As the colder months arrive, offices across India and the world often shift their HVAC (heating-ventilation-air-conditioning) systems into a heating or recirculation mode. While the comfort of a warm, temperature-controlled office may be reassuring, the very air-conditioning (AC) and ventilation systems that keep us cosy may also be sneaking in health risks. Indoor environmental quality (IEQ) in modern offices is increasingly being recognised as a factor in worker health, productivity, and wellbeing. Recent research shows that office AC systems, when poorly designed, maintained or operated, can lead to stale air, inadequate fresh air exchange, low humidity, accumulation of pollutants and even respiratory irritation or "sick-building syndrome" symptoms.
A large review on indoor environmental quality in offices found that ventilation, filtration and thermal conditions significantly affect health outcomes. For office workers who spend the bulk of their day indoors, the combination of winter recirculation, closed windows and AC systems can inadvertently degrade air quality.
So, here's how office AC use during winter can affect health, what the science shows, and what practical steps workers and organisations can take to stay healthy and productive.
How AC Systems In Winter May Degrade Indoor Air Quality
- Many modern offices rely heavily on HVAC systems that recirculate indoor air to conserve energy in winter, thereby reducing fresh outdoor-air exchange. According to the US Environmental Protection Agency (EPA), indoor pollutant levels can exceed outdoor levels in poorly ventilated buildings.
- Low humidity is common in heated indoor environments. One review found that very low relative humidity (below 30%) can irritate mucous membranes and increase susceptibility to respiratory infections.
- AC systems may trap or fail to filter indoor pollutants (dust, VOCs, bio-aerosols), and stagnant indoor air can contribute to the so-called "sick building syndrome" with symptoms such as eye, nose or throat irritation, headache, fatigue.
- A 2023 study comparing office buildings with different ventilation mechanisms found that buildings with lower ventilation rates had poorer indoor air quality indicators and higher occupant symptoms.
What Health Issues Are Linked To Indoor AC In Offices
- Respiratory irritation: Dry indoor air, recycled air and pollutant build-up can cause irritation of eyes, nose and throat. A large review on office indoor environmental quality found links between IEQ and upper-airway symptoms, increased absenteeism and lower productivity.
- Reduced cognitive performance: Poor ventilation and higher CO2, particulate or volatile pollutants in offices are associated with slower cognitive response and decreased task performance.
- Allergy and asthma exacerbation: Low ventilation and higher bio-aerosol levels in closed spaces can trigger allergies and asthma in susceptible individuals.
- Sick-building syndrome: When building occupants experience symptoms while inside, which improve when they leave, the building environment (including AC) is implicated.
Why Winter Office AC Is Especially Tricky In India
- In many Indian offices, winter means switching off fresh-air inlets or reducing outdoor-air exchange to save energy and maintain warmth. But this reduces dilution of indoor pollutants and leads to stale air.
- External air pollution in cities like Delhi-NCR might be high (especially in cities), so occupants assume that closing windows and relying on AC is safer. Yet if AC recirculates pollutants and indoor emissions, risks remain.
- Humidity may drop significantly indoors when heating is used without humidification, leading to dryness, irritation and weaker mucosal defence.
- Many office AC systems may have limited maintenance, dirty filters or inadequate fresh-air intake, adding to indoor air-quality problems.
Provide guidance to workers so that they hydrate
Photo Credit: Pexels
What Organisations And Workers Should Do
- Ensure HVAC systems are designed and operated with adequate fresh-air exchange as per standards (for example, the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standard 62.1 for ventilation).
- Maintain filters and ducts regularly, check for mould, condensation and ensure no petrod or VOC sources are stuck in recirculated air.
- Monitor relative humidity in office spaces. Aim for 30-50% where possible and consider humidification if too low, helping mucosal health.
- Encourage occasional fresh-air flushing through opening windows for a short period when outdoor air allows, or boosting fresh-air intake periodically.
- Provide guidance to workers so that they hydrate, avoid staying in one enclosed zone too long, adjust clothing layers, place plants cautiously (they help little for high-volume pollutant removal but add comfort).
- For workers: If you feel symptoms of dryness, throat/eye irritation, fatigue in the office environment, speak to facility management about ventilation and AC settings. Also consider personal measures like desk-based humidifier, filter mask when air flows feel stale, or taking short breaks with fresh air.
Office air conditioning in winter is not a guarantee of health. While it keeps you warm and comfortable, without adequate design, maintenance and fresh-air exchange it can degrade indoor air quality and impactful health. From irritation and fatigue to reduced performance and potential chronic risks, the indoor climate matters just as much as outdoor. The good news: Many issues are preventable with vigilance and action. For organisations and workers alike, prioritising ventilation, indoor-air monitoring, humidity control and worker awareness can turn the office from a hidden hazard into a healthier, more productive environment this winter.
Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your doctor for more information. NDTV does not claim responsibility for this information.
