COSHH Essentials: Qualitative Chemical Risk Assessment

Overview

COSHH Essentials (Control of Substances Hazardous to Health) is a qualitative control-banding method developed by the UK Health and Safety Executive (HSE). It is designed to help employers and occupational hygienists identify the appropriate level of control for chemical substances without requiring exposure measurements.

The method assigns substances to one of five hazard groups (A to E) based on their hazard phrases (H or R), and combines this with the quantity handled daily and the volatility (for liquids) or dustiness (for solids) to produce a risk level (1 to 4) with associated recommended control measures.

Hazard groups

Group	Hazard level	Typical H phrases
A	Low	H303, H315, H319, H336
B	Moderate	H302, H312, H332, H371
C	Significant	H301, H311, H314, H317, H331
D	High	H300, H310, H330, H351, H360
E	Very high (CMR)	H334, H340, H341, H350

Any substance with H or R phrases not listed in groups B–E is assigned to group A by default (precautionary principle).

Risk levels and control measures

Risk level	Typical situation	Control approach
1	Low hazard, low quantity/volatility	General ventilation
2	Medium hazard or moderate quantity	Local exhaust ventilation
3	High hazard or large quantity	Containment or closed systems
4	CMR substances or very high hazard	Comply with CMR legislation; detailed assessment

Step-by-step example

1. Classify liquid volatility

For liquid substances, volatility is estimated from the boiling point and the process temperature using the boundary lines defined in the COSHH Essentials guide.

# Toluene: boiling point 111 °C, process temperature 20 °C
coshh_classify_volatility(boiling_point = 111, process_temp = 20)
#> [1] "Medium"

2. Assign the hazard group

# Toluene: H315 (skin irritation), H336 (drowsiness/dizziness)
coshh_grade("H315, H336")
#> [1] "A"

3. Obtain the risk level

coshh_risk(grade = "A", quantity = "Medium", volatility = "Medium")
#> [1] 1

4. Get the recommended control measures

coshh_measures(1)
#> [1] "General ventilation. Low risk."

5. Full assessment in one call

The high-level wrapper coshh_evaluate() chains all four steps:

coshh_evaluate(
  name          = "Toluene",
  phrases       = "H315, H336",
  quantity      = "Medium",
  is_liquid     = TRUE,
  boiling_point = 111,
  process_temp  = 20
)
#>   substance    phrases grade volatility quantity risk
#> 1   Toluene H315, H336     A     Medium   Medium    1
#>                         measures
#> 1 General ventilation. Low risk.

Evaluating multiple substances

coshh_evaluate() is designed to work well with lapply() or purrr::pmap() for batch evaluation:

substances <- list(
  list(name = "Toluene",  phrases = "H315, H336", quantity = "Medium",
       is_liquid = TRUE,  boiling_point = 111, process_temp = 20),
  list(name = "Xylene",   phrases = "H315, H336", quantity = "Large",
       is_liquid = TRUE,  boiling_point = 139, process_temp = 20),
  list(name = "Cement",   phrases = "H315",        quantity = "Large",
       is_liquid = FALSE, dustiness = "High")
)

results <- do.call(rbind, lapply(substances, function(s) {
  do.call(coshh_evaluate, s)
}))

results
#>   substance    phrases grade volatility quantity risk
#> 1   Toluene H315, H336     A     Medium   Medium    1
#> 2    Xylene H315, H336     A     Medium    Large    2
#> 3    Cement       H315     A       High    Large    2
#>                                                                       measures
#> 1                                               General ventilation. Low risk.
#> 2 Specific prevention and protection measures, e.g. local exhaust ventilation.
#> 3 Specific prevention and protection measures, e.g. local exhaust ventilation.

From Excel (no coding required)

For users who prefer not to write R code, expoquimR includes a ready-to-fill Excel template. Download it, fill in one row per substance, and pass the file path to coshh_from_excel():

# Access the built-in template
ruta <- system.file("plantillas", "plantilla_coshh.xlsx", package = "expoquimR")

# Or copy it to your working directory
file.copy(ruta, ".")

# Run the assessment
coshh_from_excel("plantilla_coshh.xlsx")

Language

All output labels are available in English (default) and Spanish:

expoquimr_lang("es")

coshh_evaluate(
  name          = "Tolueno",
  phrases       = "H315, H336",
  quantity      = "Mediana",
  is_liquid     = TRUE,
  boiling_point = 111,
  process_temp  = 20
)
#>   substance    phrases grade volatility quantity risk
#> 1   Tolueno H315, H336     A      Media  Mediana    1
#>                            measures
#> 1 Ventilación general. Riesgo leve.

expoquimr_lang("en")  # reset to English