As a seemingly infinite spell of smog continues to suffocate the denizens of Lahore, we need to understand that air pollution in Lahore is not seasonal, but rather perennial. Our over-reliance on personal automobiles, and the infrastructure to support them is contributing to millions of toxic particulates in the air, making breathing hazardous, and our respiratory futures uncertain. We are uncertain about what we breathe, and our shortsightedness has led us to focus on ad hoc solutions that serve merely as a band aid on our festering air crisis.

Our city of Lahore constantly flits around between the top two spots on the lists of cities with the most air pollution. This has become a source of ignominy for the country and a dire health hazard for its citizens who have no choice but to immerse their lungs in the impure terrarium that is their city. A number of studies have been done on the levels of pollution. However, there has not been an in-depth study of what it is that we are exactly breathing as we go about in our daily commutes. PM levels reported by conventional, mass-based metric systems are real-time, but they fail to consider the complex chemical compositions, particle morphologies and the interactions of particulates that happen at the microscopic level. In a study done at the University of Cambridge, my co-authors and I attempt to dispel some of the mystery behind the sources of air pollution using magnetic and chemical techniques that have not been adopted for research in Lahore.

For our study, we decided to apply a passive, bio-magnetic monitoring technique. Atmospheric particulates tend to accumulate on exposed biological proxies (such as leaves or tree barks). These proxies can also contain magnetic minerals that may be used to provide temporal and/ or spatial information on air quality. In our experiment, tree leaves were chosen from a sampling site next to Canal Bank Road for identifying the presence of different particulates - both anthropogenic and non-anthropogenic (Fig. 1). We observed spatial and temporal variation in magnetic signals in tree crowns next to the road at inhalation level. Spatially, this means that leaves near the road had a higher pollution loading, which decreased as we moved away from the road. Temporally, we observed that exposing leaves over time resulted in accumulation of both anthropogenic and non-anthropogenic particulates.

The largest weight fraction of particulates in Lahore’s air features mineral dust (Fig. 2). This dust is non-anthropogenic in nature and may be due to the semi-arid climate of the region. There is little we can do to effectively combat this at its source. Instead it is more important to focus on the air particulates that are due to human activity in Lahore. These particles primarily originate from car, bike and rickshaw exhaust-pipes, and from other oft-forgotten sources such as brake abrasion dust and tyre abrasion dust. These particles are rich in iron oxide and often associated with other heavy metals such as manganese, antimony, copper, nickel etc. The worst of these particulates are the ultrafine (<0.1 um) particles that pose a serious health concern and are well documented in literature, as these are minute enough to be inhaled and even transported to every organ of our body through our bloodstream.

When it comes to considering sources of particulates, it is important to understand that some particles are worse than others in terms of health implications. Lahore’s air is abundant in iron-rich nanoparticles originating from different vehicular and industrial sources. Epidemiological studies have shown the association of exposure to air pollution to health implications, aggravating respiratory and cardiovascular illnesses. Previous studies in Mexico have associated exposure to iron rich, magnetic nanoparticles (ultrafine particles) with cardiac damage. More than one-third of Pakistan’s population lives in urban areas and for a country which is already showing alarming numbers of cardiovascular and pulmonary diseases, bad air quality in cities only increases that risk. This has the potential for developing into a public health crisis that our current medical infrastructure is ill-equipped to handle.

We also found an abundance of carbonaceous particles which could be potentially related to biomass residue burning, brick kilns, fuelwood burning, vehicular emissions or nearby industrial processes. Other anthropogenic particles included heavy metals and calcium carbonate particles and could have been related to the coal power plant in Raiwind, construction industry and industries in Quaid-i-Azam or Sundar Industrial Estate. A study has shown heavy metal traces in PM can have implications for human lung epithelial cells because of their higher toxicity levels. Compelling evidence from epidemiological and toxicological studies highlight the absolute need for a concerted effort to reduce exposure to such a toxic mixture of particles.

