm2-5
5 |
https://www.iqair.com
Cities with historically higher levels of PM2.5 pollution witnessed the
most substantial drops, including Delhi (-60%), Seoul (-54%) and
Wuhan (-44%)
While all cities demonstrated a drop in PM2.5 levels during lockdown conditions when compared to
2019, cities with historically higher PM2.5 concentration levels, such as Delhi, Mumbai, and Wuhan,
showed the most dramatic reductions in PM2.5.
Graph 1: Yearly PM2.5 levels over defined 3-week period for selected major cities
6 |
https://www.iqair.com
Wuhan, China
Wuhan saw a 50% reduction in PM2.5 during the 2020 COVID-19
lockdown, as compared to the previous 4-year period average
LOCKDOWN MEASURES
Wuhan, the epicenter of the original novel coronavirus outbreak, had some of the highest numbers of reported
COVID-19 cases globally. In response to a surge of cases and deaths, the Chinese government ordered its highest
Class 1 Response for public health emergencies on January 24.1
Wuhan’s lockdown directives on its 11 million residents were the most stringent and long-lasting of anywhere globally.
After 10 weeks of far-reaching mitigation efforts, the city’s lockdown was finally lifted on April 8.2
Wuhan’s lockdown measures included barring private vehicle movement, a suspension of most public transport,
school closures, and the shutdown of all non-essential businesses.3,4 Some areas restricted outings to one family
member every other day to buy necessities. Areas under containment barred residents from leaving, requiring them
to order in food and other supplies from delivery services.
IMPACT ON PM2.5
Over the course of Wuhan’s full 10-week lockdown, the city experienced its cleanest air quality on record for the
months of February and March, with average PM2.5 concentrations (µg/m³) of 36.8 and 32.9 respectively. For context, February and March 2019 averaged PM2.5 concentrations of 63.2 and 43.9 respectively.
Graph 2: Daily PM2.5 levels in Wuhan from 2016-2020, indicated by US AQI color
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
2016
2017
2018
2019
PM2.5
(µg/m³)
2020
Wuhan lockdown
1
2
3
4
7 |
Level of
Concern
WHO
10.0 12.0
PM2.5 Guideline 12.0
(µg/m³)
WHO
Guideline
Good
Moderate
35.4
55.4
35.4
55.4
Unhealthy for Sensitive
Groups
150.4
150.4
Unhealthy
250.4
250.4
Very Unhealthy Hazardous
Details of Class 1 Response for public health emergencies: http://china.caixin.com/2020-01-29/101509411.html
The 3-week time frame used in this report (February 3 - February 24) highlights the ‘peak’ of the curve when Wuhan was reporting the most new daily cases.
https://www.theguardian.com/world/2020/mar/19/chinas-coronavirus-lockdown-strategy-brutal-but-effective#maincontent
Essential businesses only included those relating to food, medicine and healthcare.
https://www.iqair.com
During the defined 3-week peak lockdown period, PM2.5 levels in Wuhan were slashed to half the average of the prior
4 years, and were down 44% from 2019. The smaller decrease since 2019 indicates the Chinese government’s
ongoing efforts to reduce air pollution across major Chinese cities year-on-year.
Graph 3: Daily PM2.5 levels in Wuhan from 2016-2020 (Feb 3 - Feb 24)
During the past 4 years, between February 3 and February 24, 50-60% of hours qualified as “unhealthy” or “very
unhealthy” according to the US Air Quality Index (AQI).1,2 For the same period in 2020, only 22% of hours were classified as US AQI “unhealthy”. Moreover, 2020’s period had 7.5% of hours meet the stringent WHO target for PM2.5
levels (
AIR QUALITY
REPORT
2019 coronavirus
pandemic lockdowns
result in unprecedented
reductions in deadly
particle pollution
Publication date: Apr. 22, 2020
About this report
As lockdowns were implemented in response to the deadly coronavirus pandemic, the
dramatic changes brought about by these restrictions have been described as the ‘largest
scale experiment ever’ into air quality.1
Coinciding with the
50th anniversary of
Earth Day, this report
investigates the impact
COVID-19 lockdowns
have had on global
particulate pollution
levels
In many places, the halt of movement and industry has
shown a glimpse of a cleaner world, with many reports
of exceptional blue skies. However, visual perception
alone can be deceiving when observing air pollution. This
report compares measurements of the world’s deadliest air
pollutant, fine particulate matter (PM2.5), prior to and
during the pandemic in 10 major global cities under lockdown: Delhi, London, Los Angeles, Milan, Mumbai, New
York City, Rome, São Paulo, Seoul and Wuhan. Findings
reveal a drastic drop in PM2.5 pollution for most global
locations under lockdown conditions.
