Exploration and Conservation: SESAM Ecotox Research Lab’s New Cave Preservation Initiative “Aero Cave”

By Ysabela Calica & Daphne Encinares 

For the past few decades, Philippine caves have stood as natural resources embossed with history, unique beauty, and natural habitat for many animals. Riddled with layers and layers of research and historical artifacts to explore, cave tourism has since then become a popular exploration activity in the country

Cavinti Underground River and Caves Complex in Laguna (Cortes, 2023)

Ecotourism has since then faced the task of preserving caves and lessening disaster and destructive feasibility. 

As such, the UPLB Ecotox Research Lab has recently ventured on its Aero Cave Project, or better known as the Cave Quality Alert System (Cave Air QAS) which is designed to monitor and assess cave air quality in extreme climatic events in tropical environments. Headed by Project Leader Dr. Jessica D. Villanueve-Peyraube with Study Leader Dr. Janice B. Sevilla-Nastor along with international collaboration with geologist and hydrogeologist Dr. Nicolas Peyraube, the Aero Cave project aims to develop the AeroCave sensor network system and data acquisition prototypes. This primarily aims to create a Cave Air Quality Alert System designed to provide early warnings to researchers, cave managers, local governments units, and other stakeholders about potential hazards within the cave environment. 

Additionally, the project will investigate the applicability of the simulated and derived thresholds to inform the creation of policy and regulatory recommendations.

Why assess cave air quality?

Assessing the air quality of caves is crucial for several reasons. It serves as a foundation for improving cave management and tourism policies, ensuring the safety of tourists, cave managers, and local government units entering the caves. This monitoring system can also benefit other industries, such as mining, where air quality is vital for the welfare of workers. Additionally, it plays a significant role in preserving cultural heritage, including cave paintings and bones, similar to studies conducted in France, and in protecting the caves’ biodiversity.

The aerology of a cave, which involves both internal and external elements, is essential in understanding the interconnectedness of air and water quality. In Philippine caves, where water is often present, poor air quality can adversely affect communities that rely on these caves for their water supply, highlighting the importance of maintaining good air quality within these environments.

Cave Profiling Activity at the Cavinti Cave, Laguna with the Aero Cave Proponents

How do Caves Breathe? 

Similar to humans and other living things, caves also breathe. Different types of caves have different air flows depending on their cracks and openings. Along with temperature, all of these can contribute to the air quality inside caves. 

The Cave Air QAS Project Presentation discusses three main air flows in caves: the chimney effect, air trap, and short variations. Double entrance caves experience the chimney effect, but entering caves with only one opening during the day or summer requires caution due to poor air quality, increased humidity, and higher concentrations of carbon dioxide and radion, which can cause lung cancer.

There are five main cave air environment parameters. These are oxygen (O2), carbon dioxide (CO2), temperature, radon, and humidity.

Parameters of cave air environment and their standards

It is important to monitor all of these parameters because these will determine the state of the air environment in caves. To ensure the safety of each visit, the right level of oxygen (20.8%), carbon dioxide (0.04%), and radon (300 becquerels per cubic meter, a unit of radioactivity) should be checked first.

In the Department of Natural Resources (DENR) Handbook on Cave Classification for the Philippines, bad air is a factor in hazardous passages. This is the condition in caves where there is low oxygen, high carbon dioxide, and the presence of potentially dangerous gasses like methane. Overcrowding in caves may increase the CO2 level which can cause hypoxia, or fainting in caves, to people.

In the Philippines, some of the caves are classified as Class IC or caves with extremely hazardous conditions such as bad air, unstable ceiling, and rock breakdowns. These are Karkarato Cave and Maquera Cave in Cagayan, Butas Kabag Cave II in Laguna, and Kamantigue Cave in Batangas.

Aero Cave’s Formulation and Technology

The Aero Cave project is spearheaded by SESAM Ecotox Research Lab as the implementing institution with collaborations in the Université de Bordeaux and the Department of Environment and Natural Resources – CALABARZON. The project is also funded by the Department of Environment and Natural Resources through Foreign-Assisted and Special Project Services (FASPS).

There are several consultants contributing to the project with most specializing in electronics and communications and others focus on materials construction, GIS and modeling, and cave profiling. Full-time staff member Engr. Jasper Adrian Dwight V. Castro is primarily working on the developed Aero Cave technology: Cave Air Quality Alert System (Cave Air QAS).

Cave Air Quality Alert System (Cave Air QAS) Technology

The device’s main components are as follow:

Microcontroller board and radio module

  • This component serves as the main controller for the sensor nodes, hopper nodes, and master node. It can perform sensor readings as well as transmit radio packets wirelessly over a point-to-point communication channel.


  • These components measure the microclimate variables of interest such as temperature, relative humidity, carbon dioxide concentrations, radon concentrations, and wind velocity. 

Battery Supply Pack

  • This will provide power to each individual node as power supply is not available in the project site. 

According to Engr. Castro, the device works through its sensor nodes. “In sensor nodes, the microcontroller board will obtain microclimate variable readings from the sensors every minute or so depending on the research goal. Using the built-in radio module, the microcontroller board will transmit the sensor readings wirelessly to be received by the master node or a hopper node”.