City authorities and citizens have already attempted to push measures to alleviate the severity of the problem, but we need to be careful that we spend our modicum of resources on solutions that can give us the most impact. One such solution has been the plantation of bottlebrush trees along the roads such as Canal Bank Road where my study was conducted. Although the presence of bottlebrush trees on Canal Bank Road did reduce particulate concentrations away from the road, without further data we cannot conclude whether this is due to a ‘screening effect’ of trees or reduced air flow in the street canyon. Some scientific studies have argued that having an ideal height and sparse density of tree crowns can ‘filter’ particulates as they allow air to flow freely through trees. There is a need for extensive studies on whether bottlebrush species or (any other for that matter) can reduce exposure to particulates by acting as filters because of their sparse tree crown density. Having more quantitative data about such a solution would be a boon to policy makers and city officials.

Promoting cycling is often presented as a panacea to Lahore’s pollution problems but it is difficult to believe that investing in cycling infrastructure would produce returns. The weather in Lahore is either too hot for the majority of the summer, or too cold in the winter for residents to adopt biking as a solution. Furthermore, Lahore is sprawling and most of our zoning has been done in such a way that most of Lahore’s commuters need to cycle vast distances to go from residence to work and vice versa. This only serves to shift the burden on a populace that already works much longer hours than most of the developed world where cycling is in vogue. Additionally, it would require a massive cultural shift in our upper and middle class to get them to adopt cycling, a practice that is currently seen as a means only for those so poor they cannot purchase motor vehicles. Finally, cyclists would be the most exposed to air pollution (along with the already exposed pedestrians), if private car use is not reduced.

The economic and social costs associated with Lahore’s polluted air are monumentally high and undocumented. The solutions with the most impact are going to be the ones that tackle the problem at the vehicular level. The city government would reap dividends if it shifted focus towards investing and incentivising mass transit. Mass transit may be the most effective measure in terms of reducing the number of private car use on the roads of Lahore. Increased public transport use would reduce not only air pollution but also CO2 emissions (that are responsible for the warming of our planet). And, if we are to shift to electric buses, that would be grand.

The planning of Miyawaki forest in Liberty is also a welcome first step towards adding greenery and freshness to the burdened cityscape. While these are absolutely required in our cities, an oft-overlooked point is that urban forests have a limited area of effect when it comes to pollution exposure. The exposure to particulates is local, and unless there are huge swathes of forests in every locality in Lahore filtering out air particulates, the impact of urban forests is going to be minimal. A resident of Samanabad would find no relief from vehicular particulates due to planting of forests in Liberty. This solution alone would not offer the denizens of Lahore much relief.

The absence of proper air quality data also means that policymakers have inadequate data for designing policies to mitigate air pollution in Lahore. The Environment Protection Department (EPD) has four monitors around a city of fifteen million people which is insufficient. Moreover, there is no description of what metrics go into the Punjab’s own air quality index - which seems quite lax to the widely used US AQI. The absence of rigour from the local government puts the health and well-being of Lahoris in the backseat. To supplement our monitoring, we also need bio-magnetic techniques in cities like Lahore (that lack a proper air monitoring infrastructure) to provide a cost-effective way to monitor and characterise the changing balance of future air particulates mix. The ‘passive’ biomagnetic monitoring technique shows correlation of cumulative PM2.5 concentration with magnetic values over time (Fig. 3) but it does not come without its limitation where meteorological conditions, or leaf morphology would influence these results.

We can also copy odd-even regulations from other cities, such as Paris, which banned cars with even number plates on certain days. This can also help in reducing the number of cars and incentivise people to carpool or take public transport. Although care needs to be taken so that citizens have avenues of public transport before such a feature is implemented lest well-meaning city officials draw their ire. Finally, we need to fund more source apportionment studies in different microenvironments around Lahore and other cities in Pakistan to better gauge the specifics of the particles we breathe. This would allow us to better respond to the health crisis that is invariably going to happen in the different localities of Lahore.

If we are to tackle climate change and air pollution, it is imperative that we work on reducing traffic in urban centres of the country. We need to seriously question our existing air quality monitoring infrastructure and top emitters if we are to come out of this abyss.

The writer is a PhD student at University of Cambridge. His research focuses on characterising anthropogenic air pollution particulates in urban macroenvironments. He’s interested in climate change, air pollution and policy. Twitter: hassanaftabs