In India, construction projects are geared towards creating commercial, residential, industrial, or infrastructure-related developments. In recent times, the construction sector has grown due to the synergistic impacts of government efforts (e.g., the Pradhan Mantri Awas Yojana – Urban, 2015) and increasing urbanisation.

For the period 2024-2028, with a CAGR of 9.8 per cent, the construction industry output in India has been estimated to reach INR 36.58 trillion by 2028. Currently, it contributes around 8 per cent to the national GDP and employs more than 40 million people (India Construction Industry Report 2024) . The sector is experiencing the growth in both residential and commercial segments due to government policies, rising demand, and the adoption of advanced technologies. Moreover, initiatives led by the Finance Ministry are expected to generate employment in urban and rural areas, further driving economic development.

However, the exponential growth in this sector might have led it to become one of the primary contributors to air pollution. City-specific source apportionment studies indicate that the re-suspension of dust from large, medium, and small construction sites degrades air quality (AQ) at the local and regional level. For instance, in cities such as Delhi, Amritsar, and Chandigarh, the resuspension of dust accounts for around 18–20 per cent of fine particle matter (PM2.5 – particulate matter with a diameter ≤2.5 micrometres) (Guttikunda, Nishadh, and Jawahar 2019).

This explains why this sector is frequently blamed during poor AQ episodes. For instance, in Delhi, construction activities were restricted for nearly 53 days in 2022 and 20 days in 2023 (Confederation of Indian Industry 2023) as an emergency response to decrease the air pollution burden on citizens. However, these bans caused financial stress to customers, contractors, and labourers. A one-month suspension of construction activities might result in a delay of three to four months in a project’s timeline (Kumar n.d.). Additionally, to recover the losses suffered during this period, builders pass down the burden to customers. However, the effectiveness of such bans in improving AQ has not been established.

While policymakers and regulators have put in place several restrictive measures to limit the detrimental effects of construction activities on the overall AQ of the region, there have been frequent instances of noncompliance – due to a lack of awareness, difficulties in changing behaviours, and financial factors. Noncompliance on sites continues to significantly impact AQ, the environment, and the health of people in the vicinity.

Studies have proven that a strong regulatory architecture with an efficient monitoring and compliance mechanism (Kanchan 2022; Zutshi and Creed 2015, Commodore et al., 2017), behavioural changes (Shepherd et al., 2010), and technological improvements (Larkin and Hystad, 2017; Zuo et al. 2024) can reduce the air pollution impact of construction activities.

Regulations for managing the environmental impacts of construction activities

In India, the legislative framework to regulate construction work is diverse, with different sets of laws, rules, and regulations. Within this gamut, environmental regulations governing construction and demolition (C&D) activities can be broadly classified into two categories: (1) those to be followed before the commencement of any construction activity and (2) those to be complied with during any construction process.

I. Laws that mandate that different types of environmental clearances (ECs) must be secured before engaging in any construction activity: These laws specify the environmental criteria that building projects should meet before the construction work starts. These primarily include the Environmental Impact Assessment (EIA) Notification, 2006, and its subsequent amendments issued under the Environment Protection Act, 1986 (Parivesh n.d.a). The 2006 notification classified construction projects into two categories, A and B.1 Projects falling under Category A are required to hold public consultations to discern the potential environmental impact of the project. These projects are further categorised

as per an amendment passed in 2014 based on their valuation, the project site, the ecological sensitivity of its surroundings, and so on. As a result, a handful of building projects, such as schools and hostels, are not required to obtain ECs as long as they have received authorisation under waste management rules and have certain systems, such as rainwater harvesting, in place.

Within Category B, projects are further divided into B1 and B2 by state-level expert appraisal committees. B1 projects are required to provide an EIA report, while B2 projects do not need one. Unlike B2 projects, most Category A and B1 projects involve public consultations. In general, Category A projects face stringent scrutiny, while Category B projects enjoy a more relaxed clearance process.

Construction activities around coastal areas are also required to obtain clearances under the Coastal Regulation Zone (CRZ) notifications. 2 As per these notifications, which are released from time to time, projects are divided into four categories depending on the ecosystem’s sensitivity, the population, and infrastructural density. Coastal zone management authorities (CZMAs) have been constituted for different coastal regions under these regulations and are responsible for preparing coastal zone management plans (CZMPs). Construction project proponents are required to comply with these CZMPs.

