Scientists want more time to analyse ‘odd-even’ impact on Delhi’s air

NEW DELHI: Scientists under the ministry of earth sciences want to assess the impact of wind, temperature and humidity before sharing their analysis of the impact on air pollution in Delhi when car movement was restricted for 15 days, officials said.

The ministry was earlier scheduled to share the analysis of the impact of ‘odd-even’ rule on Monday.

Initial data shows that pollution was actually higher on most days during the experiment in which cars with odd and even numbers were allowed on alternate days. Air pollution was lower in the week before the restriction and fell sharply on the day when all cars were allowed on the road.

Scientists said they need to study the impact of the weather.

“To actually know how car emission was reduced we have to separate the impact of weather from the models,” said a meteorologist at India meteorological department ( IMD). “The detailed report may take 4-5 days as we have to analysis the data before January 1, after January 15, and between January 1 and 15. Our report is science and it will take time,” the person said.

Air quality of Delhi overall remained in poor category in the first 15 days of the year when the ‘odd-even’ rule was imposed, touching severe during January 4-7.

A senior scientist at Indian Institute of Tropical Meteorology said the winds in the first week of January was calm, ensuring that the particulate matter 2.5 (small particles) over Delhi touched a high of 289 microgram per cubic metre. “In the second week winds speed increased and hence on the last day of the odd-even car rule PM 2.5 came down to 113 microgram per cubic metre.”

The scientist said the variability of PM 2.5 between any given two days was very high from 57%to 150%. “Whether the pollution can be attributed to trucks, two wheelers or four wheeler or even dust we will analyse,” the person said.