These findings coincide with the 50th anniversary of Earth Day, whose theme this year is
climate action. While ground-level air pollution poses our greatest environmental health hazard today, many sources of PM2.5 pollution - such as fossil fuel combustion - also contribute
to climate change.
1
2 |
https://le.ac.uk/news/2020/march/24-largest-experiment
https://www.iqair.com
Methodology
This report analyzes levels of PM2.5 reported by ground-level monitoring stations in 10
major global cities.
The data is based on a 3-week period for each city during lockdown conditions, and compares
this to the same time period in 2019, 2018, 2017 and 2016.
The same time period across different years was chosen, because air pollution levels often
vary greatly with seasonal changes in weather and other conditions.
The 3-week timeframe has been selected for each city to reflect either the period when the
most stringent lockdown measures were in place or, during longer lockdown periods such
as in Wuhan, to coincide with the ‘peak’ of daily reported COVID-19 cases.
Cities were selected based on the extent of lockdown measures and the number of coronavirus
cases relative to other cities in the same country. The methodology and data representation
strives to highlight the effects of the COVID-19 lockdowns on a wide variety of cities with
different air quality challenges.
How the data is collected
This report uses hourly PM2.5 readings recorded by 7 governmental agencies: the U.S. State
Department, China National Environment Monitoring Center, European Environment Agency, Seoul Metropolitan Government, Companhia Ambiental do Estado de São Paulo, and
Ayuntamiento de Madrid. Supplemental data has been obtained from validated non-governmental air quality monitoring stations.
All locations and their data sources are visible on the IQAir AirVisual app and website:
https://www.iqair.com/air-quality-map.
How the data is presented
In order to correlate concentration values to a more relatable reference for health risk, this report uses the
US EPA standard color index, supplemented by the WHO annual mean exposure threshold of 10 µg/m³.1,2
PM2.5
(µg/m³)
Level of
Concern
1
2
3 |
12.0
WHO
Good
Guideline
35.4
Moderate
55.4
Unhealthy for Sensitive
Groups
150.4
Unhealthy
250.4
Very Unhealthy
Hazardous
https://www.airnow.gov/aqi/aqi-basics/
https://www.who.int/airpollution/publications/aqg2005/en/
https://www.iqair.com
Summary
• 9 of 10 key global cities experienced PM2.5 reductions from the same period in
2019
• Cities with historically higher levels of PM2.5 pollution witnessed the most substantial
drops, including Delhi (-60%), Seoul (-54%) and Wuhan (-44%)
• During Wuhan’s 10-week lockdown, the city experienced its cleanest February and
March air quality on record
• Delhi’s ‘unhealthy’ and worse rated hours plummeted from 68% in 2019 to 17% during the
lockdown period1
• Los Angeles experienced its longest stretch of clean air on record meeting the WHO
air quality guidelines
Average PM2.5
during lockdown
2020 (µg/m³)
Reduction
compared to
2019
Reduction
compared with prior
4 year average
3-week lockdown dates,
2020
Delhi, India
32.8
-60%
-55%
Mar 23 - Apr 13
London, UK
16.2
-9%
+6%
Mar 23 - Apr 13
Los Angeles, US
5.5
-31%
-51%
Mar 23 - Apr 13
Madrid, Spain
6.4
-11%
+2%
Mar 23 - Apr 13
Mumbai, India
28.8
-34%
-43%
Mar 23 - Apr 13
New York City, US
4.4
-25%
-29%
Mar 23 - Apr 13
Rome, Italy
16.7
+30%
No data available
Mar 9 - Mar 30
São Paulo, Brazil
10.1
-32%
-26%**
Mar 23 - Apr 13
Seoul, South Korea
24.1
-54%
-32%
Feb 26 - Mar 18
Wuhan, China
35.1
-44%
-50%
3 Feb - Feb 24
City
** Data for São Paulo is based on a 3-year average, rather than a 4-year average
PM2.5
(µg/m³)
WHO
10.0 12.0
PM2.5 Guideline 12.0
(µg/m³)
WHO
Level of
Good
Concern Guideline
1
4 |
Moderate
35.4
55.4
35.4
55.4
Unhealthy for Sensitive
Groups
150.4
150.4
Unhealthy
250.4
250.4
Very Unhealthy Hazardous
According to the US Air Quality Index
https://www.iqair.com
Global Findings
9 of 10 key global cities experienced PM2.5 reductions from
the same period in 2019
Ten major global cities have been studied in this report for their relatively high number of
coronavirus cases and government-mandated COVID-19 lockdown measures.