II. Laws regulating ongoing construction activities: These laws direct how construction activities should be carried out on the sites and include the following:

a. The National Building Code, 2016, provides a set of guidelines and standards that construction agencies have to follow in the design, construction, and maintenance of buildings in India.

b. The 2018 amendments to the Environment Protection Act, 1986, mandate the implementation of dust mitigation practices during C&D activities. Some of these measures are as follows:

• No excavation of soil should be done without an adequate dust mitigation protocol.
• No loose soil, sand, or C&D waste should be left uncovered.
• A windbreaker system should be provided.
• A water-sprinkling system should be put in place.
• Grinding and cutting of building materials in open areas are prohibited.
• Roadside storage of construction materials and waste is prohibited.
• Vehicles plying construction material and waste should be kept covered.
• Provisions should be made for dust monitoring, suppression, and management at the construction site. Developers are mandated to measure PM2.5/ PM10 levels and monitor the effectiveness of dust control measures. These rules, however, are only applicable to those cities/towns that have failed to meet the PM10/PM2.5 limits prescribed by the National Ambient Air Quality Standards (NAAQS).

c. The Construction and Demolition Waste Management (C&D WM) Rules, 2016, and Solid Wastes Management Rules, 2016, also specify how C&D and solid waste are to be managed by project developers on site.

• These rules prescribe separate sets of duties for various actors in the construction and pollution control ecosystem – waste generators, service providers and contractors, the state government, local authorities, and so on.
• The rules make it mandatory for C&D waste generators to prepare a plan that delineates the strategies they will adopt to reduce, reuse, and recycle the C&D waste produced at the site.
• Construction companies must implement measures to minimise dust emissions and other air pollutants during C&D activities. These include the following:
  • Construction sites must be covered with sheets to reduce dust flow.
  • Fine particles (up to 2 millimetres) generated from processed C&D waste must be used for covering fresh waste daily.
• Construction materials must be promptly removed from the site once their utility is over, and exposure to wind must be mitigated.
• Construction firms generating more than 20 tons of waste a day or 300 tons per project in a month must mandatorily pay for the processing and disposal of all C&D waste generated by them, apart from also paying for its storage, collection, and transportation.
• Construction companies must also develop a waste management plan that includes measures to prevent dust emission, monitor AQ, and ensure compliance with AQ standards. To that end, construction sites must effectively deploy AQ monitors to capture real-time data on emissions.

In addition, the Solid Waste Management Rules, 2016, stipulate mandates for collecting, storing, transporting, processing, and disposing of C&D waste. The following are some of the ways in which the rules are helpful:

• Segregation of waste: The rules require that C&D waste be segregated at source into recyclable and non-recyclable materials. This helps to reduce the amount of waste that needs to be disposed of and increases the amount of waste that can be recycled.
• Handling and transportation: The rules specify safe and environmentally responsible procedures for handling and transporting C&D waste.
• Disposal: The rules mandate certain conditions for the disposal of C&D waste, including the use of approved landfill sites and the requirement for waste to be treated before disposal. The Central Pollution Control Board (CPCB) will publish guidelines for maintaining buffer zones, prohibiting residential, commercial, or other construction activity beyond the outer boundary of the waste processing and disposal site, for different sizes of facilities handling more than 5 tons per day of solid waste.
• Responsibility of producers: The rules place the responsibility for managing C&D waste on the producers of the waste, including construction companies and demolition contractors. This helps to ensure that waste is managed correctly and disposed of properly.

Key provisions from the regulations discussed in this section are listed in Annexure A.

The compliance monitoring regime

To realise the full potential of regulations, the regulatory framework should be complemented by a robust compliance monitoring regime. In the context of construction pollution management, we find that the compliance monitoring mechanism is well-defined, but it has gaps, which are highlighted later in this section.

In accordance with the Environment (Protection) Amendment Act, 2018, construction companies are required to maintain PM2.5 and PM10 levels at construction sites that align with the NAAQS. The Commission for Air Quality Management in National Capital Region and Adjoining Areas (CAQM), which was constituted to protect and improve AQ in the NCR and adjoining areas, has issued from time to time a host of statutory directions and advisories to regulate construction dust emissions, besides calling for compliance with various statutes, namely the Construction and Demolition Waste Management Rules and related CPCB guidelines. CAQM has an extensive monitoring mechanism for ensuring the compliance of the industry with dust mitigation practices. Flying squads and inspection teams constituted by the CAQM carry out inspections of C&D project sites, in addition to the inspections conducted by the respective state pollution control boards (SPCBs).

