Smog starts slowly.

At first you can’t see it, but you can smell it. It smells like something is burning. And it becomes more intense as the temperature drops.

Then the smoke and fog begin to envelop you and the city around you. Now you can see it. You walk through the smoke and there is a thick ceiling above your head.

If you don’t wear a mask or lower it for a moment, you will immediately inhale the bitter air.

Your throat may become itchy and painful. As it gets worse, you start sneezing and coughing. But for others it is even worse: children, the elderly, people with breathing difficulties. The hospitals know to expect the influx.

Lahore and its 13 million inhabitants have been suffocating for a week now; the air quality index has repeatedly passed the 1,000 mark this month – anything above 300 is considered dangerous.

Pakistani officials have scrambled to respond to the crisis; its scale is unprecedented, even in a city that experiences smog every year at this time.

Schools have been closed, workers have been told to stay home and people are being urged to stay indoors – part of a so-called ‘green lockdown’, which has also seen motor rickshaws, heavy vehicles and motorcycle parks banned in hotspot areas.

By the end of the week, the Lahore High Court had ordered all markets in Punjab province to close at 8pm every evening, with complete closure on Sundays. Parks and zoos are also closed until November 17.

The problem, according to NASA scientist Pawan Gupta, is that pollution levels in the city “usually peak in late November and December.”

“So this is just getting started. The days of the worst pollution are probably still ahead of us,” he warned.

The smoke that has enveloped Lahore, in Pakistan’s Punjab province, can be seen from space – as can part of the cause.

Satellite images from the American space agency NASA show both the thick layer of smog and the multiple fire concentrations in the region between the Indian capital Delhi and Pakistan’s Lahore.

The same image, six weeks earlier, shows clear skies and – crucially – far fewer fires.

A major cause of the smog is the fires caused by post-harvest stubble burning by farmers in both Pakistan and India – a quick way to prepare their fields for the next crops.

This year, NASA estimates there will be “between 15,500 and 18,500 fires,” more than in most years, according to Hiren Jethva, senior research scientist at NASA’s Goddard Space Flight Center and Morgan State University.

According to Pakistan’s environmental protection authorities, about 30% of the smog in Lahore comes from across the border with India. The Indian government this year doubled fines for farmers caught burning stubble in a bid to tackle the problem.

But much of Lahore’s air pollution comes from its five million motorcycles and the exhausts of millions of other vehicles. According to the Associated Press of Pakistan, the Lahore High Court on Friday identified emissions from heavy traffic as the main cause of the smog.

Then there are the industries on the outskirts of the city – such as coal-fired brick kilns – which cause even more pollution to the air.

And in the final months of the year, this all combines with cold air flowing down from Tibet, creating the smog that currently hangs over the city.

It is clear that the toxic air is making people sick.

According to the U.S. Environmental Protection Agency’s (EPA) Air Quality Index (AQI), a reading of 50 or lower indicates good air quality, while a reading above 300 indicates hazardous air quality.

According to WHO guidelines, the average concentration of PM2.5 should be below five.

Abid Omar, founder of the Pakistan Air Quality Initiative, which collects data from 143 air quality monitors across the country, said readings in Lahore “exceeded the index every day in November.”

“Some locations in Lahore have crossed 1,000,” he said, adding, “On Thursday we had a reading of 1,917 on the AQI scale.”

On Tuesday, it was widely reported that 900 people had been hospitalized in Lahore with breathing difficulties.

“More and more people are coming with asthma complaints, itchy throat and coughing,” says Dr. Irfan Malik, a pulmonologist at one of the largest hospitals in Lahore.

He has already seen an increase in the number of patients complaining of respiratory illnesses – “particularly worrying as we have not yet seen our first cold snap of the winter season”.

Danger is a constant concern for Lahore resident Sadia Kashif.

“Like every mother, I want to see my children running and playing without fear of pollution,” she told the BBC.

“I see my children struggling with coughs and breathing problems these days, and it is a painful reminder that our air has become extremely toxic.”

But the current ‘green lockdown’ has left her unimpressed.

“It is easy for the government to close schools instead of taking real steps to tackle the crisis,” Kashif said.

For years, authorities have struggled to find a solution to Lahore’s pollution problem.

The government hopes short-term solutions will provide a reprieve, but says long-term solutions – such as improving public transport – will take time.

Meanwhile, Punjab Chief Minister Maryam Nawaz announced this week that she plans to write a letter to her counterpart in India’s Punjab inviting them to engage in “climate diplomacy” as it impacts both regions . Delhi says it has not heard from Pakistan on the issue.

However, Omar points out that air pollution is not a seasonal problem, but a persistent problem.

“Lahore is much more polluted than Delhi, with pollution episodes lasting longer and reaching higher peaks,” he notes.

And it’s getting worse, he believes. According to his own analysis of the data, pollution levels increased by 25% in October compared to the same period last year.

Governments on both sides of the border must act quickly to tackle this problem, he argues.

“The roadmap to clean air is clear, but current policies by both India and Pakistan are not enough to significantly reduce pollution.”

It has made him skeptical about change in the near future.

“I tell people: blue skies are an indicator of good governance,” says Omar.