The sweet fragrance that Delhi inhabitants know all too well post-diwali, no we are not talking about the pollution and smoke, comes from a tree called Devil’s Tree. Around mid-October, the tree starts blooming creamy white flowers filling the air at dusk with a distinct and unmistakable fragrance. It is this scent that beckons, nay compels you to stop and take notice of the tree. But it is also this scent that is the cause of respiratory issue for thousands if not more.
The tree commonly called Saptaparna, Saptaparni, Indian Devil Tree or Scholar’s Tree and is native to India. It is now present in China, South- and South-east Asia and Australia. Its English names “scholar’s tree” and “blackboard tree” refer to its use in making school black boards and wooden slates for children to write on. Its other name “devil tree” or “shaitan ka jhad” is based on the belief in Western India, that the tree is an abode of evil spirits..
In the past decade the tree has become a bone of contention for people who suffer for asthma or those who have pollen-allergy.
“Not all green is good for human beings”
So what exactly is in the scent that causes so many problems?
In a study from Vietnam, more than 34 components were identified, representing 92.5% of the oil. The major portion (35.7%) is made up of linalool, a terpene alcohol found in over 200 plant species, mainly in flowers (e.g., lavender, sweet basil and hops) and spices. Other major ingredients included cis- and trans-linalool oxides (14.7%), α-terpineol (12.3%), 2-phenylethyl acetate (6.3%) and terpinen-4-ol (5.3%). More than 90% of the volatile aroma compounds were oxygenated, and together contributed to its fragrant odour.
Now, Linalool is found naturally in other flowers as well such as lavender, mint, and other plants. Linalool breaks down when it comes into contact with oxygen, it becomes oxidized and can cause allergy. Is known to cause skin allergies for atleast 5-7% population. Especially the oxides. Linool and its oxides make up about 50.4% of the frangrance.
Not just NCR that suffers
In Pingtung City, Taipei, residents complained of feeling nauseous and headaches caused by the Indian Devil’s Tree. Officials from the Pingtung City Public Works Bureau said they receive a large amount of complaints during the tree’s flowering and seeding seasons. As a result, Alstonia Scholaris trees were chopped down because the residents would complain of nausea, difficulty breathing and trouble sleeping because of the fragrance released by the tree.
The residents’ of the city had enough of the tree and demanded that the odour emitters be cut down. They said that if the city government could not find a solution, they would demand compensation from the central government for the psychological and physical damage they had suffered due to the trees.
The first documented issue of allergies to the tree in India was in 1992 when 10 trees had to be felled in IIT Kanpur. The IIT campus has nearly a thousand tall, evergreen Alstonias. After several staff members complained of asthma attacks, some trees were chopped down,however the environmentally conscious staff members raised an outcry.
A B Singh, an allergy expert at the Centre for Biochemicals (CB) in New Delhi, however, claims that there are as yet no studies indicating that Alstonia pollen is an allergen. But he indicates a number of trees that do stimulate allergic reactions in susceptible individuals. He complains that numerous exotic trees are nonetheless being planted under afforestation programmes without evaluating them for their allergen potential.
Singh cites the example of mulberry (Morus alba) which is planted extensively in India while, because of its allergenic pollen, its plantation is prohibited in certain arid regions in USA. “Not all green is good for human beings”, he emphasises. Now this is a major in India, around 20-30% of the population is reported to be afflicted with an allergic rhinitis. and 10-15 % are estimated to suffer from bronchial asthma.
In Noida alone, as per the department records, there are around five lakh Alstonia trees, planted on the lines of trees at Rajghat. Around 2007,the department realised that the tree causes problems for asthma patients. “If asthma patients stand near the tree for a longer time, they could develop breathing problems. We want to make the city people and environment friendly. The effort is to plant trees like Indian rosewood (Sheeshum), Jambul, White fig and Cassia Fistula-Amaltas,” said the official at the Horticulture department of Noida. Thus, In 2010 the Horticulture department of Noida decided to put the plantation of Alstonia scholaris trees on hold for now.
The reason these trees were planted is that this tree is able to form leafy canopies that create shade in just a couple of years. Few decades ago, the pollution levels were not as high as they are today. More people have dust, pollen and linool allergies now than they did ever before. The percentage of population with asthma has increased from 4% in 1992 to 20-30% in 2015. All these reasons coupled together have made the scent of this tree a cause of breathing difficulties and choking-sensation for people with allergies.
So what is the solution?
The obvious one is to not plant this tree. But whats important is how we deal with the trees that are already blooming? In Taipei, the government official had advised that citizens trim the leaves and branches just before the flowering season (October – December) because this can prevent the release of the irritable odour and seedlings. If the community has funds, it is better to plant trees that will not cause allergies and add to the already existing woes of people struggling with extremely polluted air.