Comfortable doesn't always mean healthy
For many professionals, the workday begins and ends in an air-conditioned environment. The cool air feels refreshing after battling traffic, heat, and pollution outside. Yet experts say that indoor air is not automatically healthier than outdoor air.
"Most people in conventional work spaces spend a minimum of 8-10 hours at their office. In a tropical country such as ours, work spaces tend to be air-conditioned, often with central units. Considering how polluted our cities have become, it is natural to assume that staying indoors in such spaces is beneficial. However, what is often underappreciated is the role that indoor air quality plays in health," said Dr Lancelot Mark Pinto, Consultant Pulmonologist and Epidemiologist at P.D. Hinduja Hospital and MRC Centre, Khar.
In fact, concerns around indoor air quality are not new. The term "sick building syndrome" was coined decades ago to describe a situation where people experience symptoms such as throat irritation, headaches, coughing, fatigue, and breathing discomfort while inside a building, but feel better after leaving it. The phenomenon has been recognized by public health experts and studied extensively in office environments. The US Environmental Protection Agency (EPA) notes that poor ventilation, indoor pollutants, and poorly maintained building systems are among the leading contributors to such complaints.
What's really floating around in office air?
The problem is not the air conditioner itself. The issue often lies in what travels through the system.
According to Dr Pinto, many office buildings recirculate air to improve energy efficiency. While this saves power, it may also keep contaminants trapped indoors.
"Air is often recirculated to improve energy efficiency. Damp humid settings can foster the growth of fungi. Ventilation circuits that are not periodically cleaned can have dust, dirt and debris, which are then circulated from the vents. Pigeon and other bird droppings in units can be aerosolized and inhaled, causing hypersensitivity reactions. Bacteria such as Legionella can thrive in air-conditioning units and cause outbreaks."
Dr Ankita Srivastava, Chief of Labs at Neuberg Diagnostics, added that poorly maintained HVAC systems can become reservoirs for microorganisms, particulate matter, and volatile organic compounds (VOCs).
Many people imagine pollution as something visible on a busy road. Yet some pollutants are invisible. Fine particles, fungal spores, bacteria, dust mites, cleaning chemicals, and allergens can all accumulate indoors. Research by the EPA has shown that indoor pollutant concentrations can sometimes be several times higher than outdoor levels, particularly in buildings with insufficient air exchange.
The subtle signs your office air may be affecting your lungs
Most people expect lung problems to show up as severe breathlessness. In reality, the early warning signs are often much easier to dismiss.
Dr Srivastava explains that symptoms can include:
Persistent dry cough
Sore throat
Eye irritation
Frequent sneezing
Breathlessness
Headaches
Repeated cold-like symptoms
Increased asthma attacks
One clue often stands out: symptoms improve after leaving the office.
"The signs of sick building syndrome include prolonged dry coughing, sore throat, breathlessness, headache, and eye irritation, along with frequent cases of upper respiratory infection symptoms in people who feel better once outside of the office," she said.
Fine particulate matter, particularly PM2.5, is a major concern because these microscopic particles can travel deep into the lungs.
"In the latter case, fine particulate matter (PM2.5) becomes a major culprit for causing subclinical inflammatory processes in the lungs as this type of particulate matter tends to penetrate into alveolar structures. Over time, such exposure may also contribute to respiratory conditions such as asthma and allergic rhinitis, particularly in individuals with predisposing sensitivities."
The EPA similarly notes that symptoms associated with poor indoor air quality often include irritation of the eyes, nose, and throat, headaches, fatigue, dizziness, and respiratory discomfort.
Why some offices become "sick buildings"
A building does not become unhealthy overnight. Often, it is the result of several small problems adding up.
Dr Pinto pointed to factors that many employees never notice.
"Carpets and floorings which are not vacuumed regularly can harbor a variety of contaminants from footwear (including animal feces), which remain trapped in a closed workspace."
He also warns about hidden triggers that are often mistaken for cleanliness.
"Strong smells such as burning incense sticks, use of air fresheners, strong cleaning solutions and pesticides can all trigger asthma."
Another overlooked factor is moisture.
"Fungi/Mold growing on damp walls need to be attended to."
Government-led research into office buildings has repeatedly found links between ventilation quality, HVAC maintenance, occupant symptoms, and indoor air quality. The EPA's Building Assessment Survey and Evaluation (BASE) study, which examined office buildings across multiple regions, was designed specifically to understand how building characteristics and ventilation systems affect employee health and comfort.
How employees and employers can protect lung health
The good news is that improving indoor air quality is often possible without major structural changes.
Dr Pinto recommended increasing fresh-air exchange whenever possible, "One should try and have air exchanges as frequently as possible rather than recirculate air."
He also noted that opening windows where feasible and using fans to improve air movement can help.
Dr Srivastava emphasizes the importance of routine maintenance.
"The temperature inside the office needs to be controlled in the range of 23–25°C and the humidity level should be maintained at 40-60%. Filter cleaning at least once in two to four weeks intervals as well as regular duct disinfection is important to avoid dust buildup in the system."
She also stresses that workplace health monitoring should become more proactive.
"For diagnosing the earliest signs of obstructive or restrictive pulmonary pathology, spirometry should be used. Another useful diagnostic test for those with signs of asthma is Fractional Exhaled Nitric Oxide (FeNO)."
Experts recommend several practical measures:
Ensure regular HVAC servicing and filter replacement.
Address damp walls and visible mold immediately.
Avoid excessive use of air fresheners and strong chemicals.
Conduct periodic indoor air quality assessments.
Encourage employees with respiratory infections to work remotely when possible.
Reduce dust-trapping materials such as carpets.
Improve ventilation and fresh-air circulation wherever feasible.
Most importantly, recurring symptoms should never be ignored simply because they occur indoors.
"It is very important to recognize that the air conditioning setting itself can be the source of a patient's exposure," said Dr Srivastava. "Early diagnosis of diseases can serve not only as a preventive measure for the progression of the same but also as a way to assure that changes are implemented in the very environment."
Medical experts consulted
This article includes expert inputs shared with TOI Health by:
Dr Lancelot Mark Pinto, Consultant Pulmonologist and Epidemiologist, P.D. Hinduja Hospital and MRC centre, Khar.
Dr Ankita Srivastava, Chief of Labs at Neuberg Diagnostics.
Inputs were used to explain how prolonged exposure to poorly maintained office air-conditioning systems can affect lung health, the hidden risks associated with indoor air quality, and the steps employees and employers can take to create healthier workspaces.
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