The moment I submitted my dissertation at Cardiff University, I packed my stuff and took my flight for home – Lahore. After spending a year in the UK on a Chevening scholarship, I couldn’t be happier to return to meet my friends and family but there was something else, too, waiting for me at the Lahore airport — smog.The moment I stepped out of the plane, I choked, as polluted air laden with particulate matter and toxic fumes filled my lungs. I could even smell something burning in the air, something pungent. A dense layer of smog had engulfed the historic city.As I battled the unfamiliar atmosphere, another Chevening scholar from Cardiff University visited her hometown, some 400km from Lahore.Iknoor Kaur had returned to New Delhi on November 13 for a private affair. When Iknoor Kaur stepped out of the plane at New Delhi’s Indira Gandhi International Airport, she could smell something burning. “It was extremely pungent and really bad,” she says.Kaur had spent her whole life in India but she had never experienced anything as bad as this year’s smog. Due to the rising air pollution problem, her family had brought several air purifiers. She says, “If the doors and windows remain closed, the air purifier’s indicator turns green but if the door is opened for even 10 seconds, the indicator goes red. That’s how bad the air pollution problem in New Delhi is.”The air pollution problem knows no boundaries, and quite often leaders of both countries have blamed each other for causing smog on the other side of the border.In Pakistan, an effort was made to assess the air pollutants when the provincial government of the Punjab requested the Food and Agriculture Organisation (FAO) of the United Nations to investigate the problem. The report titled, Remote Sensing for Spatio-Temporal Mapping of Smog in Punjab and Identification of the Underlying Causes Using GIS Techniques (R-Smog) calculated the emissions of various sectors of Punjab, Pakistan.The report revealed that 43 percent of air pollutant emissions were coming from the transport sector. The second key sector was industry whose share was 25 percent. Agriculture, with the perspective of rice residue burning, was ranked third. It accounted for 20 percent of total air pollutant emissions. The power sector was ranked fourth. It contributed 12 percent to the emission inventory.The FAO’s study has explored the relationship between smog and the rice residue burning practices by farmers in the rice belt of the Punjab. The report says; “The smoke resulting from this rice stubble burning normally stays in the lower troposphere, below 5 km.”The report also indicates that previously farmers used rice residues as fodder for their animals before they started burning their fields, as it is the fastest and least expensive method to prepare the fields for other crops, considering the shortening of the winter season due to climate change.The report highlight that up to 88 percent of farmers interviewed would agree to respect a law banning crop residue burning if alternatives were made available.The report has assessed and subsequently mapped the aerosol point sources and arrived at the conclusion that 65 percent of the aerosol sources were originating within Pakistan, which includes biomass burning and mixed-type pollutants. From outside of Pakistan, the polluting sources were detected in India, Afghanistan and Iran.Spatio-temporal remote sensing based hotspot analysis for ten years shows that more fire events were recorded in the Indian-administered Punjab as compared to Pakistan’s Punjab.The report calls for inter-country collaboration on data sharing, monitoring and joint strategies to address the problem.A trans-border treaty on air pollution is the need of the day. Dr Abid Mehmood, a research fellow at Sustainable Places Research Institute, Cardiff University, UK, says, “The treaty would have to start with the identification of key air polluting substances and proposing ways for reducing them. The focus should later move towards emission reductions in general.” He proposes, “Joint monitoring committees and evaluation plans for sharing of data and exchange of novel methods to counter air pollution.”It is worthwhile to note that in 2017, 128,000 Pakistanis and 1.2 million Indians died from air pollution, according to State of Global Air 2019 report (https://www.stateofglobalair.org/sites/default/files/soga_2019_report.pdf).Dr. Abid Mehmood further says, “Both countries heavily rely on their agricultural produce. More recent incidences of stubble burning in bordering lands have been affecting the health and quality of life in both countries.” He stresses for a joint strategic vision to help reduce the catastrophic effects of a polluted environment.Recently, at the 2019 Climate Change Conclave organised by the Civil Society Coalition for Climate Change (CSCCC) on November 26, Senator Sherry Rehman ‘strongly agreed’ on the need for trans-boundary collaboration. “Climate knows no boundaries and we must engage India in the discussion but that can only happen if the other side wants to talk,” says the senator.Sherry Rehman has also called for raising the issue with the Foreign Affairs Committee. She says, “Few people from Pakistan are involved in engaging India in any debate. Such deliberations on transboundary collaboration can occur at UN climate conferences or International Parliamentary Forums.” Rehman also urges fixing the air pollution sources at home. “This is what we can do first,” she says.Lack of political will has been recognised as one of the major impediments. Dr Tariq Banuri, a senior expert on climate, who is also chairman of the Higher Education Commission (HEC), says, “Awareness and political commitment in both countries has been slow to emerge, and has varied with the changing governments. The current government in Pakistan has taken the issue seriously. This provides a basis for reaching out to India.”Collaboration is the key for Pakistan and India to move forward. The executive director of Civil Society Coalition for Climate Change (CSCCC), Aisha Khan, says, “It is very important for Pakistan and India to initiate a conversation on the need and modalities of how to collaborate on managing air quality standards for the benefit of people living on both sides of the border.”“A framework can only emerge when both countries first agree to address it jointly. Therefore the first step is recognition of the problem and a willingness to work on it together. Solutions follow as a result,” she adds.Khan urges both Pakistan and India to try to find bilateral solutions to problems while taking into account all factors. “Crop burning is one of the factors. Industrial and vehicular emissions and brick kilns are also major factors.” She adds, “The direction of the winds determines the flow of air from one country to the other. So attribution of blame is difficult to establish.”Aisha Khan says, “Citizens on both sides of the border have to generate the demand for finding a solution.” Khan recommends taking steps at the national level first and then calling for bilateral solutions. “The air in Lahore has become toxic and we cannot keep closing schools and businesses as a response. We have to find a solution by first taking all the steps at home to reduce pollution. Once we have done that we will be in a much better position to address trans-boundary sources.”Experts from the other side of the border also think the same. Dr Pallavi Pant, an air quality scientist from India says, “The trans-boundary air pollution problem in South Asia goes beyond crop stubble burning and calls for regional action to address major sources of air pollution.”Pant talks about various initiatives that are contributing to transboundary air pollution cooperation. “There are efforts by scientists [referring to efforts of International Centre for Integrated Mountain Development (ICIMOD) to facilitate data sharing between Pakistan and India], as well as recent efforts to set up cross-boundary air pollution monitoring programmes [referring to collaboration between Pakistan Air Quality Initiative (PAQI) in Karachi and Urban Sciences in Mumbai].”She adds, “Regional cooperative agreements will allow for collaborations, knowledge exchange and joint air pollution research and mitigation efforts.”Pant recommends the formulation of, “effective, long-term policies on air pollution control, focused on major sources such as power plants and industries, transportation, waste burning, stubble burning and dust etc.”Dr Tariq Banuri similarly recommends addressing trans-boundary air pollution crisis in South Asia through “robust national efforts, combined with international agreements on regular information sharing, solution sharing, and coordinated action if needed.”