How PM2.5 in haze affects the human body

SINGAPORE – The haze in Singapore caused by Indonesian forest fires contains PM2.5 micro-pollutants 30 times smaller than the width of a strand of hair.

These particles are invisible to the naked eye and can get lodged deep in our lungs and enter the bloodstream.

Here are the different ways your body can be harmed when this happens.

Respiratory system

PM2.5 pollutants are so small they evade the human body’s natural defence filters found in the nose and upper airway, and penetrate deep into the smallest air sacs of the lungs (alveoli).

This causes structural, inflammatory, and functional damage to the respiratory system.

Symptoms include chronic cough or persistent hacking that lasts for weeks or months, shortness of breath, and coughing up blood or blood-streaked mucus from damaged vessels.

Brain

PM2.5 harms the brain after entering it via the bloodstream and nasal nerve endings, triggering brain inflammation, injuring brain cells, and causing oxidative stress and damage to the blood-brain barrier. Symptoms include cognitive decline, memory loss, brain fog, and fatigue.

Ingested or inhaled particles also disrupt gut bacteria, causing inflammation and other gut issues. This, in turn, sends inflammatory signals to the brain, contributing to conditions such as anxiety and brain fog.

Heart

The tiny airborne particles affect the heart by penetrating deep into the lungs, entering the bloodstream, and triggering systemic damage. This can result in heart attacks (myocardial infarction), stroke, heart failure, high blood pressure (hypertension), and dangerous heart rhythms (arrhythmias).

PM2.5 can also cause blood platelets to be stickier and more prone to forming clots, which can block blood flow to the heart or brain. When this happens in the heart, it can lead to a heart attack (myocardial infarction); in the brain, it can cause an ischaemic stroke.

PM2.5 also irritates nerve receptors in the lungs, messing with the nervous system signals that control heart rate and heart rhythm.

Short-term or acute spikes in PM2.5 can trigger plaque ruptures and sudden cardiac events, including heart attacks and heart failure.

Long-term exposure to PM2.5 speeds up the build-up of fatty plaques inside the arteries, narrowing blood vessels and raising blood pressure.

Skin

PM2.5 dust particles can settle on the skin, collect in pores or texture irregularities, and alter critical barrier lipids, such as ceramides. This leads to dryness, dehydration, and heightened skin sensitivity.

The particles can activate receptors and inflammatory pathways, releasing immune system reactions and causing facial redness (erythema) and irritation.

Eyes

PM2.5 sticks to eyelids, conjunctiva, or cornea, exacerbating inflammation, damaging the tear film and conjunctival surface, leading to various eye conditions, including dry eyes, burning sensation, foreign body sensation in the eyes, redness, conjunctivitis, itching, excessive tearing, and impaired vision.

The inflammation can spread to the eyelids, causing redness, heavy secretions, and plugged gland ducts.

Those with contact lenses experience faster tear breakdown and increased discomfort during poor air quality days.