Under the statutory directions of the CAQM, to facilitate remote monitoring of larger C&D projects, all projects in the NCR on plot areas ≥500 square metres are required to register on the respective dedicated web portals in the states of Haryana and Rajasthan and the National Capital Territory (NCT) of Delhi and certify their compliance with various stipulated measures. The project sites also have to be video-fenced to enable.

remote monitoring by inspection agencies through web portals. Such web portals are functional in the NCT and Haryana and are under development in Rajasthan.

The CAQM has further suggested the following measures to ensure compliance with their dust mitigation directives:

• Cross-verification of the parameters certified by the construction company on the portal vis-à-vis ground conditions at the site.
• Installation of windbreakers, dust screens, watersprinkling systems, dust suppressants, and soil stabilisation equipment in construction facilities.
• Deployment of adequate numbers of anti-smog guns in proportion to the area of the construction site:
  • At least one for a total construction area of 5,000– 10,000 square metres
  • At least two for a total construction area of 10,001– 15,000 square metres
  • At least three for a total construction area of 15,001–20,000 square metres
  • At least four for a total construction area of 20,000 square metres.
• Covering C&D materials with potential for dust emission.
• Using a checklist based on the guidelines notified for dust control to monitor compliance online.
• Conducting self-audits on a fortnightly basis by construction firms and a self-declaration to that effect uploaded on the web portal.
• Installation of Low-cost sensors to estimate PM concentrations at construction sites, linked to a cloud platform that displays the concentration data on a live dashboard on the online portal.

Deployment of AQ monitors and video fencing at large construction sites certainly strengthens the environmental compliance monitoring regime, but how the data obtained through such monitoring can be used to regulate activities on site needs further examination.

We conducted a review of regulations and guidelines from other countries, and consulted with international experts in the field, to explore the matter further. This helped in identifying several gaps that need to be addressed to strengthen the compliance regime further

Are the data reported by construction sites credible and comparable?

As highlighted earlier, large construction sites are required to monitor and report AQ levels. However, it is important to note that in the absence of guidance on standardisation processes, the measurements from any two sites will not be comparable. The number and locations of monitors at the site can be standardised as well as the certification requirements for the monitoring equipment used.

For instance, in the United Kingdom, the Environment Agency has established the Monitoring Certification Scheme (MCERTS), which provides comprehensive guidelines on the standards that AQ vendors must adhere to when monitoring emissions that impact the environment. MCERTS encompasses various forms of ambient monitoring equipment, including low-cost AQ sensor systems. Notably, MCERTS mandates rigorous testing of PM measurement instruments, with an extensive focus on data precision and reliability.

India’s central regulatory authority has cautioned against the use of data generated by low-cost monitoring equipment for calculation and public dissemination of the Air Quality Index. But the CPCB has also indicated that SPCBs could use these devices for qualitative assessments of dust generated at building sites. For such assessments, however, standardisation and intercomparability of data should be critical considerations.

What is being compared in terms of data from the construction sites?

The absence of thresholds with respect to the increase in air pollutant levels at building sites leads to challenges in the evaluation and enhancement of regulatory compliance. It is imperative to underscore that welldefined thresholds of exceedance can serve as a benchmark against which the localised AQ impacts of a construction site can be assessed.

For instance, in the United Kingdom, a threshold has been instituted (viz., ~200 micrograms per cubic metre of air), and if this is crossed, the construction site is deemed to impact local AQ. This particular threshold assumes importance as it offers real-time feedback to site operators, thereby enabling them to take remedial measures to control pollutants.

In China, the Environmental Protection Law (2015) regulates construction activity by establishing pollutant emission standards for construction equipment and environmental monitoring. The Environmental Impact Assessment Act, 2003, mandates the environmental impact assessment of construction schedules and projects, identifies their effects, allocates legal liability, and supplementary provisions. The Environmental Protection Bureau has suspended the examination and approval of environmental impact assessment documents of construction projects that are likely to increase the total emissions of key air pollutants in the region.

