Why is the pollution season in Hanoi unusually longer than every year?

Normally, the air pollution season in Hanoi lasts from October to March of the following year. However, this year 2025, PM2.5 fine dust still “quietly stays” until April, causing the air quality to continuously be at the level of poor – bad – very bad. This seriously affects public health, especially children, the elderly, and people with underlying respiratory diseases.

1. Why is the pollution season in Hanoi unusually longer than every year?

1.1. Overloaded emission sources

– Heavy traffic, especially in the inner city with high vehicle density, often causes congestion – emitting large amounts of NOx, CO and PM2.5 ultra-fine dust.

– Non-stop urban construction: Excavation, demolition, leveling, material transportation… create large amounts of dust, especially when there are no careful covering measures.

– Spontaneous burning of straw and waste: Still common in suburban and suburban areas, especially after each harvest season.

– Industrial activities mixed in residential areas: Many small production facilities do not have a standard exhaust gas treatment system.

All of the above factors create a “cloud of pollution” that cannot escape without favorable weather conditions, causing air pollution to increase and become difficult to control.

1.2. Adverse weather

In the first months of this year, especially in April 2025, there was little rain, high humidity, and weak winds – these conditions limit the diffusion of fine dust and polluted gases, causing them to be “stuck” close to the ground, where people breathe.

– Temperature inversion (higher air temperature is lower than lower air temperature): This phenomenon prevents air from convection, and pollutants are “trapped” in the air layer near the ground.

– Climate change: Unstable weather, unseasonal rain or prolonged heat disrupt the natural purification cycle of the atmosphere.

As a result, the air is not cleaned properly as every year, causing fine dust to persist longer and the AQI index to remain high, seriously affecting health.

2. Harmful effects of air pollution on health

Dirty air does not only cause temporary discomfort. Fine dust particles, toxic gases, bacteria and volatile organic compounds (VOCs) when entering the body can lead to a series of health problems, from acute to chronic – especially serious for people with weak resistance.

2.1. Fine dust PM2.5 – “silent killer”

Ultra-small in size (≤ 2.5 micrometers), fine dust easily penetrates the body’s natural protective layers, goes deep into the lungs, and even into the blood.

– Causes chronic bronchitis, asthma, pneumonia, and even lung cancer.

– Increases the risk of cardiovascular disease, many studies show that PM2.5 is related to high blood pressure, stroke, and myocardial infarction.

– Especially dangerous for young children, the elderly, pregnant women, and inpatients.

2.2. Bacteria, viruses – pathogens in the air

In polluted environments, bacteria and viruses can easily spread and cross-infect, especially in hospitals, schools and closed spaces. This increases the risk of acute respiratory infections, influenza, and even widespread epidemics if there are no strict air control measures.

2.3. VOCs & toxic gases – slow attack

Formaldehyde, benzene, toluene… are volatile compounds emitted from furniture, detergents, wall paint… Causing symptoms such as headaches, dizziness, nausea, skin – eye – throat irritation, neurological effects and can cause cancer if exposed for a long time.

2.4. Weakened immune system – slow recovery

In polluted environments, patients after surgery or undergoing treatment often have a prolonged recovery time due to the immune system being continuously attacked. In young children and the elderly, air pollution increases the risk of acute respiratory failure and pneumonia, causing a heavy burden on the health system.

2.5. Cost Burden and Quality of Life

Air pollution increases the number of hospital stays, treatment costs, and premature deaths each year. It reduces quality of life, labor productivity, and disrupts daily activities and learning.

3. Puritrak’s air purification solutions

In the context of increasingly unpredictable and longer-lasting air pollution, proactive solutions to filter the air in every living, working and treatment space are mandatory. Puritrak provides modern air filtration systems, applied to:

• Hospitals – ICU rooms – Operating rooms – Hospital rooms
• Schools – Classrooms – Medical rooms – Libraries
• Offices – Houses – Hotels – High-rise apartments

Advantages of Puritrak air filtration systems:
– Filter fine dust PM2.5, PM1.0, deodorize VOCs, kill bacteria in the air

– Integrated real-time air quality monitoring sensor

– Quiet operation – energy saving – easy maintenance

– Flexible design suitable for each type of space

Here is the answer to the question “Why is the pollution season in Hanoi longer than usual?” If you are considering an air purification solution for your unit, please contact Puritrak immediately for free consultation from our team of experts.

Puritrak products and services:

• Puritrak air purifier
• Puritrak indoor air quality measuring device
• Puritrak outdoor air quality measuring device
• AQM solution

Contact info:

• Hotline: 0904.800.006
• Website: puritrak.com
• Email: [email protected]
• Fanpage: Puritrak