Health determinants inside a health impact assessment

A health impact assessment for a planning application is an exercise in choosing the right determinants and then evidencing them. Get the health impact assessment determinants wrong and you produce forty pages that a committee cannot use. The determinants that matter are the ones your scheme can actually move: housing quality and affordability, air quality, noise, access to green space, active travel, access to food and services, employment, and social connection. Everything else is context.

Councils that ask for one usually ask through a local plan policy or a supplementary planning document, and the trigger is normally a scale threshold or a particular use. Check what the policy says before you scope anything.

Screening whether a full assessment is needed

Screening answers one question: is the scheme likely to have health effects worth assessing in a structured way. Most authorities run a two-stage approach, with a short screening or rapid appraisal for medium schemes and a full assessment reserved for large or sensitive ones.

The things that usually push a scheme into full assessment territory are residential numbers above the local threshold, a hot food takeaway or gambling use near a school, a hospital or care use, a major employment site, or anything that changes access to a facility the surrounding population relies on. In London, the London Plan expects health to be considered and boroughs commonly apply the NHS Healthy Urban Development Unit rapid assessment tool, which gives a consistent set of headings.

Record the screening decision even when the answer is no. An officer who can see that health was considered and screened out is far less likely to ask for the whole thing at week six.

The determinants a planning scheme can influence

A determinant only belongs in the assessment if there is a plausible pathway from something the scheme does to something a person experiences. Write the pathway down as a sentence before you write the section.

The groupings that do real work in a planning application are:

• Housing: dwelling mix, space standards, overheating, daylight, tenure and affordability
• Environment: air quality, noise, odour, light, contaminated land, flood risk
• Movement: walking and cycling routes, public transport access, severance, road danger
• Open space and nature: quantity, quality, distance to the nearest park, play provision
• Local economy: construction and end-use jobs, apprenticeships, local supply chains
• Services and social infrastructure: GP capacity, school places, community facilities
• Safety and cohesion: natural surveillance, lighting, managed public space

Cut anything you cannot evidence. An assessment that claims a scheme improves social cohesion without saying how is worse than one that leaves the heading out.

Baseline health data and its sources

Baseline work is where most assessments go thin. The point is not to reproduce a district health profile but to describe the population who will live with the scheme and the population already there.

Use published sources and name them. Office for National Statistics census and mid-year estimates give age structure, household composition, tenure, car ownership and travel to work. The local authority's joint strategic needs assessment gives the health priorities the council has already committed to, which is the single most useful document because it tells you what the public health team will look for. Government health profile data gives life expectancy, deprivation deciles and prevalence for the ward or middle layer super output area.

Set the geography deliberately. A ward boundary often cuts across the walking catchment of a site, and an assessment that uses the wrong geography invites the comment that the baseline does not describe the people affected. State the geography and the reason for it in one sentence.

Do not manufacture numbers. Where the data does not exist at the scale you need, say so and describe the effect in qualitative terms instead.

Assessing effects on different populations

The assessment has to distinguish between populations, because an effect that is neutral overall can be negative for one group. Older residents, children, disabled people, people on low incomes, people without a car and people with existing respiratory conditions are the groups most often affected differently by a development.

This is also where the assessment connects to the public sector equality duty under section 149 of the Equality Act 2010. The duty falls on the authority, not on you, but an application that has already thought about differential effects makes the officer's job easier. Where the scheme is large enough to need a separate Equalities Impact Assessment, keep the two documents consistent rather than duplicating them.

Be honest about negatives. An assessment that finds no adverse effects at all is not credible, and a committee reading it will assume the rest has been written to a conclusion.

Mitigation and enhancement measures

Every adverse effect needs a response that somebody can be held to. Vague commitments to "promote healthy lifestyles" do nothing. Measures that survive scrutiny are the ones tied to a drawing, a condition or an obligation.

Workable measures include a play area of a stated size and age range, a pedestrian route shown on the layout with lighting levels specified, cycle parking numbers by type, an air quality neutral heating strategy, restricted construction hours, and a local employment commitment in the section 106 agreement. Where the scheme adds green space, the urban greening factor approach used in a Green Infrastructure Plan gives a numeric way of showing what the landscape actually delivers.

Enhancement is not the same as mitigation, and committees notice when the two are blurred. Mitigation reduces a harm your scheme causes. Enhancement adds something the area did not have. Label them separately.

Working with the public health team

The public health consultee sits in the upper tier authority in two-tier areas, which means the district case officer may not know who to ask. Find out early. A short pre-application conversation with public health is worth more than a long report written without one, because it tells you which two or three determinants the team cares about in that borough or district.

Ask three things: which local strategy they want the assessment to respond to, whether they use a particular appraisal tool, and what they expect to see about GP and dental capacity. That last point comes up constantly on residential schemes and is usually answered through the integrated care board rather than the council.

Reporting so a committee can follow it

Committee members read the officer report, not the appendix. Structure the assessment so the officer can lift the findings straight into their report.

A structure that works. Open with a one-page summary table of determinants, effect, population affected and mitigation. Follow it with a short baseline section that states the geography. Then take the determinants one at a time, naming the evidence pathway for each. Close with a schedule of commitments cross-referenced to the drawings and the draft heads of terms, and keep the methodology in an appendix.

An illustrative example. A scheme of 90 flats on a former car showroom sits 400m from a park, on a road inside an air quality management area, in a ward with above-average childhood obesity. The three determinants that carry weight are air quality at the frontage, safe walking routes to the park and school, and play provision on site. The rest of the assessment can be short. The assessment that names those three and evidences them properly beats the one that covers fourteen determinants at a paragraph each.

PlanScope can produce an AI-assisted draft of a Health Impact Assessment structured to these headings, with flags where site data is missing, and councils usually expect a suitably qualified author for this kind of evidence, so professional review is strongly advised. Enter your postcode on PlanScope to see which reports your site is likely to need.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.