Impact of Air Pollution on Human Health

Why in news?

Recently, the State of Global Air (SoGA) 2024 was released which offers a stark reminder of the significant impacts air pollution has on human health.

What is air pollution?

Air pollution – It is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere.
Common sources – Household combustion devices, motor vehicles, industrial facilities and forest fires are common sources of air pollution.
The major outdoor pollution sources include residential energy for cooking and heating, vehicles, power generation, agriculture/waste incineration, and industry.
Pollutants - Pollutants of major public health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide.
Impact on climate – Many of the drivers of air pollution (i.e. combustion of fossil fuels) are also sources of greenhouse gas emissions.
Impact on human health - Outdoor and indoor air pollution cause respiratory and other diseases and are important sources of morbidity and mortality.
Polluted air is a big trigger for pneumonia and other respiratory infections and allergic diseases in children.
There is a strong connection between long-term exposure to traffic-related air pollution and early death due to cardiovascular diseases and lung cancer, asthma onset in children and adults, and acute lower-respiratory-tract infections in children.

WHO data show that almost all of the global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants, with low- and middle-income countries suffering from the highest exposures.

State of Global Air (SoGA) 2024

It is an annual tracker of health impact of air pollution.
Prepared by – It is a collaborative assessment by the
- US-based Health Effects Institute (HEI)
- Institute for Health Metrics and Evaluation’s Global Burden of Disease (GBD) project.
This has been produced for the first time in partnership with UNICEF.
Data source – These results are linked to the Global Burden of Disease (GBD) 2021 report which estimated about 200 countries.
Assessment – It usually assess the impact of Particulate Matter (PM2.5) and Ozone on human health.
This 2024 report also covers the impact of nitrogen oxides (NO2).

What are the key findings of the report?

SoGR

During the pre-pandemic phase (1990 to 2019) – The order of the leading global causes of death were ischemic heart disease, stroke, chronic obstructive pulmonary disorder (COPD), and lower respiratory disease.
Post pandemic in 2021 – Covid-19 changed the order with age-standardised mortality from COVID ranking second after ischemic heart disease, and stroke and COPD dropping to third and fourth place, respectively.
Impacts of air pollution on human – It become the second largest killer globally after blood pressure, recording a dubious tally of 8.1 million deaths in 2021.

DeathsofAirPollution

Impact on children under five years - With more than 700,000 deaths, air pollution become the second leading risk factor after malnutrition globally.
As many as 500,000 of these child deaths are linked to household air pollution from cooking indoors using dirty fuels in Africa and Asia.
Polluted air is a big trigger for pneumonia and other respiratory infections and allergic diseases in children.

AirpollutionU5C

Impact of Climate Change – It can exacerbate the health burden of non-communicable diseases, including heart and lung diseases, during heatwaves.

What is the status of pollutants causing air pollution?

Even though PM2.5 (both ambient and household together) account for more than 90% of the total air pollution disease burden, NO2 and ozone are the growing risk factors globally.

Status of NO2 in Air pollution

Higher exposure to NO2 shows the growing risk from traffic exhaust in densely populated urban areas.
Seven of the 10 countries with the highest NO2 exposures are in the high income countries in West Asia.
The highest exposures to NO2 have been noted in countries with high socio-development index, including Singapore, Japan and Canada.
Impact on children – NO2 is a leading risk factor for the development of childhood asthma.
About 55% of 194 countries studied do not yet meet the annual WHO Air Quality Guidelines of 10 µg/m3, resulting in 42% of the world’s population being exposed to unacceptable levels.
Impact of climate – It is a catalyst for formation of ozone, yet another very harmful gas.
NO2 reacts with other chemicals in the atmosphere to produce both particulate matter and ozone.

Status of Ozone in Air pollution

Ozone levels have also increased in South Asia.
Impact of Climate change – The chemical reactions that form ozone increase when the air is warmer, especially during heatwaves.
Evidence shows that ozone spikes during heatwaves in China and Europe.
Exposure – The proportion of population experiencing high ozone exposures is also increasing in India, Nigeria, Pakistan, and Brazil.
Impact on vegetation – It can reduce crop yields, damage biodiversity, and undermine food security and nutrition.
Impact on humans – In 2021, ozone was responsible for 56% of all global ozone deaths reported in South Asia.
Exposure to ozone is associated with an increased risk of both acute and chronic respiratory illnesses.
India – It has recorded about 237,000 ozone related deaths.
In 2021, nearly 50% of all ozone-related COPD deaths were in India, followed by China and Bangladesh.

Status of PM 2.5 in Air pollution

Evidently, nearly 20% of the global ambient PM2.5 is attributed to household air pollution.
Impact on humans – India and China have recorded 2.1 million and 2.3 million deaths respectively and together account for nearly 55% the total global disease burden from particulate matter.

What lies ahead?

Emulate the successful policy decisions – There has been a 61% reduction in the age-standardised death rate from household air pollution.
This improvement has been possible due to growing access to clean energy for cooking, grid electricity, cleaner-burning cookstoves, and cleaner fuels.
Tackle air pollution – It can be done by reducing toxic emissions and greenhouse gases, which will improve public health and combat climate change.

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