If your general liability policy carries the silica exclusion endorsement, its own words take out a claim that dust from your milling, saw-cutting or grinding made someone sick, along with dust damage to other people’s property and the cost of testing and cleaning it up. Whether the endorsement is there is printed on your forms schedule, and nowhere else.
Milling drums, saw blades and grinders: where the dust starts
The dust starts at the cutting edge. NIOSH’s engineering control guidelines for asphalt pavement milling describe the machine plainly: “Cold-milling, which uses a toothed, rotating cutter drum to grind and remove the pavement to be recycled, is primarily used to remove surface deterioration”. The same document says “Dust generated from the cold-milling machines often contains respirable crystalline silica.” and that “This respirable dust can be transported by air currents to worker breathing zones near the milling machine.”
Milling is not the only source on a paving job. NIOSH’s silica and worker health page says “Work activities such as cutting, grinding, polishing, and drilling can generate dust from materials with RCS and then can become airborne.” That covers the saw-cut around a patch and the grinder taking up old striping.
That guidance is written about protecting workers, not neighbors, and it was tested on asphalt: NIOSH says “NIOSH and the Partnership have not evaluated the effectiveness of the best practice dust controls on other non-asphalt road surfaces such as concrete.” A saw-cut through a concrete apron is its own case.
The EPA makes the wider point in its particulate matter basics. Some particles “are emitted directly from a source, such as construction sites, unpaved roads, fields, smokestacks or fires”, and some, “such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye.”
Neighbors, drivers and other trades: who blames the dust on you
A dust claim against your company usually comes from someone who is not on your payroll: tenants whose storefronts and cars are coated, a driver who blames the cloud over the lane for a crash, occupants of a building whose air intake pulled in the dust, and workers employed by the general contractor or another trade on the site.
That last group is easy to miss. To a milling subcontractor, the general contractor’s laborer is not your employee. If that laborer says your dust made him ill, the claim reaches you as a bodily injury claim under your general liability policy, not as a workers compensation question, which is exactly where the silica endorsement does its work.
Regulators describe the same harms. New Mexico’s fugitive dust control rule, which applies to sources in the parts of that state that need a dust mitigation plan, lists “pavement milling” among its construction activities and bars dust that would “pose a threat to public health” or “interfere with public welfare, including animal or plant injury or damage, visibility or the reasonable use of property”. It is one state’s rule for particular areas, and our New Mexico page covers the state’s other requirements.
In Washington, a guide to handling fugitive dust from construction projects, written by a contractors’ association education foundation and hosted on the state transportation department’s site, gives the reasons in a list: “Fugitive Dust can become a nuisance to neighbors by depositing on their property;” and “Fugitive Dust from construction can reduce visibility on roadways and highways, resulting in traffic accidents.” It is guidance, not a department rule; see our Washington page for that state. Neither document speaks to insurance; they explain why people complain.
The base general liability form never says silica
The standard general liability policy does not mention silica or dust anywhere. We read the Commercial General Liability Coverage Form, CG 00 01 04 13, the ISO form as commonly written in the edition we read, and neither word appears in it. A dust claim reaches that form only through its general definitions.
Those definitions let a dust claim in. The insuring agreement at I.1.a reads: “We will pay those sums that the insured becomes legally obligated to pay as damages because of ‘bodily injury’ or ‘property damage’ to which this insurance applies.” At V.3, “‘Bodily injury’ means bodily injury, sickness or disease sustained by a person”, so a lung illness is a bodily injury. At V.13, “‘Occurrence’ means an accident, including continuous or repeated exposure to substantially the same general harmful conditions.” Property damage at V.17.a includes “Physical injury to tangible property, including all resulting loss of use of that property.”
The base form’s pollution exclusion is the other general wording in play. It defines the term broadly: “‘Pollutants’ mean any solid, liquid, gaseous or thermal irritant or contaminant, including smoke, vapor, soot, fumes, acids, alkalis, chemicals and waste.” Dust and silica are not on that list. Whether that exclusion reaches silica dust cut out of an existing pavement depends on the wording and on the law of the state where the claim is brought, and it is not something this article can settle. Our general liability page explains the rest of the base form.
Three sets of trigger words in the silica endorsement
The silica endorsement takes the question out of those general words and answers it with its own. The Silica Or Silica-Related Dust Exclusion is a standard ISO endorsement as commonly written. We read CG 21 96 03 05, a single page whose copyright line names ISO Properties. Check your own forms schedule for the edition you carry.
Under its caution line, “THIS ENDORSEMENT CHANGES THE POLICY. PLEASE READ IT CAREFULLY.”, it adds a new exclusion headed “Silica Or Silica-Related Dust” to the bodily injury and property damage coverage and again to the personal and advertising injury coverage. The verbs differ in each place.
For bodily injury, it excludes “‘Bodily injury’ arising, in whole or in part, out of the actual, alleged, threatened or suspected inhalation of, or ingestion of, ‘silica’ or ‘silica-related dust’.” The triggers are breathing it in or swallowing it.
