"A central air-conditioning system can be notorious..."

Dr Sujeet Rajan is a practising respiratory physician, who works for Bhatia Hospital and Bombay Hospital Institute of Medical Sciences in Mumbai, India. He is conducting a research on asthma practice methods in primary care, and has delivered lectures all over the world including at the Arab Health Conference and Al Maktoum Medical College in Dubai.

GN Focus caught up with him for a quick chat:

Is air conditioning bad for homes?
In hot and humid climates, air conditioning is a boon. However, it comes with its drawbacks — dry skin and a lot of airway allergies exacerbating because cold air acts as an allergic trigger.

Does air conditioning aggravate conditions such as allergic rhinitis (allergic colds) and asthma?
Air conditioning is certainly not banned for these conditions! In fact, most patients with these conditions tolerate air conditioning quite well. However, we need to realise that our body temperature is usually close to 37°C most of the time, and the temperature in a well air-conditioned room is usually close to 22°C or 23°C. This cold air is usually warmed by the upper respiratory tract before it enters the lower respiratory tract (bronchial tubes in the lung). So we don't feel this effect at all.

But in those sensitive to cold air or who sit next to an AC blast for most of the day, the effects can be quite debilitating.

Can air conditioning worsen asthma in any other way?
Yes, fungus accumulates in the filter of air conditioners. The latter needs to be changed every three to six months. Fungal sensitisation can aggravate asthma attacks.

And can air conditioning cause infections?
Not directly, though a central air-conditioning system can be notorious for spreading legionella pneumophila infection. This pneumonia, unlike typical pneumonias presents with fever, body aches and joint pains, is difficult to diagnose with usual sputum culture methods and needs a urinary antigen test. There is often a multi-system involvement, and more than one person is usually affected, often in a break-out. The organism has been known to harbour in poorly serviced central air-conditioning systems but mainly grows in water. Most patients respond to the macrolide (erythromycin) group of antibiotics in a positive manner.

And what's the link between pigeons and hypersensitivity pneumonitis (HP)?
HP is a type of ‘allergic pneumonia', often due to an antigenic culprit in the home environment such as damp walls (breeding fungus), pets at home, cement dust and often exposure to diesel exhausts or generator gases. Pigeon dust is also notorious, and patients suffering have often been known to be proximal to pigeons, and often give a history of feeding pigeons themselves. Pigeons are known to roost around window ACs and hence, a susceptible person can develop HP from the situation. But fortunately, not everyone is prone.

HP presents with a dry cough, breathlessness and rarely fever. If the patient is quite breathless and coughs a lot, he may need a high-resolution CT scan and, on occasion, a lung biopsy to confirm the same before starting him on steroid tablets for at least six months to a year.

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How to make your air conditioner work in your favour

Respiratory physician Dr Sujeet Rajan chalks out some pointers for GN Focus readers:

i) Keep your home clutter-free.

ii) Don't keep too many pets.

iii) Avoid staying close to construction sites.

iv) Service your ACs regularly.

v) Never sleep or work close to the direct blast of an AC.

— S.N.