The Delhi Pollution Control Committee (DPCC), which collected samples from 18 locations across the city, said PM 2.5 and PM 10, respirable particulate matters that cause harm to the respiratory system, saw an average reduction of 50 and 30 per cent respectively.

“PM 2.5 air pollution levels on Saturday at these 18 locations showed recordings of less than 100 micrograms per cubic metre (ug/m3) at nine locations, which is more than 50 per cent less than average recordings since the odd-even regulations were put in place for four-wheeled vehicles since January 1,” an official statement said.

Experts had put yesterday’s air quality in the ‘moderate’ category, which is a rarity during the city’s winters, notorious for soaring levels of pollutants.

Persistently high levels of PM 2.5 and PM 10 and smog largely owing to hostile weather conditions over the past one week had put questions marks over the efficacy of the odd-even scheme.

The safe limits of PM 2.5 and PM 10, a product of vehicular emissions and dust among others, are 60 and 100 each. Anything beyond that is harmful as the particles get embedded deep into the lungs and, subsequently, enter the bloodstream.

Of these total 18 locations, the lowest measurement was at 59 (Jhilmil Colony, Shahdara) and the highest at 301 (Kazipur, Najafgarh).

DPCC’s mobile vans have so far collected samples from around 150 locations.

In 18 locations measured on Saturday, even the PM 10 air pollution levels have shown a “marked decline”, the government said adding that it have been recorded between 135-475.

“Scientists have been consistently predicting that the moment weather conditions improve, the results of odd/even formula for four-wheeled vehicles will show immediate results,” the statement said.