As the COVID-19 pandemic continues to accelerate with over three million cases around the world, countries are taking drastic measures in order to control the further spread of the infection including spraying streets with disinfectants.
Recently, a number of photos of workers wearing protective gear and spraying the streets of cities with disinfectants have become popular on social media. More and more countries have been noted to follow the same steps.
For instance, Spain was amongst the first countries to not only follow but also take the controversial measure of spraying its beaches with bleach. Where such efforts by the governments are applauded by some, others have questioned the effectiveness of spraying streets and other public spaces.
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In accordance with scientific data, the effectiveness of spraying disinfectants is dependent on a number of factors including how a particular disinfectant works, how the targeted virus transmits the specific conditions in which the sprays are used.
The infection caused by the novel coronavirus has been noted to spread mainly in two ways. The first one is by aerosols and airborne particles that come from a person who has tested positive for COVID-19. Usually, these particles expel into the air through coughing or sneezing.
This is why health care workers are required to wear specialized masks that can keep the smallest particles away and cut down the risk of contracting the virus. However, the aerosol particles are usually larger and do not stay in the air for a long time.
Read more on recommended disinfectants for COVID-19 here.
Nearly all of the droplets that are expelled into the air later settle on the area near the patient or surfaces nearby. Surfaces are the second way the virus can transmit and infect another person.
One study conducted on how long COVID-19 can thrive on surfaces concluded that the virus can last for up to seventy-two hours but the material and nature of the ground or surface they land on may cut down this time period.
People who come into direct contact with these infected surfaces can easily contract the virus and get an infection.
Therefore, health authorities including the Centre for Disease Control and Prevention, have urged people to use disinfectants on surfaces. Till now, the best disinfectant to use for preventing the novel coronavirus is diluted bleach.
However, it should be noted that the research that shows the use of diluted bleach is effective for COVID-19 also reports that a contact time of one to five minutes is fundamental.
Using bleach outdoors can be problematic in a number of ways even if it is sprayed on every possible surface in the streets of a city. In outdoor conditions, factors including sunlight come into play. Many times, the bleach would become ineffective before the COVID-19 virus is killed.
In addition, the virus can only transmit from the ground to a person if a person touches the ground and then his face. Most people are not likely to touch their face after touching the ground without washing hands.
Therefore, another reason why spraying streets does not make a significant difference is people are rarely going to contract the infection via coming into contact with the ground or even the pedestrian footpath.
In comparison, road crossing buttons and railings can be bigger sources of the infection but would require cleaning prior to being sanitized as dirt can make disinfectants ineffective.
Lastly, spraying disinfectant or bleach into the air can have effects for a limited amount of time but this step would be more harmful than useful as it may damage the respiratory system. Spraying the streets with disinfectants may, therefore, be not very useful in general.