How Bad Is ‘Bad’ Air? Here’s What Different Air Quality Index Levels Mean For Your Health

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When haze settles over Malaysian skies, one measurement suddenly becomes very important: the Air Pollutant Index (API).

You might see readings of 40, 80 or 150 being shared online, but what do those numbers actually mean for your health?

Malaysia uses the Air Pollutant Index (API) to communicate air quality and its potential effects on human health, with readings ranging from good to hazardous.

While the exact pollutants contributing to a reading can vary, the basic rule is simple: the higher the number, the greater the potential health risk.

Here’s a simple breakdown.

0–50: Good

At the lower end of the scale, the air is considered good, with little reason for most people to worry.

For most people, including children and those who exercise outdoors, this is essentially business as usual. You can go for a jog, walk the dog, cycle or spend time outside without needing to make special changes because of air pollution.

Think of this as green-light territory.

51–100: Moderate

Once the reading enters this range, air quality is still generally acceptable, but pollution is becoming more noticeable.

Most people can continue their normal outdoor activities. However, people who are particularly sensitive to air pollution may start experiencing minor effects.

Under the commonly used AQI health scale, 51–100 is considered “Moderate”.

So if you’re healthy and the reading is, say, 70, there’s generally no reason to panic. But it is a good reminder to keep an eye on the number if the pollution is worsening.

101–150: Unhealthy For Sensitive Groups

This is where things start getting more serious.

At this level, people who are more vulnerable to air pollution may begin experiencing health effects. This can include people with respiratory or heart conditions, children and older adults.

Symptoms can include coughing, throat irritation, breathing difficulties or worsening of existing respiratory problems.

For everyone else, the risk is lower, but that doesn’t mean the air is completely harmless. The EPA’s guidance notes that health effects become a concern above 100, initially for sensitive groups and increasingly for everyone as the number rises.

If you’re sensitive to pollution, this is the point where you should start cutting down on prolonged or strenuous outdoor activity.

151–200: Unhealthy

Now we’re in the red zone.

At this level, pollution can affect everyone, not just people considered vulnerable.

You may notice the symptoms mentioned earlier, along with more severe ones such as headaches, chest discomfort or difficulty breathing, particularly if you spend a lot of time outdoors or exercise.

Sensitive groups can experience more serious effects.

The EPA classifies 151–200 as “Unhealthy”, while recommending greater exposure reduction as air quality deteriorates.

That outdoor run you’ve been planning? Maybe skip it.

201–300: Very Unhealthy

At this point, we’re no longer talking about simply having an unpleasant haze.

An API/AQI reading in this territory represents a serious health concern for the wider population.

The equivalent AQI category, “Very Unhealthy”, means widespread health effects can be expected among the general population, with potentially more serious effects among sensitive groups.

Outdoor exercise should be avoided or heavily restricted, and people should spend as little time as possible breathing polluted outdoor air.

If you absolutely have to go outside, keeping the trip short and avoiding strenuous activity becomes particularly important.

301–500: Hazardous

This is the danger zone.

A reading above 300 is classified as Hazardous on the standard AQI scale, meaning the entire population is more likely to be affected.

At this point, outdoor physical activity should be avoided.

Even healthy people can experience significant symptoms when exposed to extremely polluted air, while people with existing health vulnerabilities face an even greater risk.

In other words, this isn’t a “wear a mask and carry on” situation. If air quality reaches this level, staying indoors and reducing exposure should be the priority.

Sarawak enters “emergency” levels of API

This is the current situation in Serian, Sarawak, where API levels have reached a dangerous 518 as of 10am on Friday (4 September), as reported by The Star.

Apart from Serian, Kuching’s API reading of 310 has also been categorised as hazardous, followed closely by Samarahan (281) and Sri Aman (245), which showed very unhealthy levels.

The death of Sampurna

Meanwhile, the Sarawak Tribune reported on Thursday (3 September) that an Orangutan named Sampurna, which was rescued after being found struggling to breathe amid thick haze, had died.

Sampurna was discovered by villagers in Indonesia’s East Kalimantan, near a community-owned palm oil plantation.

The primate was found lying in a drainage ditch after it had collapsed from breathing difficulties.

Rescuers from the West Kalimantan Natural Resources Conservation Agency (BKSD) confirmed that Sampurna died on 30 August, after being given days of emergency treatment at the Foundation for International Animal Rescue Indonesia’s rehabilitation centre.

It was reported that the necropsy, indicating prolonged exposure to smoke, likely contributed to his death.

According to various news reports, the haze has drastically impacted wildlife in Borneo, posing a significant threat to Bornean Orangutans while the destruction of vast swathes of vegetation has created an immediate famine for local wildlife.

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