SMOG pollution


source of pollution and impact on health and environment

Have you ever noticed a thick air, laden with a yellowish haze that limits visibility in the city? It’s not fog, but rather a form of air pollution: smog. It represents a major environmental challenge, impacting our health and ecosystems.

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What is SMOG?
How is SMOG formed?
The difference between fog and SMOG
SMOG’s effects on health and the environment
How to reduce SMOG? 

What is SMOG?

The term “SMOG” is derived from “smoke” and “fog.” It describes the presence of a thick fog laden with suspended harmful particles in the air, making the atmosphere hazy and potentially dangerous for human health and the ecosystem.

How is smog formed?

SMOG primarily forms from a complex combination of atmospheric pollutants originating from various sources, notably human activities, industrial emissions, vehicular traffic with vehicle exhaust fumes, chemicals, and atmospheric reactions.

There are two main types of SMOG:

👉 Photochemical SMOG: :

This type of SMOG forms when emissions of pollutants from vehicles, factories, and other sources react under the influence of sunlight.

Nitrogen oxides (NOx) and volatile organic compounds (VOCs) are key precursors of this type of SMOG. In the presence of sunlight, these chemical compounds react to form atmospheric pollutants, such as tropospheric ozone, peroxyacetyl nitrate (PAN), and other harmful compounds detrimental to human health and the environment.

It’s also known as ‘summer smog‘ as it forms when temperatures are higher and sunlight is abundant.

👉 Sulfurous SMOG: :

This type of SMOG is more common in regions where the combustion of coal or other fossil fuels is used intensively.

It mainly consists of fine particles, sulfur dioxide (SO2), and smoke, forming a dense and toxic fog.

It can be termed ‘winter smog’ due to the extensive use of wood burning. Winter conditions, with a more stable atmosphere and colder temperatures, can lead to the accumulation of fine particles and sulfur dioxide (SO2) near the ground, forming this type of SMOG.

How to recognize them? Smog can have different colors that provide information about the involved atmospheric pollutants.

SMOG Color

* it’s important to note that the specific color of smog can be the result of a complex combination of different pollutants present in the outdoor air and local meteorological conditions.

Difference between Fog and SMOG

SMOG and fog are two distinct atmospheric phenomena, although they may sometimes appear similar.


SMOG composition

SMOG is a polluted haze formed, as previously mentioned, by the reaction of exhaust gases and chemicals in the air, often due to human activity, whereas fog is condensed water vapor in the air, occurring when atmospheric humidity is high and temperatures drop. The main difference lies in their composition: SMOG contains pollutants, whereas fog is primarily condensed water.

It is easily distinguished from fog as it is dense, very thick, brown, gray, or yellowish. Additionally, SMOG can have a pungent or irritating smell due to chemical pollutants, while fog generally does not have a specific odor. 

💡 Good to know: SMOG is typically associated with dense urban areas and pollution, whereas fog can form in various environments, both urban and rural, depending on weather conditions.

SMOG : effect on health and environment 

Impacts of SMOG on health:

SMOG, a form of outdoor air pollution, poses a serious threat to respiratory health. It is directly linked to conditions affecting the lungs. This polluted air is associated with respiratory problems and diseases such as asthma, pulmonary and cardiovascular diseases, as well as an increased risk of cancer. It is irritating to the nose, eyes, and throat, particularly when it occurs in spring during pollen season. This mixture of air pollutants represents a health hazard. Children, pregnant women, and the elderly are most exposed to smog, with its effects similar to those of cigarette smoke..

💡 Good to know:In December 1952, London was engulfed in a thick SMOG for 4 days. According to a report from the journal Environmental Health Perspectives published in 2004, nearly 12,000 people are estimated to have lost their lives due to that episode of air pollution.

Impacts of SMOG on the environment:

In addition to affecting air quality, SMOG can damage vegetation by altering their ability to carry out photosynthesis and disrupt terrestrial and aquatic ecosystems due to the acidic deposits often present in smog.

How to reduce SMOG ?

According to the World Health Organization, ambient air pollution, particularly SMOG, is one of the greatest environmental health risks. Collective efforts from governments, businesses, and individuals are crucial to mitigate this issue.

Implementing environmental monitoring tools is a crucial step in this process. At Meersens, we offer more than just a simple solution; we provide a comprehensive and in-depth view of the situation through real-time and predictive multi-pollutant monitoring covering air quality, pollen, noise, water, weather, and forest fires – to prevent, monitor, and control pollution.

These data are easily accessible and readable on our Environmental Intelligence Platform. They offer the ability to compare results to national, international standards, or your own air quality thresholds. This thorough analysis allows you to make informed decisions to improve public health.


To learn more about our innovative environmental solution and discover how we can contribute to the health of your community, contact us today.

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