“A hopper node is used to simply serve as a bridge between the sensor and master nodes when the sensor node is too far that its data transmissions are not properly received by the master node. In the master node, the sensor readings are stored locally and can be viewed through an LCD display. In the presence of a Wi-Fi signal, the master node will send an uplink transmission to the cloud for storage and monitoring through a third-party application.”

Sample Available Sensors

The system and device should be able to last for at least 4 to 5 years with proper maintenance. In terms of sustainability and resource consumption, the technology used is energy efficient which enables long range communication with minimal power usage. The battery packs to be used have high energy density and are rechargeable which minimizes the frequency of replacements.

Through the sensors and identification of the cave respiration factors, cave disturbances are measured through pre-disaster informed factors of cave environmental condition, water rock interactions, ecology and biodiversity, speleothems (structures in caves), and air toxicity. 

The sensors detect air quality in pressure and rain induced caves, primarily focusing on the impulse of air in the cave that pushes toward cave fractures in their respiratory activities. 

Respiratory Activity of Caves

Through the identified factors and conditions by the Cave Air QAS, AeroCave hopes to identify common patterns and recurring conditions to establish ecosystem services, governance, and valuation for cave ecosystems and neighboring ecosystems. 

“Monitoring cave air quality provides valuable data for conservation efforts. By identifying changes in air quality through time, we can better understand cave ecosystems and implement measures to protect them.” says Engr. Castro. 

Aero Cave and Ecotourism Industries in SEA

Venturing into similar ecotourism industries in SEA, India’s ecotourism has developed in the past few decades. Madhya Pradesh, also known as the heart of India, has diverse cave exploration that offers a great opportunity for cave eco-tourism in the country. With well-planned strategies focusing on sustainability, conservation, and community involvement, eco-tourism can significantly contribute to environmental preservation and the socio-economic development of India. 

Bhimbetka Caves, Madhya Pradesh

In Thailand, eco-tourism is also a growing sector. The country has natural parks, wildlife sanctuaries, and caves, specifically in Phetchaburi province. In 2019, tourism accounted for 17.64% of Thailand’s Gross Domestic Product (GDP), making it a significant contributor to the country’s economy.

Similarly, eco-tourism in the Philippines is also progressing. The Philippines has received recognition on a global scale for its ecotourism destinations due to the programs and policies related to tourism and ecotourism. Among these recognitions are UNESCO World Heritage Sites, the UNWTO Best Tourism Villages Program, the ASEAN Tourism Standards, and the Green Destination Story Awards. 

According to estimates based on GDP, the Philippine Statistics Authority stated that the direct gross value added (TDGVA) of tourism in the Philippines was expected to account for 6.2 percent of the country’s GDP in 2022. This indicates that a significant amount of the nation’s economic growth is derived from ecotourism and related activities. 

Eco-tourism is a significant asset in countries that are rich in biodiversity and natural resources, such as countries prominent in cave tourism like India, Thailand, and the Philippines. However, all of these countries encounter a problem. The increase in tourism affects the environment, so it is essential to implement policies like tourist restrictions and eco-friendly practice

Future Plans

After finishing the Cave Air Quality Alert System (Cave Air QAS) technology, the UPLB SESAM Ecotox Laboratory plans to extend their project to the people who can benefit from it. These are through conducting workshops with local government units (LGUs) that manage caves in their locality, starting with Cavinti, Laguna. Additionally, a comprehensive manual for users of the technology will be produced for further understanding of the device for future users. 

Articles and a study about the Aero Cave Project will also be published in Scopus or ISI-indexed journals. UPLB SESAM Ecotox Laboratory expects Master’s (MS) or Doctorate (PhD) degree students from UPLB-SESAM to utilize the research data for their theses or case studies. Moreover, the project aims to have science-based policy guidelines and recommendations for the direction and control of ecotourism as well as the management and protection of caves.

Through AeroCave, Ecotox Research Lab hopes to touch policy making and equipping ecotourism sites in the country to push forward a culture of exploration with preservation.


Cortes, K. (2023, August 11). Exploring Cavinti Cave (aka Cavinti Underground River and

Caves Complex) in Laguna. Tara Lets Anywhere. https://www.taraletsanywhere.com/cavinti-cave/ 

Department of Environment and Natural Resources. (2008). A Handbook on Cave 

Classification for the PHILIPPINES.


Department of Environment and Natural Resources. (n.d.). Philippine Caves. Biodiversity

Management Bureau. https://bmb.gov.ph/protected-area-development-and-management/philippine-caves/ 

Devi, S., & Farzana, S. A Study of Eco-Tourism Promotion in Phetchaburi Province.

Logarta, M. T. (2022, August 26). Caving for curiosity and conservation. Philstar.com.


Pandey, U. (2018). Cave tourism in the heart of India: a study of Madhya Pradesh. Journal of

Emerging Technologies and Innovative Research (JETIR), 5, 12.

Philippine Statistics Authority. (n.d.). Tourism contributes 6.2 percent to GDP in 2022 .