Call for Action to Protect Hay Fever Sufferers on the High Road

Shedding season for London Planes causing discomfort for many

The canopy of trees along the High Road is currently shedding pollen and fibres

April 22, 2026

Each spring, Chiswick's trees shed a cloud of pollen and microscopic fibres that leave residents coughing, sneezing and rubbing their eyes. This year, local councillors are demanding action to reduce the impact particular on those who already suffer from hay fever.

The magnificent London plane trees lining the High Road — a species which accounts for roughly a fifth of all street trees in London — are in the midst of their annual shedding season. From mid-March through to early summer, they release two distinct waves of irritants: allergenic pollen first, followed by a shower of trichomes, the tiny, hooked, hair-like fibres that coat their young leaves and seed pods.

It is the trichomes — sometimes compared to microscopic itching powder — that cause perhaps the more insidious problem. Unlike pollen, which triggers a conventional immune response, these stiff fibres are a purely mechanical irritant, scratching their way into the respiratory tract and eyes of even perfectly healthy people. The phenomenon is well enough known among Londoners to have earned its own name: the "Chelsea Cough."

The three Conservative candidates for Chiswick Gunnersbury ward — Joanna Biddolph, Ron Mushiso and Vickram Grewal — have written formally to Hounslow Council's cabinet member for street cleaning, Cllr Shivraj Grewal, demanding that mechanical road sweepers be urgently deployed along Chiswick High Road.

Their request is specific: a thorough sweep, ideally late at night when the road is clear of traffic, using vacuum-based mechanical equipment rather than brush sweepers, which risk redistributing the fine particles rather than removing them. Workers, they say, should be provided with protective clothing and masks. The operation should then be repeated daily until the shedding season is over.

London planes make up a high proportion of the trees on Chiswick High Road

The case for acting promptly is not merely one of comfort. The pollen and trichomes that collect in gutters, along pavement edges and in the cycle lane become a secondary source of airborne irritants whenever disturbed — by passing vehicles, cyclists, pedestrians, or a brisk spring wind. The longer the material sits, the more opportunities there are for it to be re-suspended in the air people are breathing.

"It's about minimising the effect it might have and ensuring that Chiswick High Road is as pleasant and enjoyable as it is possible to be, even during this annual occurrence," the three councillors said in a joint statement.

Tree seeds deposited on Chiswick High Road

The High Road's traders — and in particular those who work outdoors, such as fruit, vegetable and flower stall holders — are exposed to the irritants throughout the working day. The councillors note that local businesses are already navigating a difficult economic climate, and anything that deters shoppers from venturing onto the High Road represents a further unwelcome pressure.

Cllr Peter Thompson, leader of the Conservative group on Hounslow Council, has said that, if the measures are adopted, the party would ensure mechanical sweeping is formally programmed into the street cleaning schedule every year going forward. "It can't be avoided," he acknowledged, "and I feel particularly badly for residents with hay fever and for our traders, such as our flower and fruit and veg stall holders, who have to work outside in it all day long."

Asked for its response, Hounslow Council said it currently sweeps Chiswick High Road weekly with a heavy mechanical sweeper, and is exploring whether this can be increased to three times a week during the shedding season.

The council also noted that London plane trees are no longer pruned once they are in full leaf — typically by the end of April — in order to avoid dislodging seed pods and trichomes. It acknowledged, however, that natural shedding on windy days cannot be prevented.

The London plane's dominance on the capital's streets is no accident. Introduced centuries ago, the species thrives in urban conditions, famously shedding its bark — and, with it, accumulated soot and pollution — to keep its surface clean. Mature specimens are among the most effective carbon-sequestering trees available to city planners: a single large plane is said to provide the cooling equivalent of ten air conditioning units, making them a significant tool against the urban heat island effect.

Recognising this, organisations such as Transport for London are now applying a "10-20-30" rule to new tree planting — stipulating that no single species should account for more than ten per cent of the urban canopy — which will, over time, dilute the concentration of plane tree irritants in any given area.