He then puts on head-to-toe safety gear, straps the pack to his back and methodically sprays the walls, windows and corners of the room.
Owusu's visit to Domeabra, a small community in the Obuasi area of the Ashanti region in central Ghana, is his latest stop in the country's fight against malaria.
The death of two of his friends from the disease spurs him on. "Why wouldn't I help if others are dying? I am here today helping to eradicate this deadly malaria," he told AFP.
Malaria, which is spread to people through the bites of infected female mosquitoes, is one of the world's deadliest diseases.
According to the World Health Organization, there were 216 million cases of malaria in 91 countries across the world in 2016 and 445,000 deaths.
Most of those cases and deaths -- about 90 percent -- were in sub-Saharan Africa.
In Ghana, which is home to some 28 million people, there were 4.8 million cases and 599 deaths last year, a marked drop from the 2,200 who died in 2011.
But with global concern that the fight against malaria has reached a plateau, African governments and development agencies are looking at new ways to step up the fight.
That includes preventative measures such as distribution of insecticide-treated mosquito nets and developing a vaccine against the disease but also indoor spraying.
Ghana is the first on the continent to introduce the large-scale use of a new "third generation insecticide" against mosquitoes, which have developed a resistance to other chemicals.
As Ghana's rainy season approaches, when malaria cases increase, Owusu and his colleagues at the non-profit organisation AGALMal are working flat out.
The organisation grew out of a social initiative by global mining firm AngloGold Ashanti and has a laboratory in the grounds of an old mining site in Obuasi.
There, tiny mosquito pupae dart around in water in a white plastic container in a lab.
Soon they will transform into mosquitoes and be studied by scientists. Technologist Paul Osei-Bonsu said chemical resistance was a major issue for the spraying programme.
If a population of mosquitoes is sprayed and just one survives and reproduces, the resistance will be passed on, he explained.
"If you use the same spray over time you will have 90 percent of the population not dying," he added.
Programme director Samuel Asiedu says mosquitoes are "intelligent insects", so the new chemical -- SumiShield 50WG -- should be more effective when rotated with others.
In 2006, after the first two years of the indoor spraying, the hospital in Obuasi saw a 75-percent decrease in malaria cases.
That led to the programme being expanded with additional support from global health initiative Unitaid and the Global Fund partnership.
Currently, the indoor spraying programme targets the homes of 1.2 million people.
"We are anticipating other chemicals to come on board by the end of the year so we can be rotating the use of chemicals to prevent resistance development," said Asiedu.
Unitaid project director David McGuire said he hoped the scheme "will convince donors and national governments to increase their investment in this life-saving intervention".
'Peace of mind'
Keziah Malm, who manages the national malaria control programme at the Ghana Health Service, says the new WHO-approved spray is considered safe and has been tested internationally and locally.
It will be used in Obuasi and Ghana's far north -- all of the Upper West region and three districts in the Upper East -- which are high-risk zones for malaria.
Local communities still need to be convinced about the benefits of having their homes sprayed. But Asiedu says only a handful of people refuse.
Sprayers themselves also speak to households about the work and the risks to health from the disease, which can lead to severe illness and death if not treated within 24 hours.
"If I go to the whole house and someone does not want it I have to sit the person and let them know the importance of the spraying because malaria kills," said Owusu.
"It's very important we all understand that malaria is a killer. We have to eradicate it and kick it out of Obuasi and the nation as a whole."
During the course of his work, he's found everyone has a story about the disease.
"I sprayed a full house and the owner was telling me her son died some years go from malaria. He would be 18 years today. She was crying bitterly," he added.
Children under five and pregnant women are considered most vulnerable to malaria.
Seamstress Victoria Awuah lives in an eight-room house some 30 minutes from the lab.
She is seven months pregnant and doesn't need much persuasion to have her room sprayed.
"The spraying really helps. It helps us so that we don't get sick, give us peace of mind and rid this area of all these insects," she added.