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The news  that India’s capital city, Delhi, had put a temporary halt on construction (and other industrial activity) and closed schools may have escaped your notice amid our own pandemic lock down concerns and the general run up to Christmas 2021.
Why did the Indian Government do that? Essentially to curb the rise in pollution due to a toxic cocktail of fugitive particulates, traffic fumes and coal-fired power station emissions which together can cause premature deaths amongst the young and elderly who are susceptible to acute respiratory failure. But there is also the risk of chronic cancers amongst the wider population.
A similar ‘construction dust’ problem had existed in China’s capital Beijing in 2008 as reported by the Xinhau News Agency, which resulted in suspension of all earthwork construction projects on windy days. The Deputy Head of the Beijing Municipal Environmental Protection Bureau (BMEPB) commented that “particles and dust at construction sites, which cover 100 million square meters in Beijing, are a major source of pollution”. Significant when you remember that Beijing was about to host the Olympics!
Fast forward to 2015 and China daily reported that Beijing had begun to levy construction dust pollution fees. “Dust accounts for approximately 14% of PM2.5 (fine particle) pollution in Beijing” according to the BMEPB. It was estimated that a construction site produced an average of 0.26kg of dust per square meter every month. That would have equated to 26 million tonnes back in 2008 which is equivalent to a staggering 185 Blue Whales……per month!
Meanwhile in the UK, the 2019 Lord Mayor’s report  had similarly stated that 15% of the London’s particulates were from construction.
The common denominator here is a combination of high population density, the sheer intensity of construction and demolition activity, which is synonymous with dust, but there are other emissions including noise, ground borne vibration, diesel particulates and nitrogen oxides (NOX) from plant and machinery. And the problem can only get worse as people inexorably move to the major cities.
According to the Grayline Group , the data is eye-opening. They stated that the United Nations in 2009 and the International Organization for Migration in 2015 both estimated that around 3 million people were moving to cities every week and that approximately 54% of people worldwide now live in cities, up from 30% in 1950. Sources estimate that this will grow to two third’s of world population in the next 15-30 years with more than half of urban dwellers living in 1,022 cities with greater than 500,000 inhabitants. There are currently 29 megacities with populations of over 10 million, up from 2 in 1950 which was projected to grow to between 41 and 53 by 2030. Additionally, there are 468 cities with a population of over 1 million, up from 83 in 1950.
Grayline went on to say that a Yale research group projected that urban land coverage would expand by 463,000 square miles by 2030 to cover just under 10% of the planet’s land, equivalent to 20,000 football fields being paved over every day. Amongst the so-called sensitive receptors there are schools and hospitals, while in the case of London, for example, there are historic buildings and many high net-worth residents and Corporate HQs to consider. According to a December 2021 article , a morning walk around the capital quickly reveals the tower crane business is picking up, again welcome news after the serious recession that followed the boom in the 1980s. One man’s meat is of course quite literally someone else’s poison.
What is PM2.5 and what are the dangers?
PM2.5 refers to atmospheric particulate matter (PM) that have a diameter of less than 2.5 micrometers, which is about 3% the diameter of a human hair. Commonly written as PM2.5, particles in this category are so small that they can only be seen with a microscope. They are even smaller than their counterparts PM10, which are particles that are 10 micrometres or less, and are also called fine particles.
Fine particles can come from various sources. They include power plants, motor vehicles, airplanes, residential wood burning, forest fires, agricultural burning, volcanic eruptions, dust storms (we have all seen Sahara dust deposited on our cars) and of course from construction. The latter includes silicates and particles from diesel powered plant. Some are emitted directly into the air, while others are formed when gases and particles interact with one another in the atmosphere. Sunlight also reacts with NOX to produce ozone which ironically in the upper atmosphere protects us from harmful rays while at ground level they become poisonous.
