Air pollution in large parts of northern India, including the capital New Delhi and neighboring Pakistan, continued to hover in "hazardous" territory on Sunday, leaving many residents complaining of breathlessness and chest pains.

Hospitals in the region saw a huge spike in patients suffering from respiratory problems.

Doctors at the government-run Vallabhbhai Patel Chest Institute in New Delhi said patient numbers had more than tripled since pollution levels spiked earlier in the week.

"Beginning this week, we are seeing between 250-300 patients, more than three times the usual," emergency ward doctor Mansi Verma told the Agence France-Presse news agency.

In Pakistan's eastern city of Lahore, hospitals were overwhelmed with patients complaining of throat and eye irritation. Provincial health minister Salman Rafiq said the hospitals in the city were filled to capacity.

Pollution levels across large swathes of northern India and Pakistan worsened earlier in the week when a thick blanket of poisonous air particles enveloped the region, mainly due to the burning of crop stubble by farmers in the Indian states of Punjab and Haryana.

'Hazardous situation'

India's capital New Delhi, which borders Haryana, was worst hit, where the problem has been compounded by dust from construction sites, vehicle emissions and burning of coal and garbage. 

The poor air quality has prompted a temporary shutdown of the education system, with doctors declaring it a "public health emergency."

The levels of fine particulate matter (PM2.5) — small particles that pose the greatest threat to lungs — in some places in the city hovered well over double the threshold of 300 that is classed as "hazardous."

The World Health Organization's guidelines say 25 is the maximum level of PM2.5 anyone can safely be exposed to over a 24-hour period.

"The situation is grim. I am having difficulties breathing. But it's a lot worse for my two-year-old daughter," journalist Vikas Pal Singh told DW.

"My wife and I are keeping our daughter indoors as much as possible and ensure she wears a mask before we step out."

Systematic reforms needed

Delhi authorities have responded with urgent measures including a temporary ban on construction activity, entry of commercial trucks into the Delhi region and use of diesel generators. Parking charges have been raised to dissuade residents from using cars.

But these measures have led to only a 20 percent drop from the pollution levels seen earlier in the week, Anumita Roychowdhury of New Delhi's Centre for Science and Environment told DW.

"We need systematic reforms for a sustained good air quality. There is a need to improve public transport and ban the use of dirty industry fuel," Roychowdhury said. "Otherwise, the scope and impact of the emergency measures will be limited."

The WHO in May, 2014 found Delhi to be the most polluted city in the world. The Indian capital and 12 other Indian cities made it to the top 20 in the ignominious list of world's worst polluters.

Underscoring the problem, a study by the Lancet medical journal last month found that pollution claimed as many as 2.5 million lives in India in 2015, the highest in the world.

Respite in sight

Delhi residents can expect a respite in the coming days with the weathermen forecasting light rain that is expected to clear the smog.

There is also a forecast of showers across the border in Pakistan, where smog has led to suspension of traffic on several motorways due to poor visibility that caused several road accident deaths.