Most factory work falls into the light-work category (14\u201325\u00b0C) or directly into intense physical work, for which the Royal Decree does not provide a number. Here\u2019s the nuance almost nobody explains: those ranges are intended for workplaces, and the RD itself clarifies that they do not apply to areas where, due to the activity, it is not possible to maintain them. A foundry or a plant with furnaces is never going to be at 25\u00b0C, and the law assumes that. <\/p>\n
Why isn\u2019t there a fixed maximum temperature in a factory?<\/h2>\n
Because industrial work is rarely sedentary and because process heat makes it impossible to apply a rigid cap. In a facility with machinery, furnaces, welding, or presses, the temperature is set by the activity itself, not a thermostat. That\u2019s why the regulation changes approach: instead of imposing a number, it requires the company to assess the risk of heat stress and adopt measures so conditions do not harm health. <\/p>\n
The National Institute for Safety and Health at Work (INSST) uses indices such as WBGT (wet bulb globe temperature) to assess whether a heat situation is dangerous, combining temperature, humidity, radiation, and effort. It\u2019s a more accurate way to measure real risk than a simple thermometer reading. The practical conclusion for a factory is clear: it\u2019s not enough to look at ambient temperature\u2014you have to assess the whole picture and act if the result exceeds safe thresholds. <\/p>\n
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Humidity and air currents: the other two limits set by the regulations<\/h2>\n
In addition to temperature, RD 486\/1997 regulates relative humidity and air speed, two factors that directly affect how hot it feels. Relative humidity must be kept between 30% and 70% (or not drop below 50% where there is a risk of static electricity). <\/p>\n
As for air currents, the regulation sets maximum speeds to avoid discomfort: 0.25 m\/s in non-hot environments, 0.5 m\/s for sedentary work in hot environments, and 0.75 m\/s for non-sedentary work. There\u2019s an important detail for factories: these limits do not apply to air generated by fans or air conditioning used specifically to combat heat, where the cap becomes 0.25 m\/s for sedentary work and 0.35 m\/s for the rest. In other words, the law anticipates and allows the use of air conditioning and forced ventilation to protect workers from heat. <\/p>\n
What the company must do when safe temperatures are exceeded<\/h2>\n
Since 2023, Royal Decree-Law 4\/2023 has strengthened employers\u2019 obligations in the face of extreme heat. When AEMET issues an orange or red warning for high temperatures and the risk cannot be controlled with other measures, the company must adapt or reduce the working day, and may even have to stop tasks that pose a danger to the worker. <\/p>\n
This obligation mainly applies to outdoor work, but the underlying principle applies to any workplace: if the risk assessment detects heat danger and the company does not correct it, it is in breach of the Occupational Risk Prevention Law, which is punishable. Required measures range from reorganizing schedules and breaks to ensuring cool water, breathable clothing, and, when heat is structural, technical means to lower the temperature at the workstation. The regulations don\u2019t just warn about the risk\u2014they require action. <\/p>\n
What happens above certain temperatures: risks to health and production<\/h2>\n
Above 26\u201328\u00b0C with physical effort, performance and safety begin to drop in measurable ways. The body works to maintain its internal 37\u00b0C and, when it can\u2019t, fatigue, loss of concentration, cramps, and, at the extreme, heatstroke can appear\u2014 a medical emergency that occurs when body temperature exceeds 40\u00b0C. <\/p>\n
For the company, this has two sides. On the one hand, the operator\u2019s health and legal responsibility. On the other, productivity: an overheated worker makes more mistakes, performs worse after half a shift, and increases the risk of accidents with machinery. In a machining or welding workshop, keeping the workstation within a reasonable range isn\u2019t just about complying with the law\u2014it\u2019s about protecting production. <\/p>\n
How to keep the factory within safe temperatures<\/h2>\n
The realistic way to control temperature in a factory is usually not to air-condition the entire building, but to cool the workstations where heat affects people. Fully air-conditioning a high-ceiling facility with doors opening and machinery generating heat is expensive and inefficient, and often not feasible. <\/p>\n
The alternative more and more workshops are using is to direct cooling to the operator. A portable industrial air conditioner<\/a> cools the workstation without construction or installation, works in environments up to 45\u00b0C, and solves the critical point (the person) without the cost of cooling thousands of cubic meters. Depending on the type of facility, an evaporative cooler or high-volume fans can be even more energy-efficient. Combined with the organizational measures required by law (breaks, hydration, rotation), these solutions help keep conditions within a safe range. <\/p>\nCool the workstation and comply with the regulations<\/h2>\n