More than a decade ago, engineer Abid Omar had a "sneaking suspicion" that what the government described as seasonal fog was actually a new phenomenon.

"It wasn't there in my childhood" in Lahore, said the 45-year-old who now lives in coastal Karachi, where the sea breeze no longer saves residents from smog.

With no official data available at the time, Omar asked himself: "If the government is not fulfilling its mandate to monitor air pollution, why don't I do that for myself?"

His association, the Pakistan Air Quality Initiative (PAQI), installed its first monitor in 2016 and now has around 150 nationwide.

The data feeds into the monitoring organisation IQAir, which in 2024 classified Pakistan as the third most-polluted country in the world.

Levels of cancer-causing PM2.5 microparticles were on average 14 times the World Health Organization's recommended daily maximum.

Schools are often shut for millions of children and hospitals fill up when the smog is at its worst, caused by a dangerous combination of poor-quality diesel, agricultural burning and winter weather.

PAQI data has already played a key role in the adoption of pollution policies, serving as evidence during a 2017 case at Lahore's high court to have smog recognised as air pollution that is a danger to public health.

Using one of their air monitors, PAQI demonstrated that "the air quality was hazardous inside the courtroom", Omar said.

The court then ordered the regional government of Punjab to deploy its own monitoring stations -- now 44 across the province -- and make the data public.

But the government also says private monitors are unreliable and cause panic.

Researchers say, however, that these devices are essential to supplement official data that they view as fragmented and insufficiently independent.

"They got alarmed and shut down some stations when the air pollution went up," Omar said.

- 3D-printed monitors -

Officials have overhauled the management of brick kilns, a major source of black carbon emissions, and taken other measures such as fining drivers of high-emission vehicles and incentivising farmers to stop agricultural burning.

Worried about their community in Islamabad, academics Umair Shahid and Taha Ali established the Curious Friends of Clean Air organisation.

In three years, they have deployed a dozen plug-sized devices, made with a 3D printer at a cost of around $50 each, which clock air quality every three minutes.

Although they do not contribute to IQAir's open-source map or have government certification, their readings have highlighted alarming trends and raised awareness among their neighbours.

An outdoor yoga exercise group began scheduling their practice "at times where the air quality is slightly better in the day", said Shahid.

He has changed the times of family outings to minimise the exposure of his children, who are particularly vulnerable, to the morning and evening pollution peaks.

Their data has also been used to convince neighbours to buy air purifiers -- which are prohibitively expensive for most Pakistanis -- or to use masks that are rarely worn in the country.

- 'Right to breathe' -

The records show air quality remains poor throughout the year, even when the pollution haze is not visible to the naked eye.

"The government is trying to control the symptoms, but not the origin," said Ali.

Pollution exposure in Pakistan caused 230,000 premature deaths and illnesses in 2019, with health costs equivalent to nine percent of GDP, according to the World Bank.

Frustrated with what they see as government inaction, some citizens have taken the legal route.

Climate campaigner Hania Imran, 22, sued the state in December 2024 for the "right to breathe clean air".

She is pushing the authorities to switch to cleaner fuel supplies, but no date has been set for a verdict and the outcome remains unclear.

"We need accessible public transport... we need to go towards sustainable development," said Imran, who moved from Lahore to Islamabad in search of better air quality.

Pollution has multiple causes, she said, and "it's actually our fault. We have to take accountability for it."