A threshold for construction sites in India is yet to be established. Without such a threshold, classifying a building site as polluting and clamping down on its activities would be an entirely subjective decision. On the flip side, having such a threshold would help regulatory authorities in isolating polluting sites and roll out targeted directions towards banning their operations.

Who is looking at the data, and for what purpose?

In India, as the regulatory framework for monitoring environmental compliance on construction sites continues to develop, the ongoing monitoring activities being conducted at these sites hold the potential to significantly contribute to the establishment of standardised criteria for determining acceptable limits of environmental exceedance.

The localised impacts of construction activities will vary from site to site, and the data generated from different construction sites can be collected and used to set thresholds for sites falling within different size categories. Once thresholds are in place, local authorities can then use the data to issue alerts to building sites and order a roll-out of tailored preventive measures.

Furthermore, with the data collected, local authorities could assess the effectiveness of the various pollution control measures being implemented on the site and use this information to guide other construction sites on suitable control protocols. For instance, the Seoul Metropolitan Government established installation standards for facilities and measures to control fugitive dust. South Korea’s Construction Machinery Management Act prescribes specific machinery that should be used for construction – similar to the Clean Air Act in the USA (UNDP 2016). While the recent CAQM guidelines provide technological recommendations such as the use of smog guns on construction sites, it does not provide any guidance on the type and emission standards of machinery that is suitable for use for construction activity.

While examining the compliance monitoring mechanisms for construction dust management in India, it becomes evident that the effectiveness of these measures hinges on the deployment of monitors at construction sites. Given the transient nature of construction activities, it is imperative to not only establish monitoring systems but also ensure their ongoing compliance with prescribed methods. Drawing insights from international experiences can shed light on best practices in designing a robust monitoring framework.

Behavioural nudges

In their efforts to improve outcomes for citizens, governments and a number of private organisations have started relying on a more human-centred strategy in recent years. Identifying contextual and environmental elements and utilising them as the basis for solutions is a crucial component of a behavioural approach (Behaviour Insights Team 2022).

In the second part of the current study we aim to address the challenge of improving compliance with targeted clean construction practices by using a ‘softer’, behavioural approach. This entails leveraging behavioural insights to understand how PM emissions resulting from construction activity can be reduced. These insights highlight contextual psychological, environmental, and logistical barriers and facilitators that influence behaviours. This strategy helps researchers analyse people’s actual behaviour rather than just what they claim to be doing and design tailored programmes.

Adopting a behavioural approach helps researchers explore the psychological drivers of clean construction behaviours associated with specific construction activities in unique contexts. Previous research has shown that despite the availability of physical resources, psychological biases impede the adoption of environmentally sound construction practices. For instance, Noh et al., 2018 found that specific measures such as wheel washing, dampening loose soil, and covering materials with tarpaulin sheets can control the release of airborne dust due to vehicle movement during construction. Yet, a number of obstacles, such as a perceived scarcity of time, competing priorities, or certain features of the site layout can prevent the widespread adoption of these practices.

While behaviour control is a widely used strategy to reduce dust emission, workers’ behaviour in relation to dust mitigation has not received much attention in previous research (Kaluarachchi et al., 2021). For instance, workers may be aware of safety equipment such as goggles, gloves, and a protective face mask to reduce their exposure to PM. But whether they adopt such measures depends on factors such as personal knowledge, incentives, prevailing social norms, and other environmental issues.

So far, however, the emphasis has been on finding structural and engineering solutions, with little focus on worker behaviour. The study by Kaluarachchi et al., 2021 shows assigning of responsibilities and awareness of repercussions can positively affect personal norms and, in turn, worker behaviour. They recommend that builders launch programmes that reveal the environmental impacts of pollutants in efforts to change people’s personal norms and encourage pro-social and environmentally responsible behaviours. One of the obstacles to taking action is a lack of knowledge about the negative effects the status quo has on the environment and human health.

As shown in the study by Nij et al. (2003) on dust pollution management, younger construction workers used pollution control measures somewhat more frequently, particularly when it came to protecting the respiratory system. This observed behaviour was connected with workers being aware of the health risks associated with dust inhalation. Since the body of knowledge is always expanding, it’s possible that younger employees are trained to recognise these health issues. The older population, in contrast, might not be as conscious of the problem or might view it differently. Through observations and focus group discussions with construction workers, we have uncovered crucial behavioural insights pertaining to the three components of the Capability, Opportunity, and Motivation – Behaviour Framework (Michie[et al. 2011). These insights serve as the basis for developing individualised, doable, and culturally appropriate interventions.