Since they are so small and light, fine particles tend to stay longer in the air than heavier particles. This increases the chances of humans and animals inhaling them into the bodies. Owing to their minute size, particles smaller than 2.5 micrometers are able to bypass the nose and throat and penetrate deep into the lungs and some may even enter the circulatory system. Studies have found a close link between exposure to fine particles and premature death from heart and lung disease. Fine particles are also known to trigger or worsen chronic disease such as asthma, heart attack, bronchitis and other respiratory problems.
What are the effects of too much noise?
Noise exposure can cause two kinds of health effects: both auditory and non-auditory. Auditory effects include hearing impairment (also known as noise induced hearing loss) resulting from excessive noise exposure due repeated exposure to levels above 85 dBA or more, typically found in many industrial activities including construction.
Non-auditory effects include stress, related physiological and behavioural effects, and safety concerns at substantially lower levels unlikely to cause NIHL. Besides well-established risk factors, such as cardiovascular diseases and unhealthy lifestyle, environmental exposures may also play a role in the development of dementia. A recent study  has shown a link between transportation noise and dementia and worldwide, the number of people with dementia is expected to exceed 130 million by 2050, making it a costly and growing global health crisis.
Perhaps more typical of construction are sudden impulse noises, for example from piling, which are typically perceived as more bothersome than continuous noise from traffic of equal volume. Annoyance effects of noise are minimally affected by demographics, but fear of the noise source and sensitivity to noise both strongly affect the 'annoyance' of a noise. Sound levels as low as 40 dBA can generate noise complaints depending on the background levels and the lower threshold for noise producing sleep disturbance is 45 dBA or lower.
What are the effects of vibration?
Vibration from construction activity can be transmitted to adjacent structures in densely populated areas, which can cause structural damage and at worst collapse! Three primary activities relate to most, if not all, of the vibration-related damage claims in construction, include:
- Site clearing and removal
- Site grading and soil compaction
- Installation of deep foundations
Historic building and structures, data centres and hospitals are at risk, the latter two due to the presence of sensitive electronics. MRI scanners are a particular example of where strict vibration limits must be observed.
Legislation and Best Practice
The City of Westminster’s Code of Construction Practice, 2022 (the Code), probably represents the most up to date benchmark in the UK. It states that “Our City is the heart of the capital, serving up to 1 million residents, workers and visitors every day. It is densely populated with premises and developments of all kinds including housing, businesses, historical and cultural sites - and as the City reopens following the Covid19 pandemic new developments and construction will continue to play a vital role in promoting our City as well as supporting our wider environmental ambitions including meeting the challenge of the Climate Emergency. However, construction can also cause significant disturbance to local residents, businesses and traffic, and how we manage and balance these pressures has an impact on the daily lives of people, the economy and the environment.”
It calls upon various sources of legislation from the Control of Pollution Act 1974 (COPA), the Environmental Pollution Act 1990 and the requirements of the Environment Act 2021, which requires targets to be established for PM2.5.
Monitoring for noise, dust and vibration on an individual case-by case basis is mandated by the Code and developers are advised to obtain so-called prior agreement under Section 61 of COPA before starting work.
For those without a ‘Section 61’ they will be issued with a Section 60 Notice prior to works commencing onsite which sets the site working hours and ensures that best practice working methods to control noise and vibration are maintained on site.
Delays to projects caused by breaches of the Code and/or limits can cost many tens of thousands along with immeasurable reputational damage!
Modern systems like the Casella Guardian promoted by Wates Construction  meet the ‘multi agent’ monitoring requirements by pushing data to the cloud for easy report access whilst providing text and/or email alerts of breaches which allow for early intervention.
The inexorable population shift to cities requiring more and more land development for housing, retail and businesses has the potential to cause environmental emissions, which at best can disturb quality of life and at worst prove fatal. To comply with legislation and limits which might otherwise result in fines and costly project delays, it is advisable (and in some cases mandatory) to deploy multi-agent monitoring systems that can provide reports to prove compliance and importantly provide alerts to trigger appropriate interventions.
6. Wates Construction, SHEQ Best Practice & Innovation, BP/2020