01 A tree chosen for how fast it grows
When Islamabad's original tree planting took place, in the same decade the city's grid was being drawn, the priority was simple: to give shade and greenery to a capital that had none. Paper mulberry, Broussonetia papyrifera, met that brief perfectly. It is a non-native tree, originally from East Asia, with exceptionally fast growth compared with local species.
For decades it was, literally, the green face of the capital: the species that defined much of the urban landscape of the first generations of sectors. The problem was not its capacity to grow, but something that only became evident over time and with the city's own expansion.
02 Forty thousand pollen grains per cubic metre
Paper mulberry is a dioecious species: there are male and female trees, and it is the male specimens that release the pollen. Every spring, that pollen begins to be released in early March, peaks around the third or fourth week of the month, with daily concentrations of between 35,000 and 40,000 grains per cubic metre, and falls off quickly from April onwards.
That figure — up to 40,000 grains per cubic metre in a single day — places Islamabad among the cities with the highest pollen peaks ever measured in an urban setting. It is the reason the capital has earned, in more than a few international reports, the nickname of allergy capital of the world.
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03 The link with asthma, measured with data
It is not a minor seasonal nuisance: there are clinical studies that have measured it precisely. In research on 118 patients sensitised to paper mulberry, 102 — 85% — reported a history of attacks in March. In the subsequent follow-up, 34 of those patients (28.8%) suffered at least one asthma episode in March, against only 6% among patients not sensitised to this species.
The study itself found a strong statistical correlation between the mean paper mulberry pollen count and the clinical records of asthma attacks in sensitised patients. It is not simply a shared perception: it is a pattern that repeats with the regularity of a calendar.
The tree planted to speed up the city ended up setting its own calendar: one of respiratory crises, not of blossom.
04 Thousands of trees felled every season
The authorities' response in recent years has been a sustained felling campaign. In 2025, the Capital Development Authority announced the removal of some 30,000 specimens across different parts of the city, after having already felled more than 5,000 in F-9 Park alone the previous year. The plan calls for replacing those trees with native species — loquat, guava, fig, apricot, the local mulberry — in numbers several times greater than those removed.
The decision has not been free of controversy: some defend the value of mature trees against the promise of new saplings that will take years to give equivalent shade. But the health argument, backed by the asthma studies and by an expert committee formed after a public-interest lawsuit, has carried more weight.
05 What this means for your visit
If you have respiratory allergies or diagnosed asthma, March is the month to plan carefully around, or simply avoid. If the trip is unavoidable on those dates, bring antihistamines, ask your doctor about preventive medication and, if you have asthma, do not travel without your rescue inhaler.
It is worth knowing because it changes how you read the city's greenery. The trees shading Islamabad's avenues are not an accident or a spontaneous jungle: they are the solution to a 1960s problem that, without anyone planning it, generated an entirely different problem sixty years on.