Even after years of awareness campaigns and laws in support of air pollution mitigation, we find that most people are still unaware of the harmful effects of dust particles in their workplace and the mitigation measures that need to be undertaken. The lack of AQ monitoring data is a major factor contributing to inaction. Furthermore, a number of behavioural influences, including goal setting, physical enablers like money and resources, and contextual motivators affect choices and behaviours. It has been demonstrated that theory-based educational interventions are successful in changing behaviours in a variety of health-related areas (Shoesmith et al. 2022; Willmott et al. 2021).

In this study we use relevant behavioural change frameworks to analyse the factors impacting the uptake of ‘clean construction’ behaviours and pilot tailored interventions for various target groups at active construction sites. Our preliminary behavioural assessment suggests that workers are generally unaware of the risks associated with PM exposure and are not very motivated to take proactive steps. The gap begins with the absence of reliable data. This study created an engagement platform to close the awareness and knowledge gaps among contracted and on-site workers and promoted specific high-impact clean construction behaviours. Some of the most relevant behaviour change techniques were utilised to design the interventions. They are described as part of the Behaviour Change Wheel process by Michie, Atkins, and West (2014). They include stressing the negative consequences of air pollution on health and the environment, describing the health effects, providing training, and other intervention techniques.

This issue brief serves as an introduction to our multipart series on the control and mitigation of pollution resulting from building projects. In the next releases, we will explore possible on-site behavioural approaches and do a thorough cost–benefit analysis of these interventions. In this paper, the discussion is confined to improving the AQ-monitoring protocols used at building sites.

Designing a monitoring network for a construction site requires careful planning and review of the site plan, the construction plan, and land use information of the surroundings. To understand the existing approaches to monitoring AQ at the building site, we carried out a systematic review of articles published between 2015 and 2022 by searching for keywords including ‘monitoring strategy’, ‘monitoring network’, ‘air pollution and health impacts of constructions’, ‘exposure estimation of construction labourers’, ‘pollutant concentrations during different construction activities’, and ‘construction-related air pollution’ in databases such as PubMed, Scopus, and Google Scholar.

Table 1 summarises the approaches identified from the review and it suggests that regulation of construction activities using data from real-time monitoring stations is relatively unexplored in the scientific literature. There are also some other studies (Cao et al., 2016; Luo et al., 2021, Kalavakonda et al., 2021; Moraes et al., 2016) that estimate the pollution levels at the construction site by measuring the emissions of different types of heavy equipment, using instrument-specific emission factors or using information on the fuels used by different construction equipment.

While the studies listed in Table 1 identified and executed various methodologies for monitoring AQ at construction sites, none of them proposed a network design for regulating activities at the construction site. For example, the deployment of any active or passive AQ monitor should always be accompanied by real-time data transfer and/or cloud storage to analyse emission patterns. Alternatively, quantifying emissions using emission factors ignores the impacts of meteorology and other local or regional sources of pollutants. As a result, there is very little room to apportion the impacts of nearby sources. Further, the idea of installing monitors to estimate exposure to air pollutants has frequently been criticised (Azami et al., 2014; Milivojevi� et al., 2023) for its lack of representativeness in terms of study design and sample size estimation.

In the subsequent sections of this study, we utilise this understanding to develop ways in which AQ monitoring can be used to regulate construction activities on site, thereby reducing the environmental footprint of this sector. Furthermore, this approach also considers capturing the impact of all construction activities at the site, thus allowing for the isolation of pollutantintensive activities.

Source: Authors' analysis

Key considerations

Designing an ambient AQ-monitoring network is pivotal to controlling pollution from construction activities. This requires the consideration of contextual data related to emission sources and pollutant categories, historical AQ levels, demographic and health statistics, topographical influences, local disturbances, meteorological influences, site accessibility analysis, and the designated monitoring timeline. Determining the optimal number of monitoring stations and their strategic placement hinge upon a multifaceted set of variables – including topographical features, local meteorological patterns (wind direction, speed, mixing height, and temperature), the distribution and magnitude of pollution sources (industrial facilities and vehicular emissions), pollutant concentrations, population density – as well as the overarching objectives of the AQ-monitoring initiative and available resources.

