How to Make Public Busses Safer and Healthier (Case Study)-Aura Air

How to Make Public Busses Safer and Healthier (Case Study)


Aura Air and Delos Australia teamed up to find a solution for maintaining the health and safety of passengers and employees with advanced air purification systems. In July 2021, Aura Air provided Delos real-time indoor air quality data from two busses, both with similar conditions in terms of routes and maintenance, but only one of them was outfitted with Aura Air’s devices. Its system measured AQI (air quality index), VOC, PM2.5, PM10, temperature, and humidity levels, discovering a significant improvement in the bus’s air quality. It provided Delos Australia with a clear proof-of-concept on how air purification can improve air quality in public buses.

The Challenge

The transportation industry faces many challenges in today’s rapidly changing world. When COVID-19 hit, protecting passengers and staff’s health became a primary concern and a critical factor in keeping a core transportation system operational to fuel the economy. 


Delos' primary goals focused on restoring public confidence in ComfortDelGro Corporation’s (CDC) public transport buses and the industry in general, improving workplaces with safer and healthier working conditions, and enhancing public health and safety by installing advanced air filtration in 2500 buses. 


Because of the specifications of the transportation industry, air purifiers that connect to an electrical outlet and stand on the ground would not be appropriate for this project. Easy and secure installation with a mounting bracket was a top requirement for the project, as well as easy maintenance, automatic monitoring, and filter cleaning notifications. With its compact dimensions and weight, low energy consumption, and no maintenance required, Aura Air was able to fill all the requirements, making it well-suited to small spaces such as buses.

Aura Air Air purifier on bus
I​​mage from company


Delos Australia is a wellness real estate and technology company that offers an array of evidence-based technology and solutions for residential and commercial spaces. Delos is the founder of the WELL Building Standard™, the premier standard for buildings, interior spaces, and communities seeking to implement, validate and measure features that support and advance human health and wellness.


Delos compared over 80 products available in the U.S. and Australian markets for this project. After carefully evaluating each of them, the company selected Aura Air devices to remove particulate matter (PM2.5, PM10) effectively, total volatile organic compounds (TVOCs), and microorganisms without generating harmful by-products such as ozone.


Provide a comprehensive solution for improving and managing the air quality in public buses while increasing awareness of air quality in the entire city public transport. The pilot was executed through an interactive data-based approach providing real-time data and recommendations for indoor air quality management.

Work Process

Between July 2nd and July 28th, 2021, a pilot was conducted on two CDC city busses, one of which was fitted with an Aura Air unit. The two buses were provided with similar conditions, drove the same route, and were cleaned at the same frequency each day. Aura Air’s system measured the following parameters: VOC, PM2.5, PM10, temperature, humidity, and AQI, to provide a comprehensive report.

Bus #1 - CDC bus with no Aura Air units.

Bus #2 - CDC bus with 2 Aura Air units installed.

Sensor #1 - 3rd party sensor on Bus #1.

Sensor #2 - 3rd party sensor on Bus #2.


Case study results
Aura ​​Air

The most significant effect was a reduction of VOC levels in the air. on Bus #1, the average VOC level was 4023 ppb, whereas VOC levels on Bus #2 were 1015 ppb, a 75% decrease on average. Aura Air units were also able to prevent VOC high-level peaks from reaching high values; maximum values at Bus # reached more than 50k ppb, whereas, on Bus #2, the VOC levels did not surpass the 16k ppb bar.


Looking at PM 10 values, there was a 12.2%reduction that lowered levels from an average of 9.8 ppb to an average of  8.6 ppb. More importantly, we see a reduction in peak duration and, therefore, a decrease in the time of exposure to pollutant substances.


A similar trend can be spotted in the PM 2.5 parameters with a reduction in average levels of PM 2.5 of 12%, from 8.3 ppb on Bus#1 to 7.3 ppb on Bus #2.


As presented below, The AQI on Bus #2 (with Aura Air) has a significantly lower baseline of pollution. In the absolute majority of the time, the AQI on bus #2 is better by 54% than the AQI on Bus #1. The graph also demonstrates that on Bus #2, the number of hazardous conditions peaks is significantly lower. Not only does Aura Air performs air treatment, but it’s also used as a pre-emptive tool and helps avoid hazardous air quality on the bus.


Given these findings and based on Aura Air’s proven ability to deliver 200.7 cubic meters of filtered clean air per hour, Delos recommends that every average bus with dimensions of 13.7mL*3mW*2.4m should have 3 Aura Air units installed.


In addition to meeting Delos’ performance evaluation standards, Aura Air’s compact dimensions and weight, low energy consumption, and simple maintenance make it ideal for installation in small spaces such as buses.


Aura Air successfully raised indoor air quality in Delos’ buses, with a 75% decrease in VOC levels, a 12.2% improvement in PM 10 levels, a 12% reduction in PM 2.5 parameters, and a 54% improvement in AQI.


According to laboratory test results, Aura Air can deliver 200.7 cubic meters of filtered clean air per hour (based on the removal of dust, which has a particle size of 0.5-3 microns).


Based on Aura Air’s clean air delivery rate (CADR) in an ideal, closed environment, Delos recommends installing 3 Aura Air units on each CDC bus. This would allow the air to be filtered about 6 times per hour.

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