In 7 of these identified cities, drastic restrictions on people’s movement and economic
activity imposed during lockdowns resulted in PM2.5 reductions of 25-60%, as compared to the
same time period last year.1
Map 1: Percent reduction in PM2.5 levels when comparing 2020 lockdown period to the same period in 2019
1
PM2.5 (Particulate matter with a diameter of 2.5 micrometers or less) is widely regarded as the pollutant that poses the greatest threat to health of all
commonly measured air pollutants. Due to its small size, PM2.5 is able to penetrate deep into the human respiratory system and into the blood stream,
potentially causing a wide range of short- and long-term health effects. For more information, go to https://www.iqair.com/blog/air-quality/pm2-5
5 |
https://www.iqair.com
Cities with historically higher levels of PM2.5 pollution witnessed the
most substantial drops, including Delhi (-60%), Seoul (-54%) and
Wuhan (-44%)
While all cities demonstrated a drop in PM2.5 levels during lockdown conditions when compared to
2019, cities with historically higher PM2.5 concentration levels, such as Delhi, Mumbai, and Wuhan,
showed the most dramatic reductions in PM2.5.
Graph 1: Yearly PM2.5 levels over defined 3-week period for selected major cities
6 |
https://www.iqair.com
Wuhan, China
Wuhan saw a 50% reduction in PM2.5 during the 2020 COVID-19
lockdown, as compared to the previous 4-year period average
LOCKDOWN MEASURES
Wuhan, the epicenter of the original novel coronavirus outbreak, had some of the highest numbers of reported
COVID-19 cases globally. In response to a surge of cases and deaths, the Chinese government ordered its highest
Class 1 Response for public health emergencies on January 24.1
Wuhan’s lockdown directives on its 11 million residents were the most stringent and long-lasting of anywhere globally.
After 10 weeks of far-reaching mitigation efforts, the city’s lockdown was finally lifted on April 8.2
Wuhan’s lockdown measures included barring private vehicle movement, a suspension of most public transport,
school closures, and the shutdown of all non-essential businesses.3,4 Some areas restricted outings to one family
member every other day to buy necessities. Areas under containment barred residents from leaving, requiring them
to order in food and other supplies from delivery services.
IMPACT ON PM2.5
Over the course of Wuhan’s full 10-week lockdown, the city experienced its cleanest air quality on record for the
months of February and March, with average PM2.5 concentrations (µg/m³) of 36.8 and 32.9 respectively. For context, February and March 2019 averaged PM2.5 concentrations of 63.2 and 43.9 respectively.
Graph 2: Daily PM2.5 levels in Wuhan from 2016-2020, indicated by US AQI color
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
2016
2017
2018
2019
PM2.5
(µg/m³)
2020
Wuhan lockdown
1
2
3
4
7 |
Level of
Concern
WHO
10.0 12.0
PM2.5 Guideline 12.0
(µg/m³)
WHO
Guideline
Good
Moderate
35.4
55.4
35.4
55.4
Unhealthy for Sensitive
Groups
150.4
150.4
Unhealthy
250.4
250.4
Very Unhealthy Hazardous
Details of Class 1 Response for public health emergencies: http://china.caixin.com/2020-01-29/101509411.html
The 3-week time frame used in this report (February 3 - February 24) highlights the ‘peak’ of the curve when Wuhan was reporting the most new daily cases.
https://www.theguardian.com/world/2020/mar/19/chinas-coronavirus-lockdown-strategy-brutal-but-effective#maincontent
Essential businesses only included those relating to food, medicine and healthcare.
https://www.iqair.com
During the defined 3-week peak lockdown period, PM2.5 levels in Wuhan were slashed to half the average of the prior
4 years, and were down 44% from 2019. The smaller decrease since 2019 indicates the Chinese government’s
ongoing efforts to reduce air pollution across major Chinese cities year-on-year.
Graph 3: Daily PM2.5 levels in Wuhan from 2016-2020 (Feb 3 - Feb 24)
During the past 4 years, between February 3 and February 24, 50-60% of hours qualified as “unhealthy” or “very
unhealthy” according to the US Air Quality Index (AQI).1,2 For the same period in 2020, only 22% of hours were classified as US AQI “unhealthy”. Moreover, 2020’s period had 7.5% of hours meet the stringent WHO target for PM2.5
levels (
Accrual Method (Dublin Core)
2317