Our comprehensive assessment underscores the need to consider of the following key factors while setting up a monitoring network at the construction site:

• Nature of the construction work: The effectiveness of deployment strategies and the requisite sensor quantity for monitoring air pollutant concentrations significantly depend upon the specific characteristics of the construction work. (Azami et al. 2014). For example, constructing or maintaining a road entails distinct parameters compared with erecting a residential building, encompassing varying emission profiles and site dimensions and necessitating tailored monitoring approaches.
• Surrounding land use: Diverse land use areas such as residential, commercial, and mixed use carry varying potential exposure risks associated with construction activities. Notably, construction work in residential areas entails higher exposure risks than that in commercial areas owing to the higher population density in the former. Furthermore, construction work in commercial areas or densely populated areas like marketplaces, business hubs etc. in cities poses significant exposure risks to the population in the surrounding areas based on the time of day and land use. Hence, air pollution monitoring at these sites requires different strategies(Hong et al. 2021; Kang et al. 2021).
• Meteorological factors: Construction activities contribute to air pollution largely through dust resuspension, where local meteorological conditions – including wind speed, wind direction, and frequency of rainfall – as well as soil characteristics (silt factor) play a role. Therefore, it is crucial to incorporate meteorological data for ensuring data quality and facilitating related analysis (Li et al. 2019).
• Geographical and topographical factors: The topography of a construction site can significantly influence the wind direction, speed, and flow, which ultimately impact the AQ of the area. For instance, a hillock may act as a barrier to wind direction and speed and may alter the flow before and after the barrier. Similarly, a forest cover patch may help in settling dust and prevent further movement. Consequently, the planning of an AQ-monitoring network necessitates careful consideration of these geographical aspects.
• Population density and sensitive areas in the vicinity: Areas with high population density surrounding a construction project and the proximate sensitive areas bear a heightened potential for adverse impact and potential conflicts. As a result, it is imperative to develop stringent monitoring plans and protocols tailored to these high-impact areas.
• Pollutants to monitor: Construction processes produce dust characterised by a wide range of sizes and material types. The larger particles, called ‘dust’, tend to settle quickly and are mostly a health hazard only to operators in the immediate vicinity. The smaller particles (PM10) are usually invisible and may not seem to be an obvious hazard (Faber et al. 2015) . However, they can be carried much farther in the air and are potentially a health hazard to both workers on the site and people living and working outside the site boundary in the local neighbourhood.
• Suitable monitoring technology: Several monitoring technologies are available in the market; however, the quality and data accuracy of most of these monitors are still being explored or improved (Budde et al., 2018; Castell et al., 2017; Chojer et al., 2022; Chojer et al., 2020). It is, therefore, important to evaluate the performance of the technology chosen for installation and ensure its regular calibration and maintenance.

However, there may be concerns about maximising the uptime of these monitors while deployed at the site which is essentially a function of airflow near the inlet, equipment design, inference from humidity, or secondary PM for optical instruments (IAQM 2018). The instrument should be supported by regular servicing (as recommended by the manufacturer), cleaning and calibration, and frequent data download to ensure that it is working properly (Kang et al. 2022). Furthermore, trained resources should be available at the site for additional maintenance of the device, including electrical or mechanical work.

Steps for building a monitoring framework

The following steps should be followed for establishing a monitoring network: 

• Understanding the layout of the site: Deploying monitors requires a comprehensive understanding of the site layout to predict the types of construction activities that will be carried out during the overall project timeline. This would help in designing a monitoring network for the site. The specific location of the monitors can be finalised during primary site visits in consultation with site supervisors. The monitor locations should be such that they do not interfere with the movement of equipment, material, and human resources.
• Selection of monitors: Different sensors can be considered, but they should be compared with a reference monitor and calibrated for a larger range so that the network is able to consider the difference between activities and thus estimate the impact. Monitoring particles of different sizes can be costly and complicated if reference-grade monitors are used. Modern-day devices such as sensors and wireless sensor networks can reduce friction when monitoring the concentration of differentsized particles. Currently, the deployment of AQmonitoring stations is limited due to their large size, high cost, and high power requirement.
• Selection of a weather station and deployment: As the AQ data should be supported with meteorological data, an automated weather station (AWS) should also be deployed at the site. The AWS should have continuous uptime, enabling builders to mitigate the effects of dust re-suspension due to changing weather conditions.
• Selecting a background site: To calculate the levels of air pollutants at a site compared to an urban baseline, a background site should be selected (Gulia et al., 2020). This should be able to highlight the impact of construction activities on the local AQ.

