Artificial rain was used in an attempt to reduce pollution levels in Lahore, Pakistan.
The capital of the eastern province of Punjab, near the Indian border, has some of the worst air quality in the world and has become extremely polluted due to a growing population of more than 13 million people.
By early December, the air quality in the city grew so bad that schools, markets and parks were closed for four days. By last weekend, the city’s air quality index (AQI) had reached levels considered extremely hazardous to health.
To try and reduce this, the Punjab government on Saturday used cloud seeding to create rain at 10 locations around the city using a small Cessna plane.
To create the clouds, there must be enough moisture already present in the clouds in the lower atmosphere. In the summer, common table salt mixed with water is sprayed from airplanes over the cloud patches. After a few hours, the fog integrates with the clouds and produces rain. In winter, the clouds are seeded using silver iodide flakes, which can be fired from a vehicle or an aircraft.
The practice, also known as “blueskying”, has been used to cause precipitation in several countries in the Middle East, as well as China and India.
Bilal Afzal, the provincial caretaker minister for the environment, said the cloud seeding was a success but admitted rainfall was “poor” as the cloud quality was not very good. Nevertheless, Lahore’s air quality improved with just a few millimeters of rain, dropping from an AQI of more than 300 to 189, Afzal said. However, the benefits only lasted a few days before pollution returned to its previous level.
The exercise did not cause any significant disruption. “I just got a splatter on my car while driving home from the clinic around 3pm and thought it was bird droppings,” says Zaeema Naeem, a doctor in Lahore.
Afzal said the authorities plan to carry out cloud seeding regularly during the smog season. “If we can clean our air at the cost of fuel for one small plane, the exercise will be worth it,” he said. However, this would mean buying or renting a small plane. As for the emissions from that, he said it would only be equal to the equivalent of two or three cars running for about four hours.
However, climate experts have warned that the effects of cloud seeding can be unpredictable. Malik Amin Aslam, a former environment minister, said that it could be difficult to stop it once it has caused rain. “The stopping of that downpour is determined by nature,” he said.
Dr Ghulam Rasul warned that “overdose can lead to hailstorm or torrential rain”. The head of the climate change program at the International Union for Conservation of Nature, and a former director-general of the Pakistan Meteorological Department, said that while this could provide temporary relief from smog, it was not a sustainable solution and could cause severe drought . conditions, potentially making fog and smog even more persistent.
Aslam agreed that the government should “study the consequences of tampering with nature and use this tool very sparingly; it’s like using steroids as a last ditch effort to break the cycle of unlivable smog”. Such solutions, he added, could take the focus away from addressing the “real sources of smog, such as transport, industrial emissions, crop and waste burning and disappearing green cover”.
He said the transport industry is responsible for 50% of the emissions in Lahore, adding that the government is trying its best to tackle it.
Fehmeda Khan, a local doctor, has observed a threefold increase in patients complaining of respiratory diseases and allergies due to dust. She advised residents: “Close your windows to avoid dirty outdoor air, avoid going out and wear a mask if you do; and do nasal saline rinses morning and night as a daily regimen.”