Brasília and much of the Midwest experience periods when relative humidity drops below levels considered safe by the World Health Organization. The WHO recommends that relative humidity remain between 40% and 70% to maintain respiratory health. During dry seasons, the Federal District has recorded humidity levels as low as 9%, even below desert levels. When this air enters homes, offices, and hospital settings, its impact accumulates in the human body and requires technical attention to mitigate effects on the respiratory system.
How dry air affects the body
Low humidity dries out the mucous membranes of the airways, reduces the efficiency of the cilia responsible for filtering inhaled particles, and makes it easier for viruses and bacteria to enter the body. Common symptoms include nasal irritation, a dry throat, a persistent cough, bleeding in the airways, and worsening of asthma, rhinitis, and bronchitis. Children, the elderly, and people with chronic respiratory diseases are at the highest risk.
At the same time, the dry climate increases the presence of airborne dust and the feeling of discomfort indoors. When the burning season coincides with the dry season, the situation worsens: fine particulate matter adds to the already dry air, further compromising respiratory function.
How air conditioning works in this scenario
Proper climate control goes beyond temperature regulation. During periods of low humidity, the system must address three issues simultaneously: maintaining thermal comfort, controlling relative humidity, and ensuring air exchange with adequate filtration. Patrick Galletti, a mechatronics engineer and CEO of Grupo RETEC, notes that treating the environment solely based on temperature—without considering humidity and air exchange—makes indoor air just as problematic as outdoor air.
Conventional air conditioning equipment reduces air humidity during cooling. In environments where humidity levels are already very low, this exacerbates the problem. Solutions such as humidifiers in specific rooms, systems with integrated humidity control, and air treatment with fine filtration provide more consistent results than standalone equipment.
What to Consider in Residential Settings
During dry seasons, using humidifiers in bedrooms and rooms where people spend extended periods of time reduces the direct impact on the respiratory tract. When selecting equipment, consider the airflow rate, room volume, and proper maintenance of the water reservoir, as poorly sanitized humidifiers can become a source of mold and bacteria.
At the same time, habits such as frequent hydration, nasal rinsing with saline solution, and reducing exposure to outdoor air during peak pollution hours complement the benefits of a climate-controlled environment. No equipment can replace these basic precautions, but taking a multifaceted approach reduces the risk of acute conditions.
What to Consider in Corporate and Hospital Settings
In offices, schools, hospitals, and clinics, precise control of temperature, humidity, and air exchange is an integral part of the HVAC design. Systems with air handling units (AHUs) allow for the combination of cooling, filtration, and humidity control, maintaining the indoor environment within an appropriate range even when the outdoor air is extremely dry. In hospitals, this is a regulatory requirement. In offices, proper system operation reduces absenteeism, productivity losses, and complaints related to air quality.
Outdoor air ventilation requires extra care during periods of drought combined with wildfires. Outdoor air must be treated before entering the building, with filtration capable of handling the particulate matter present in the atmosphere. Systems that are improperly sized or have overdue maintenance lose this protective capability.
Practical Tips for the Dry Season
- - Check the relative humidity indoors using hygrometers, especially in homes and offices.
- - Evaluate the use of humidifiers compatible with the volume of the space.
- - Check filters and perform maintenance on HVAC systems.
- - In corporate and hospital construction projects, review the performance of air handling units and their air exchange capacity.
- - During wildfire seasons, increase filtration at outdoor air intakes.
RETEC provides solutions for air conditioning, ventilation, exhaust, and air treatment in residential and corporate settings, as well as for medium- and large-scale construction projects. For projects with technical requirements for humidity control and air quality, please contact the sales team.
We were featured in an article on this topic in Correio Braziliense (Fabiano Moraes’ column). The article, which addressed the effects of dry weather on respiratory health and the role of air conditioning, included comments from Patrick Galletti, CEO of Grupo RETEC. Read it at: https://www.correiobraziliense.com.br/colunistas/fabiano-moraes/2025/06/7187560-clima-seco-e-climatizacao-como-preservar-a-saude-respiratoria.html