DELHI — Hundreds of people staged a rare protest in Delhi on Sunday against worsening air pollution, as air quality continues to deteriorate in India's capital and nearby regions.

Over the past three weeks, Delhi's Air Quality Index (AQI), which measures the level of PM 2.5 or fine particulate matter in the air that can clog lungs, has hovered between 300 and 400, which is 20 to 30 times higher than the World Health Organization's safe limit.

The protesters held banners and shouted slogans, demanding that the government take action to curb pollution.

Around 80 of them were briefly detained near India Gate after police said they did not have permission to gather at the landmark.

"Our lungs are getting damaged. The government should declare it a health emergency until they find a solution to it," a protester told news agency PTI.

Air quality in Delhi and its suburbs is relatively poor throughout the year due to vehicular emissions, dust and industrial pollutants. But the problem gets worse in the winters because of farmers burning crop stubble in neighbouring states, along with low wind speed trapping pollutants close to the ground.

Though air pollution is a recurring problem in northern India, this was the first big protest on the issue in a while.

On Monday morning, Delhi's AQI was 330 according to the federal government-run Safar app.

Levels between 101 and 200 are considered moderate, while those between 201 and 300 are "poor". Between 301 and 400 is categorised as "very poor" and a figure higher than 400 is considered "severe".

But the readings were higher on other sources, such as private air quality monitors

According to the Air Visual app operated by Swiss air quality technology company IQAir, Delhi's pollution levels were between 414 and 507, which the app classified as hazardous.

On Sunday, close to 400 men and women of all ages, including children accompanying their parents, participated in the protest at India Gate.

Several demonstrators wore gas masks as a symbolic gesture of protest.

A banner read 'Right to live, not just survive', while another said 'Life in Delhi: Take birth, breathe, die'.

Police said they detained around 80 people who were released later.

"India Gate is not a protest site. It is a high-security area," senior Delhi Police officer Devesh Mahla told reporters, adding that all the detained individuals were adults.

Several opposition leaders, university students, journalists and environmental activists were among the protesters.

"We have reached severe and hazardous levels of pollution, but the GRAP measures have not been implemented," Delhi-based environmental activist Bhavreen Kandhari told PTI.

GRAP refers to the government's Graded Response Action Plan (GRAP) to tackle air pollution in Delhi and its suburbs.

Currently, the second level of the action plan is in place. It imposes restrictions on the use of diesel generators and burning of coal and firewood.

The third level of the action plan, GRAP III, which would also ban all non-essential construction activities and the plying of diesel vehicles in Delhi, is yet to be imposed despite air quality levels getting worse.

"This is about our children… My children will live 10 years less than their cousins (in other cities) who breathe cleaner air. We still have hope, and that's why we are here," Ms Kandhari added.

Another protester told reporters that recent measures taken by the government, such as sprinkling water on the roads and a recent unsuccessful cloud-seeding attempt, are not solving the problem. "The government should take the issue seriously," he said.

Delhi's environment minister Manjinder Singh Sirsa, however, said on Sunday night that the government was taking all possible steps to address the issue.

"We have installed anti-smog guns in all high-rise buildings, dust mitigation is being done across the city through water sprinklers, all construction sites are being monitored, and we have increased electric vehicles in Delhi's fleet of public buses," he said in a video statement. — BBC