For property damage, it excludes “‘Property damage’ arising, in whole or in part, out of the actual, alleged, threatened or suspected contact with, exposure to, existence of, or presence of, ‘silica’” and the defined dust. Those fit dust settling on a car or a storefront.
For personal and advertising injury, all six verbs appear together.
Two phrases run through every paragraph. The words “in whole or in part” mean a claim that blames the dust as one cause among several is still within the wording as printed. And “alleged” and “suspected” mean the exclusion is written to reach a claim that says silica was involved, whether or not anyone has tested for it. None of this depends on the “pollutants” definition; it is a separate, named exclusion.
Silica, and anything mixed with it
The endorsement defines both of its terms, and the second is wider than it first looks. “‘Silica’ means silicon dioxide (occurring in crystalline, amorphous and impure forms), silica particles, silica dust or silica compounds.” Then: “‘Silica-related dust’ means a mixture or combination of silica and other dust or particles.”
Set that beside NIOSH’s statement that dust from cold-milling machines “often contains respirable crystalline silica.” The definition is written for mixtures. How a particular claim resolves still turns on its facts, but you should not read the endorsement as limited to pure silica.
When someone else pays for the cleanup and sends you the bill
The endorsement also removes the cost of dealing with the dust, and not only the cost you pay. It excludes “Any loss, cost or expense arising, in whole or in part, out of the abating, testing for, monitoring, cleaning up, removing, containing, treating, detoxifying, neutralizing, remediating or disposing of, or in any way responding to or assessing the effects of, “silica” or “silica-related dust”, by any insured or by any other person or entity.”
That final phrase is the one to notice. A property manager who has an air-handling system cleaned, or a public agency that sweeps a street and invoices you, is some other person or entity. The same paragraph appears under both coverage parts.
Real-World Scenario: A paving contractor mills and overlays the drive lanes of a shopping center on a windy week while the stores stay open. The milling machine’s water sprays clog partway through a shift, and a cloud drifts over a restaurant whose rooftop unit is running. Within the month the landlord sends a bill for duct cleaning and air testing, a server says the dust left her short of breath, and the carpet store next door wants its display floor cleaned. The owner finds the silica exclusion on the general liability forms schedule. Each demand sits against a different paragraph of it, and the owner sends all three to the agent and the insurer the same day, with the crew’s notes on when the sprays failed.
Your own operator’s exposure is a workers compensation question
Dust that reaches your own crew was never a general liability claim, silica endorsement or not. The base form excludes “Any obligation of the insured under a workers’ compensation, disability benefits or unemployment compensation law or any similar law.” and bodily injury to “An “employee” of the insured arising out of and in the course of:” employment. That exposure belongs to your workers compensation and employers liability policy.
OSHA’s respirable crystalline silica standard for construction sets an employer’s duties to its own workers. This article is about everyone else. A later post on how that standard’s table of dust-control methods applies to milling machines will cover the operational side.
Tenders from a general contractor, and the rest of your schedule
Dust claims against a milling subcontractor often arrive through the general contractor or owner, either as a tender under the indemnity clause in your subcontract, which is how indemnity clauses and the insured contract work on a paving job, or as a claim for coverage as an additional insured. The silica endorsement says “This endorsement modifies insurance provided under the following:” and names the whole commercial general liability coverage part, so read it together with the additional insured endorsement rather than apart from it.
The Washington guide makes a point worth carrying into any subcontract: “Fugitive Dust control planning is a partnership between the owner, general contractor, subcontractors and any other party whose activities during the project may lead to the generation of Fugitive Dust.” It adds that “all parties can be held liable for non-compliance and subsequent regulatory actions, including monetary penalties.”
The silica question does not end at the general liability policy. An umbrella carries its own forms schedule, so ask what it says about silica too; how that upper layer is built is explained in umbrella and excess liability for paving contractors. A policy that is limited to the operations you described is a separate question, covered in when a paving policy is limited to the work you declared.
Whether a given dust claim is covered, and whether a contract clause holds up, turns on your policy wording, your contract and your state’s law. This article explains what the forms say; it is not legal advice.
Questions to settle before you bid a milling or saw-cut job
Learn what your program does with a silica claim before the drum touches the pavement. Start with the forms schedule on your general liability policy and on any umbrella. If the silica endorsement is listed, you know the wording above applies. If a differently titled company form is listed, read it the same way. Then ask your agent a narrow question: what does this program do with a dust claim from someone who is not my employee, and which form does that answer come from? Our sealcoating insurance page asks the same kind of question about pollution.
Keep your controls working and on paper. NIOSH recommends that “water-sprays be used to suppress dust on milling machines if ventilation dust controls are not available” and that “Milling machine contractors should implement a water-spray and ventilation control system daily checklist to verify that the dust controls are being operated”. Controls do not change what a policy says, but they reduce the dust that reaches people who might claim, and a dated checklist shows what was running that day.
Read the job’s own dust-control obligations in the contract and any permit before you price the work. The paving contractor insurance overview shows how the rest of your program fits around the general liability policy.
Send us your general liability and umbrella forms schedules, along with the dust-control section of the next milling or saw-cut contract you plan to sign, and request a quote; we will tell you which silica wording you carry and where it sits.