Air pollution is the main cause of medical conditions such as asthma, bronchitis, fluctuations in blood pressure and other serious health problems. To do something about air quality in confined spaces such as the interior of vehicles, a number of issues have to be addressed: Why does the air get so bad inside compared to outside? What do we know from recent studies? Are there already any solutions to this problem? Experts at the Steinbeis Transfer Center for Systems Technology/Automotive took a close look at the key issues.
Put people in an enclosed space and at any given point in time they could be breathing air with a carbon dioxide (CO2) content of between 1,300 and 2,000 parts per million (ppm). According to DIN standards, CO2 levels should not exceed 733 ppm. More thought needs to be put into this invisible risk of poor air quality and its impact on people and animals. The aim should be to identify a simple solution to this problem that’s as cost-effective and technologically feasible as possible.
According to a study conducted last year by the World Health Organization, there are around 7 million premature deaths per year linked to air pollution. What’s most shocking about this is that 4.3 million people die each year as a result of air pollution in their own four walls at home. This means that, for the majority of people affected by this problem, air quality in an enclosed room is the main cause of their health problems. Given the fact that the average person spends 90% of their day indoors, this is perhaps not surprising. The United States Environmental Protection Agency has ascertained that the concentration of pollutants in enclosed areas is often between 2 and 5 times higher than typical measurements outdoors. All of these health problems are primarily caused by a gas that we don’t normally consider harmful: CO2.
This motivated the experts at the Steinbeis Transfer Center for Systems Technology/Automotive to look more closely into the issue of air pollution in confined spaces.
The experts pooled all available data and carried out experiments in collaboration with students. For example, the Steinbeis experts wanted to measure whether air quality improves significantly – and in what way – if a window is opened or a simple ventilation device is switched on. To do this, they developed a small control device for the experiment. The system includes sensors installed inside and outside the room and the data provided by these sensors reflects the concentration of different gases, the temperature and air humidity. If the system determines that air quality is better outside the room than inside, air is exchanged. Depending on the system, this can be carried out by simply opening a window or by activating a ventilation system.
The system also compares air currently inside the room with standard values and provides the user with feedback on whether the air quality in the affected areas is good or bad. Since the system was being investigated for subsequent introduction to use in vehicles, it includes a CAN interface. This makes it possible to integrate the unit into existing vehicles and can transmit commands directly to an existing control unit in order to manage the ventilation system.
The system can also assess whether the vehicle is moving or not, making system adjustments as necessary to adapt the behavior of the ventilation system. If the air is still, windows and flaps can be opened wider and ventilator rotation is higher than it would be if there is more wind or airflow. It is also possible to limit temperatures to minimum and maximum levels. Temperature sensors inside and outside the room allow the system to determine if airing the room will make it warmer or cooler and react in keeping with pre-defined settings. This can also help reduce the burden on heating systems or the air conditioning, which makes sense not just for financial reasons but also for the sake of the environment.
The entire system was designed to make it as inexpensive as possible to produce. The low-price sensors used by the system mean that the software has to verify data. The controllers needed to control the actuators were programmed in Python for an ARM7 processor, which is the core of the system. The system has a variety of interfaces including Bluetooth, WiFi and Ethernet. These make it possible to transfer stored data directly to a smartphone and it’s also possible to link up directly with Internet devices. Users can also store data directly on a memory stick via USB.
The system is controlled manually and indicates the quality of the air on LEDs. By linking up to smartphones or Internet devices a variety of other functions and settings can be used, such as providing more detailed information on current measurements. A closed control loop is implemented to keep room for error down to a minimum.
The Steinbeis experts believe that by combining their concept with modern smart control devices, it will be possible to create simple solutions that help minimize problems with the air quality inside vehicles.
Professor Dr.-Ing. Hermann Kull is director of the Steinbeis Transfer Center for Systems Technology/ Automotive and works with Harsha Jakkanahalli Vishnukumar on the development of control device software with a focus on the automotive industry. This involved the fundamental investigation and functionality testing of new functions in automotive construction and drive technology, as well as the development and testing of application software for industrial systems.
Professor Dr.-Ing. Hermann Kull
Harsha Jakkanahalli Vishnukumar
Steinbeis Transfer Center Systems Technology/Automotive (Esslingen)