Assigning more monitors to the site will improve data reliability. However, it might also result in additional overheads and an increase in the quantity of data to be analysed. In that case, given the high dust load at the site, the monitors should be frequently calibrated to ensure accuracy (Feenstra et al. 2019).

Once the AQ monitors have been deployed using one of the monitoring strategies outlined in the previous section, the data collected can be utilised to manage AQ and reduce the sector’s contribution to urban air PM concentrations.

By combining meteorological data with AQ-monitoring data, AQ models can be improved or created to predict pollutant levels, assess the impact of different sources of pollution, and help implement effective pollution control measures. Meteorological data – wind speed and direction, assessments of atmospheric stability, such as temperature inversions, or washing out of pollutants due to precipitation – are particularly useful in predicting the transport of air pollutants. This information can also be used to issue AQ forecasts and warnings, so that site workers or supervisors can reschedule pollutant-emitting activities and take necessary precautions during poor AQ days. Furthermore, the AQ information from the site can be used in two ways: first, by informing the project developer regarding conditions at the site, and, second, by integrating the information into the construction schedule. The data from the AQ monitors could help in assessing the baseline levels of pollutants, analysing trends, showcasing the project’s environmental performance, and demonstrating compliance. This would enable builders to use site specific, data-backed strategies to develop and enforce dust mitigation plans in a timely and efficient way (Figure 3).

There are cases where frontier cities have used air pollutant data as a tool to encourage construction sites to self-regulate. For example, large-scale projects in Wembley Park, London’s low-emission zone, were managed by monitoring on-site AQ (Aeroqual 2017). More than 100 dust monitors have been deployed in the Greater London area, largely to monitor C&D projects. Data from the monitors are sent to the cloud, where they are combined with other information (e.g., on noise and vibrations). The monitors provide data on demand, respond to exceedances, and minimise dust emissions before they have an impact on people or the environment by using live data and warning systems. Similarly, in Saudi Arabia, Freyssinet Saudi Arabia Co. Ltd (FSAC) deployed AQ monitors to protect its workers at one of its construction sites near a high-traffic zone in Riyadh (Construction site monitoring, Oizom 2022). The developers recorded air pollutant information alongside meteorological data to detect sources of pollution, analysed the data using cloud computing software, created historical trend reports, and developed alert modules to notify workers of any potential threat to their health so that appropriate preventive measures can be implemented.

Monitoring building sites is also useful for improving control methods and apportioning the impacts of local and regional sources of pollution. In London, for example, Barts Health National Health Service Trust (London) highlighted their concerns about patient care and health during the demolition of their previous building (IAQM 2022). A monitoring protocol was put in place to provide the requisite proof that the mitigation measures had been successful. The analysis helped in developing a threshold beyond which the work would be stopped and subsequent inquiries were made to develop an alert mechanism.

In another location in London, a monitoring network was established on a larger construction site (London Plan 2016). Vegetated screens were installed to assist in the trapping of PM and provide aesthetic benefits. However, after thorough monitoring and assessment, it was recommended that the site managers consider the targeted application of dust suppression equipment as the screen alone was not enough to prevent resuspension due to the frequent movement of heavy vehicles.

Recently in Paris, monitoring of various government building sites has been introduced to protect employees and residents in the neighbourhood. For example, Parisian authorities demanded that continuous realtime PM monitors be installed at each site throughout the development of The Grand Paris Express, Europe’s greatest metro traversing an urban region (Envirotech 2021). Monitors were placed around the perimeter of each site to estimate the amount of dust particles exiting the site. Each monitor has telemetry and mobile connectivity so that the data can be uploaded onto a cloud monitoring platform and readily accessed and shared with stakeholders. Furthermore, depending on the threshold, a variety of notifications can be generated. For example, the site manager can be notified if the dust concentration level reaches 150 micrograms per cubic metre of air on average over 15 minutes. Such signals will allow site managers to respond quickly and effectively to lower dust levels.